AR Sponsor
BCA bolt action upper for $350? (Page 6 of 21)
|
Received my builders kit today. Was missing the bolt handle, the screws that hold it onto the carrier, and the ass-plug or whatever it is that goes in the back end of the receiver. A couple of calls later and they said they will be sending me the missing parts.... Bear Creek is kinda LOL I think, or maybe not, I dont know... |
|
Originally Posted By Burnsome-: Received my builders kit today. Was missing the bolt handle, the screws that hold it onto the carrier, and the ass-plug or whatever it is that goes in the back end of the receiver. A couple of calls later and they said they will be sending me the missing parts.... Bear Creek is kinda LOL I think, or maybe not, I dont know... Holy crap. I was interested at first but after this plus all the work to make things halfway smooth, hard pass. I thought BCA might have turned a corner on QC. I guess not. 
|
Join the N.R.A.
Beware speaking with a sharp tongue as you are apt to cut your own throat.
My name is John Wick, you killed my puppy, prepare to die.
Beware speaking with a sharp tongue as you are apt to cut your own throat.
My name is John Wick, you killed my puppy, prepare to die.
|
Originally Posted By Burnsome-:[/b] Originally Posted By Burnsome-:[/b] Received my builders kit today. Was missing the bolt handle, the screws that hold it onto the carrier, and the ass-plug or whatever it is that goes in the back end of the receiver. A couple of calls later and they said they will be sending me the missing parts.... Bear Creek is kinda LOL I think, or maybe not, I dont know... 
|
|
It turns out the upper is thicker, width-wise, than a normal one. I got a Stag Arms slimline handguard for this build.Turns out the wings on the sides of the handguard, presumably for anti-rotation purposes, are flush with the upper instead of going around it like they would on a regular upper. Good thing I got this handguard for cheap, because it's going to get those wings taken off with a bench grinder! 
|
|
Originally Posted By Moondog: I wish I hadn't re-visited this thread. I'm having my taxes done Friday and I've been thinking of ideas on how to spend any refund money. A receiver kit looks tempting. I have a 20" HBAR with a FF tube I can cannibalize for parts. if you like tinkering this will be a fun one to mess with. i like where this thread is headed. guys trying to figure out how to smooth the action, little tweaks for better operation, etc. |
Joined:
May 2023
Posts:
311
EE: 0% (0)
WI, USA
|
Originally Posted By Big-Bore: Holy crap. I was interested at first but after this plus all the work to make things halfway smooth, hard pass. I thought BCA might have turned a corner on QC. I guess not. Originally Posted By Big-Bore: Originally Posted By Burnsome-: Received my builders kit today. Was missing the bolt handle, the screws that hold it onto the carrier, and the ass-plug or whatever it is that goes in the back end of the receiver. A couple of calls later and they said they will be sending me the missing parts.... Bear Creek is kinda LOL I think, or maybe not, I dont know... Holy crap. I was interested at first but after this plus all the work to make things halfway smooth, hard pass. I thought BCA might have turned a corner on QC. I guess not. RE: Missing parts -- that's a total f-up on their part. Not the first company that's whiffed on something like that. Someone screwed up in their packing dept. But, I suppose you get the labor you pay for, and the products are priced accordingly. Frustrating as it is, it is a kinda funny, obvious, and easy-to-fix fuck-up. RE: smooth running I understand your reluctance, and hopefully BCA will make a few dimensional and production tweaks to eliminate or reduce some of these issues. Lord knows there'll be a gen 2 at some point, or maybe just a tweak in their current package. Who knows. It's not hard to get it running half-way smooth, and with a good bolt+barrel combo, I found it pretty easy. Most of what I've worked on was to see how much smoothness, silence, and performance I could squeak out of the platform. Admittedly, I am trying to push the limits, not just have good operation. For example, I didn't even know about the bolt-lug/extension catching issue because it wasn't one for me with the Tromix bolt. So, presuming you avoid that fiasco by using a quality bolt, it's not that much work. The thing I did have to do to get it running decently -- we'll call this "half smoothly",  .1) The port door edges being sharp on the inside took 5-10 minutes to deal with once identified as the issue. For me this was necessary. At this point, I had full, reliable functionality. Some bumps in cycling, but no hard "catches" to stop things. Some wear appearing at rear of top edge of the cutout for the charging handle. But reliably operational. Beyond that, my efforts to maximize smoothness, quietness, and reduce wear beyond what I expected. To those ends (for those that don't want to scroll back a page), I tuned other parts: 0) Trued the receiver. I'd do that for all my receivers. Monitoring the truing process, I saw BCA's face wasn't far off true to any major degree. This could probably be skipped. 1) Polished the carrier. This took mere minutes, and the smoothness greatly increased. My thought was that this carrier has a much, much larger bearing area than a semi-auto bolt, and since force of friction is proportional to the surface area, the bearing surface friction was likely much greater than a semi-auto. I figured there was a lot of improvement to be gained here. 2) Reshaped rear of key to smooth out a contact point with the side of the gas key raceway that is contacted during retraction. This never stopped or really interrupted cycling, it just added texture: a little bump that now feels like even less. Polish for same reasoning as 1. 3) Cam pin. First, this can be solved with getting a quality rounded head cam pin instead of modding the existing one. Drop in part, no work. Front port side corner caused impact wear, but very minimal. Rear corners can impact sides of gas key raceway on retraction while coming into alignment. This change lengthens life as much as smoothing things out. 4) Charging handle smooth/polish becomes unnecessary if washers are added to screws that are larger than the handle base and become the surfaces that contact the receiver instead of the steel charging handle. 5) Carrier bottom + hammer face polishing. This added a lot of improvement to smoothness, but not as much as 1. 6) Added nylon washers to bolt handle screws. These provide a deadblow effect for the carrier on retraction, on chambering, and on locking the chamber shut. They also provide forward and rearward force which holds the handle in pace. While I did cut the wings off, it's only necessary if you don't want to remove your buffer, or if you have a folding or bufferless lower. I have mine on a bufferless lower. That wasn't about improving so much as compatibility. I wanna make clear, that 1-6 above are me trying to maximize performance to try and achieve what I'd expect from a carrier/receiver priced much higher than this. They are hardly necessary to make it run smoothly, but they take the operation up a notch. At the end of my tuning, my bolt moving back and forth feels like plates of sliding glass with copious lube between them. The only metal-on-metal impacts now are the bolt's face and lugs making contact with the barrel & barrel extension and the rounds being stripped from the magazine. RE: update on those charging handle screws+washers Here's what I've settled on for now -- known, easily bought item -- for screws/washers securing the handle: 1) Thick nylon washer: 11/64" ID, 3/8" OD, 1/8" thick. (Trim down OD to 0.335" - 0.350". Adjust OD for desired performance, locking force. White was what was available.) 2) 10-32 rounded button head screw slightly longer than original handle screw to account for thicker washer. Screw head diameter may need to be reduced to fit base. (I know only one is this type in the picture.) 500+ action cyclings with the above and almost no visible wear. The firmness of the nylon improves the securing of the charging handle when locked forward. Instead of an internal spring providing all the force holding it shut, the nylon washers press forward and backward at the same time, wedging it in with friction on smooth but slightly compressible surfaces. Other than perhaps swapping out for black nylon washers at some point, I like how this is working.   
|
Joined:
May 2023
Posts:
312
EE: 0% (0)
WI, USA
|
Originally Posted By VTD: A little update on my bracket thingy. I took a couple of days and sort of learned how to use freecad so I could provide accurate dimensions and drawings to Paladin and see if he can help make a metal version. I moved the bolt handle back another half inch. https://www.ar15.com/media/mediaFiles/26478/freecad_jpg-3488667.JPG https://www.ar15.com/media/mediaFiles/26478/IMG_0353_JPEG-3488669.JPGhttps://www.ar15.com/media/mediaFiles/26478/IMG_0354_JPEG-3488671.JPG Originally Posted By VTD: A little update on my bracket thingy. I took a couple of days and sort of learned how to use freecad so I could provide accurate dimensions and drawings to Paladin and see if he can help make a metal version. I moved the bolt handle back another half inch. https://www.ar15.com/media/mediaFiles/26478/freecad_jpg-3488667.JPG https://www.ar15.com/media/mediaFiles/26478/IMG_0353_JPEG-3488669.JPGhttps://www.ar15.com/media/mediaFiles/26478/IMG_0354_JPEG-3488671.JPG Nice diagrams. Looks like you picked up enough skills to communicate effectively with a machinist. Say, if you move the bolt handle back another half inch as you say you plan on, how about also putting a second mounting spot for the handle further forward, too? Customizable handle position. Originally Posted By Slyce: whose gonna be the first to add these uppers to a FM ranch rifle or Fightlite SCR lower to make the ultimate "i shoulda just bought classical bolt action" ?? https://i.postimg.cc/Dyq9zhBQ/LW-Thermal-BA-fixed.jpg Thought I put a picture up of my upper on my FM Ranch lower already, but I must not have. That was my destination from the get-go, so yup, someone went there pretty quick.  I've been tempted to post a picture of my A-bolt .270 , one of my Remington 870 12gas, an M4 clone, and this with the appropriate math symbols between them. ETA: GUN MATH!  This also gives a good illustration of why VTD's extension for the charging handle position change makes sense, given bolt platform ergonomics. |
|
Originally Posted By PreacherOfGadget: RE: Missing parts -- that's a total f-up on their part. Not the first company that's whiffed on something like that. Someone screwed up in their packing dept. But, I suppose you get the labor you pay for, and the products are priced accordingly. Frustrating as it is, it is a kinda funny, obvious, and easy-to-fix fuck-up. RE: smooth running I understand your reluctance, and hopefully BCA will make a few dimensional and production tweaks to eliminate or reduce some of these issues. Lord knows there'll be a gen 2 at some point, or maybe just a tweak in their current package. Who knows. It's not hard to get it running half-way smooth, and with a good bolt+barrel combo, I found it pretty easy. Most of what I've worked on was to see how much smoothness, silence, and performance I could squeak out of the platform. Admittedly, I am trying to push the limits, not just have good operation. For example, I didn't even know about the bolt-lug/extension catching issue because it wasn't one for me with the Tromix bolt. So, presuming you avoid that fiasco by using a quality bolt, it's not that much work. The thing I did have to do to get it running decently -- we'll call this "half smoothly", .1) The port door edges being sharp on the inside took 5-10 minutes to deal with once identified as the issue. For me this was necessary. At this point, I had full, reliable functionality. Some bumps in cycling, but no hard "catches" to stop things. Some wear appearing at rear of top edge of the cutout for the charging handle. But reliably operational. Beyond that, my efforts to maximize smoothness, quietness, and reduce wear beyond what I expected. To those ends (for those that don't want to scroll back a page), I tuned other parts: 0) Trued the receiver. I'd do that for all my receivers. Monitoring the truing process, I saw BCA's face wasn't far off true to any major degree. This could probably be skipped. 1) Polished the carrier. This took mere minutes, and the smoothness greatly increased. My thought was that this carrier has a much, much larger bearing area than a semi-auto bolt, and since force of friction is proportional to the surface area, the bearing surface friction was likely much greater than a semi-auto. I figured there was a lot of improvement to be gained here. 2) Reshaped rear of key to smooth out a contact point with the side of the gas key raceway that is contacted during retraction. This never stopped or really interrupted cycling, it just added texture: a little bump that now feels like even less. Polish for same reasoning as 1. 3) Cam pin. First, this can be solved with getting a quality rounded head cam pin instead of modding the existing one. Drop in part, no work. Front port side corner caused impact wear, but very minimal. Rear corners can impact sides of gas key raceway on retraction while coming into alignment. This change lengthens life as much as smoothing things out. 4) Charging handle smooth/polish becomes unnecessary if washers are added to screws that are larger than the handle base and become the surfaces that contact the receiver instead of the steel charging handle. 5) Carrier bottom + hammer face polishing. This added a lot of improvement to smoothness, but not as much as 1. 6) Added nylon washers to bolt handle screws. These provide a deadblow effect for the carrier on retraction, on chambering, and on locking the chamber shut. They also provide forward and rearward force which holds the handle in pace. While I did cut the wings off, it's only necessary if you don't want to remove your buffer, or if you have a folding or bufferless lower. I have mine on a bufferless lower. That wasn't about improving so much as compatibility. I wanna make clear, that 1-6 above are me trying to maximize performance to try and achieve what I'd expect from a carrier/receiver priced much higher than this. They are hardly necessary to make it run smoothly, but they take the operation up a notch. At the end of my tuning, my bolt moving back and forth feels like plates of sliding glass with copious lube between them. The only metal-on-metal impacts now are the bolt's face and lugs making contact with the barrel & barrel extension and the rounds being stripped from the magazine. RE: update on those charging handle screws+washers Here's what I've settled on for now -- known, easily bought item -- for screws/washers securing the handle: 1) Thick nylon washer: 11/64" ID, 3/8" OD, 1/8" thick. (Trim down OD to 0.335" - 0.350". Adjust OD for desired performance, locking force. White was what was available.) 2) 10-32 rounded button head screw slightly longer than original handle screw to account for thicker washer. Screw head diameter may need to be reduced to fit base. (I know only one is this type in the picture.) 500+ action cyclings with the above and almost no visible wear. The firmness of the nylon improves the securing of the charging handle when locked forward. Instead of an internal spring providing all the force holding it shut, the nylon washers press forward and backward at the same time, wedging it in with friction on smooth but slightly compressible surfaces. Other than perhaps swapping out for black nylon washers at some point, I like how this is working. https://i.imgur.com/bUfBnx5.jpeg https://i.imgur.com/pjubK0q.jpeg https://i.imgur.com/3n3Y1j2.jpeg Originally Posted By PreacherOfGadget: Originally Posted By Big-Bore: Originally Posted By Burnsome-: Received my builders kit today. Was missing the bolt handle, the screws that hold it onto the carrier, and the ass-plug or whatever it is that goes in the back end of the receiver. A couple of calls later and they said they will be sending me the missing parts.... Bear Creek is kinda LOL I think, or maybe not, I dont know... Holy crap. I was interested at first but after this plus all the work to make things halfway smooth, hard pass. I thought BCA might have turned a corner on QC. I guess not. RE: Missing parts -- that's a total f-up on their part. Not the first company that's whiffed on something like that. Someone screwed up in their packing dept. But, I suppose you get the labor you pay for, and the products are priced accordingly. Frustrating as it is, it is a kinda funny, obvious, and easy-to-fix fuck-up. RE: smooth running I understand your reluctance, and hopefully BCA will make a few dimensional and production tweaks to eliminate or reduce some of these issues. Lord knows there'll be a gen 2 at some point, or maybe just a tweak in their current package. Who knows. It's not hard to get it running half-way smooth, and with a good bolt+barrel combo, I found it pretty easy. Most of what I've worked on was to see how much smoothness, silence, and performance I could squeak out of the platform. Admittedly, I am trying to push the limits, not just have good operation. For example, I didn't even know about the bolt-lug/extension catching issue because it wasn't one for me with the Tromix bolt. So, presuming you avoid that fiasco by using a quality bolt, it's not that much work. The thing I did have to do to get it running decently -- we'll call this "half smoothly", .1) The port door edges being sharp on the inside took 5-10 minutes to deal with once identified as the issue. For me this was necessary. At this point, I had full, reliable functionality. Some bumps in cycling, but no hard "catches" to stop things. Some wear appearing at rear of top edge of the cutout for the charging handle. But reliably operational. Beyond that, my efforts to maximize smoothness, quietness, and reduce wear beyond what I expected. To those ends (for those that don't want to scroll back a page), I tuned other parts: 0) Trued the receiver. I'd do that for all my receivers. Monitoring the truing process, I saw BCA's face wasn't far off true to any major degree. This could probably be skipped. 1) Polished the carrier. This took mere minutes, and the smoothness greatly increased. My thought was that this carrier has a much, much larger bearing area than a semi-auto bolt, and since force of friction is proportional to the surface area, the bearing surface friction was likely much greater than a semi-auto. I figured there was a lot of improvement to be gained here. 2) Reshaped rear of key to smooth out a contact point with the side of the gas key raceway that is contacted during retraction. This never stopped or really interrupted cycling, it just added texture: a little bump that now feels like even less. Polish for same reasoning as 1. 3) Cam pin. First, this can be solved with getting a quality rounded head cam pin instead of modding the existing one. Drop in part, no work. Front port side corner caused impact wear, but very minimal. Rear corners can impact sides of gas key raceway on retraction while coming into alignment. This change lengthens life as much as smoothing things out. 4) Charging handle smooth/polish becomes unnecessary if washers are added to screws that are larger than the handle base and become the surfaces that contact the receiver instead of the steel charging handle. 5) Carrier bottom + hammer face polishing. This added a lot of improvement to smoothness, but not as much as 1. 6) Added nylon washers to bolt handle screws. These provide a deadblow effect for the carrier on retraction, on chambering, and on locking the chamber shut. They also provide forward and rearward force which holds the handle in pace. While I did cut the wings off, it's only necessary if you don't want to remove your buffer, or if you have a folding or bufferless lower. I have mine on a bufferless lower. That wasn't about improving so much as compatibility. I wanna make clear, that 1-6 above are me trying to maximize performance to try and achieve what I'd expect from a carrier/receiver priced much higher than this. They are hardly necessary to make it run smoothly, but they take the operation up a notch. At the end of my tuning, my bolt moving back and forth feels like plates of sliding glass with copious lube between them. The only metal-on-metal impacts now are the bolt's face and lugs making contact with the barrel & barrel extension and the rounds being stripped from the magazine. RE: update on those charging handle screws+washers Here's what I've settled on for now -- known, easily bought item -- for screws/washers securing the handle: 1) Thick nylon washer: 11/64" ID, 3/8" OD, 1/8" thick. (Trim down OD to 0.335" - 0.350". Adjust OD for desired performance, locking force. White was what was available.) 2) 10-32 rounded button head screw slightly longer than original handle screw to account for thicker washer. Screw head diameter may need to be reduced to fit base. (I know only one is this type in the picture.) 500+ action cyclings with the above and almost no visible wear. The firmness of the nylon improves the securing of the charging handle when locked forward. Instead of an internal spring providing all the force holding it shut, the nylon washers press forward and backward at the same time, wedging it in with friction on smooth but slightly compressible surfaces. Other than perhaps swapping out for black nylon washers at some point, I like how this is working. https://i.imgur.com/bUfBnx5.jpeg https://i.imgur.com/pjubK0q.jpeg https://i.imgur.com/3n3Y1j2.jpeg Used your steps (except for the nylon washers at this time) and it has made things so much smoother! Probably 20-30 minutes of elbow grease to do it. Just wanted to say thanks for the diligent work up on this. |
Joined:
May 2023
Posts:
315
EE: 0% (0)
WI, USA
|
You are quite welcome. I'm glad it's useful, and I'm having fun experimenting. ETA: I just had the dumbest idea regarding recoil reducing these self-contained bolt uppers. Kynshot makes a recoil reduction system for shotguns intended to be used with conversions that allow use of an AR carbine buffer tube stock + pistol grip on a shotgun. The device screws in where the buffer tube would, and provides the outside interface of the buffer tube for a stock to attach. Internally it provides some sort of spring cushioning (and possibly more?). I'd bet that system could work with this, when the bolt wings are removed. Combine a recoil reduction system meant for a shotgun with a nice padded buttstock, and I could see .450 BM, .458 SOCOM, .50 Beowulf, & friends all being pretty darned soft on the shoulder. |
|
Originally Posted By Dan375: There are probably tons of counter points but why not just get a standard side charger, remove the gas tube and block the gas port with the gas block. Then you'd have a "Fast Action" rifle that accomplishes the same thing? |
|
Originally Posted By Dan375: There are probably tons of counter points but why not just get a standard side charger, remove the gas tube and block the gas port with the gas block. Then you'd have a "Fast Action" rifle that accomplishes the same thing? I even bought a lev-ar to help cycle so I don't have to mortar. |
Shoot straight and tell the truth!
Joined:
May 2023
Posts:
317
EE: 0% (0)
WI, USA
|
Originally Posted By Dan375: There are probably tons of counter points but why not just get a standard side charger, remove the gas tube and block the gas port with the gas block. Then you'd have a "Fast Action" rifle that accomplishes the same thing? A straight pull bolt AR, as you describe, is either not properly secured shut when the bolt is closed, OR it has extra forces that will fight cartridge extraction. A straight pull bolt action is mechanically at a great disadvantage when extracting cartridges compared to a proper bolt upper like BCA's. For some of those cartridges that like to stick when extracting *ahem* .458 SOCOM *ahem*, it makes extraction MUCH easier. A straight pull bolt requires some sort of tension to keep it closed -- the buffer system. That buffer system then applies force against the back of the carrier, making extraction unnecessarily difficult. This upper eliminates that buffer spring force during extraction, even if the buffer system is installed, by virtue of a shortened carrier. This system also allows removing the entire buffer system while still locking the bolt closed -- weight savings. In a standard straight-pull bolt, if the tension of the spring system is removed, then the bolt is never actually locked, and just one firm bump away from sliding out of battery. ETA: Quiet. This action, as I've tuned mine, is much quieter chambering a round than I have been able to get any of the 3 straight-pull bolt uppers I've built (.300 BLK, .350 Legend, and 6.5 Grendel). There are times this could be important. ETA 2: Laws. (not my reason) Not everyone lives in the US, and even here there's places with more restrictive gun laws, like it or not. |
|
Originally Posted By Dan375: There are probably tons of counter points but why not just get a standard side charger, remove the gas tube and block the gas port with the gas block. Then you'd have a "Fast Action" rifle that accomplishes the same thing? I built a 300Blk exactly how you’re describing. And as Preacher said, extraction becomes difficult, resulting in having to mortar to extract. I “slicked up” mine as Preacher detailed, and no issues when extraction and is quite smooth. Just an FYI from someone who has done e what you mentioned and now this…this is soooo much better |
Joined:
Dec 2023
Posts:
1189
EE: 100% (7)
USA
Joined:
May 2023
Posts:
318
EE: 0% (0)
WI, USA
|
Originally Posted By Slyce: welp BCA said they’d ship me out the gas journal shutoff collar, but i received 2 split washers for the bolt handle lol. so if anyone was missing those and receives a gas block lmk  I swear BCA is the business equivalent of the hyper intelligent alcoholic at the urinal next to you who, while enthusiastically rambling in drunk speech about some break-thru idea, finally turns full on toward you, urinating on both your pants, feet and all over the floor. It'd just be nice to have the great idea without getting our feet pissed on for the privilege. They can't get out of their own way. ETA: RE: another "why?" Given BCA's price point, if a bolt action is desired, then why not? At $187 for the billet upper receiver + bolt-action BCG combo, it's competitively priced compared to semi-auto BCG + receiver sets. With other more expensive approaches, there was always the cost as a big "why not?". With this receiver, the price is right, too. |
|
Originally Posted By Burnsome-: Received my builders kit today. Was missing the bolt handle, the screws that hold it onto the carrier, and the ass-plug or whatever it is that goes in the back end of the receiver. A couple of calls later and they said they will be sending me the missing parts.... Bear Creek is kinda LOL I think, or maybe not, I dont know... Received my missing parts today. Unfortunately they sent me the kit for the side-charging upper and not the bolt action upper so my parts are still officially missing Round 3 coming up Monday I guess |
|
Word to the wise, if you're gonna cut off the wings from the back end of the bolt carrier, don't cut it all the way near the main body, leave yourself 3/4" or so. I cut near to the body of the bolt carrier and now it's a little janky when pushing the bolt back forward and locking it into battery. Without the wings on the back side, the carrier will tilt out a little to the right and the back end will catch on the right side of the receiver. I'm going to "fix" it by using a file to smooth out the area on the receiver it's hanging up on. Good thing I went into this knowing it was going to be a dremel special and not trying for any points for a beauty contest! |
| I cut my wings off right at the main body, but then I took a file and beveled the outside edges for fear of it doing that. When beveling, I have had zero hangups or any resistance. Just an FYI. But of course, after Filing the bevel edge, I used 2000 grit wet sandpaper with oil on it to give it a mirror like polish |
|
My BCA upper arrived Wednesday, and a PSA 300BO upper minus the BCG arrive yesterday (it was cheaper than buying a barrel and Midwest Ind handguard separately, plus I now have a spare M4 upper too). The PSA/Midwest hex rail matched the profile of the BCA upper almost perfectly. The anti-rotation tabs fit with no problems. Initially cycling the bolt was difficult, but once I did the recommended rounding of the cam pin, it's pretty good now. Now I'm just waiting for a scope and Triggertech trigger to arrive. |
Joined:
May 2023
Posts:
321
EE: 0% (0)
WI, USA
|
My recommendation when cutting down the wings is to maintain the entire "full diameter" area, as all of that constitutes a "bearing surface" for cycling. If you cut the wings off just past where the carrier diameter shrinks down, upon full retraction, the carrier rear will be just shy of the rear of the upper receiver. I think I understand most aspects of what the designers were trying to accomplish with their carrier design, but I feel the compatibility with bufferless lowers alone is enough reason shorten the wings. I'm curious how the conversation went during design to arrive at that length. I'm also curious why they didn't maintain the full carrier diameter further rearward. |
Joined:
May 2023
Posts:
324
EE: 0% (0)
WI, USA
|
Nylon washers: for silence, smoothed cycling, solving bolt-lug catching malfunctions, reducing ejection port wear, and increasing bolt-closed lock force Parts list: 2x - nylon washer (11/64" ID, 3/8" OD, 1/8" thick) 2x - button cap hex drive screws (stainless steel, 10-32, 1/2" long) All parts to be modified. I chose stainless because I like the style and there's no rust concern with ground edges. If well oiled, standard black oxide coated screws should still be fine. I also thought the stainless made the white nylon washers stand out less. If my local hardware store had these in black nylon, I would have used that instead of white. In a semi-auto, nylon would get soft pretty fast, but here it should be fine, even with a fairly rapid shooting schedule. Nylon is flexible, and tightening the screws down on the washers will cause them to swell outwards, allowing some adjustment. However, before any deforming occurs they can be tightened down firmly enough that the charging handle is still held firmly in place. Step 1: Screw screw through nylon washer It's gonna be a tight fit, so you'll probably need to use pliers or a vise to hold the washer. At this point, marring isn't a concern, but once the washer is shaped, it is. A different screw can be used for shaping the washers than for installation -- a longer one makes this part easier.  Step 2: Secure threaded end of screw into drill or drill press. Start the motor!  Step 3: Shape the washer Using a rough (80-120 grit) sandpaper, reduce the diameter of the washer, leaving it slightly wider in the center. Use 320 grit to finish. My washer's final diameters are ~0.33" rear washer, ~0.35" front washer. Step 4: Shape screw heads in a similar manner: OD 0.34". Step 5: Grind/file screw tips until length is 0.45" I misplaced one of my washers, if you wonder why one appears different. I don't recommend losing parts.  Step 6: Install And here's them in my new build, and updated pictures now that I got a bipod on it. DO NOT STORE CLOSED & LOCKED. Nylon under pressure will deform over time. Keep a spare set on hand, too. This is experimental, eh?   All I really need to add is a swivel sling stud now. And strip, repair, and refinish the stock. Ah, projects that beget projects. eta: some more notes |
|
Originally Posted By PreacherOfGadget:. I'm also curious why they didn't maintain the full carrier diameter further rearward. perhaps they reduced it to eliminate that possibility. |
| Preacher…I went to Ace Hardware and picked up stock # 35089B (000 Beveled Washers, black in color) from the plumbing section along with 2 more 10/32 screws that were a bit longer than factory. Chucked them in my drill press, filed/sanded them down to 5/16 OD. Not sure of life span of cycles, but it sure reduced the action cycling sound. |
Joined:
May 2023
Posts:
326
EE: 0% (0)
WI, USA
|
Delrin is known generically as acetal copolymer, and I ordered 1/2" rods on Amazon for $12: Delrin Rods |
Joined:
May 2023
Posts:
328
EE: 0% (0)
WI, USA
|
Originally Posted By Hijo202: Preacher…I went to Ace Hardware and picked up stock # 35089B (000 Beveled Washers, black in color) from the plumbing section along with 2 more 10/32 screws that were a bit longer than factory. Chucked them in my drill press, filed/sanded them down to 5/16 OD. Not sure of life span of cycles, but it sure reduced the action cycling sound. If you're looking for the quietest, this is probably that option. Using a hard rubber like those, if I looked up the part right, they can last a while, but will be more susceptible to damage from tight pinching. I ended up finally causing damage while giving mine the "torture test" approach. But the sound reduction is better than nylon, and probably the best in my experimentation. I think my mystery washer was similar to one of these, but in a flat configuration. It was in a small part drawer with, among other rubber washer types, ones like the part you mentioned. Given even the slightest amount of care, this might be the best option... HOWEVER -- be careful using rubber on both the back and front screws. The softer washer material on both front and back could allowing charging handle tilt if pulling hard enough. I can't wait to see hear how time and use test these options we're trying. ETA: I'm sure an appropriate sized softer aluminum would also be appropriate for this part to reduce wear and improve cycling, though probably would not be as quiet as any of the other materials we're working with here. |
|
I think I'm going to wait awhile and see if BCA makes any changes/ enhancements to the design. This thread has loads of great modding information, however I'm not much of a tinkerer. Also waiting a bit will allow me to decide which caliber I should choose. A 350 Legend bolt upper would be cool. |
|
Originally Posted By Moondog: I think I'm going to wait awhile and see if BCA makes any changes/ enhancements to the design. This thread has loads of great modding information, however I'm not much of a tinkerer. Also waiting a bit will allow me to decide which caliber I should choose. A 350 Legend bolt upper would be cool. For what it's worth, I bought a complete 350 Legend upper and swapped out the barrel to 300 Blk and a different handguard and I've had zero issues running the upper without any mods. I did removed the bolt catch from my lower and left the buffer and buffer spring in to dampen the rear ward movement of the bolt but that's a matter of personal preference. |
|
Originally Posted By Burnsome-: Anyone tried the POF roller cam pin on their setup yet? Burnsome…I have not yet. However, for sh”@‘s and giggles, I took the factory cam pin, and went to town on the grinder. It is more of an oval shape now with the corners really lowered and rounded. Figured I had nothing to loose before buying another part. It has worked without any issue at all. So, at this time, I’m gonna stay with that until a little gremlin rears its ugly head (hopefully not) |
Joined:
May 2023
Posts:
336
EE: 0% (0)
WI, USA
|
Originally Posted By Moondog: I think I'm going to wait awhile and see if BCA makes any changes/ enhancements to the design. This thread has loads of great modding information, however I'm not much of a tinkerer. Also waiting a bit will allow me to decide which caliber I should choose. A 350 Legend bolt upper would be cool. Originally Posted By Moondog: I think I'm going to wait awhile and see if BCA makes any changes/ enhancements to the design. This thread has loads of great modding information, however I'm not much of a tinkerer. Also waiting a bit will allow me to decide which caliber I should choose. A 350 Legend bolt upper would be cool. Originally Posted By ninja99: For what it's worth, I bought a complete 350 Legend upper and swapped out the barrel to 300 Blk and a different handguard and I've had zero issues running the upper without any mods. I did removed the bolt catch from my lower and left the buffer and buffer spring in to dampen the rear ward movement of the bolt but that's a matter of personal preference. That's the thing with BCA -- inconsistency because one of the places they save a lot of money is taking it easy on fine finishing details and Quality Control. Their business model is high volume sales at low costs, backed by above average (but not perfect) customer service that seems pretty generous. It seems generous because they often approve repair/replacement, but the bottom line is it's cheaper to replace a handful of defectives if they meet some easily and quickly determined criteria than it is to do extensive quality control on every part and assembly. For example, a severely over-torqued barrel nut can cause an alignment issue between the bolt and barrel, leading to issues with cycling. Parts could all be good, but assembly can be less than ideal. Issues induced in assembly can't all be addressed with design changes. Even after a revision, you still might hit this issue occasionally with a BCA complete upper. A good chunk of the work I did is to make carrier & receiver combo that costs under $200 run as close as I can manage to something that costs over $400. (Second number is kinda arbitrary.) Originally Posted By Burnsome-: Anyone tried the POF roller cam pin on their setup yet? I haven't tried POF roller cam. I tried a Foxtrot Mike gen II rounded cam pin (from their bufferless uppers). I have several of those uppers, and tried one of those cam pins. Turns out it's wider than a standard cam pin. I wouldn't have guessed. So, avoid that one. I also pulled a Lantac CP-R360 domed-head rounded cam pin from my enhanced Lantac BCG, and that works wonderfully in the BCA bolt-action carrier. However, it costs about $10 more than the POF roller cam as an individual part. ETA: I'm happy with, and still using the original cam pin after rounding the corners. |
|
I have a safety concern with these. I hope someone can tell me why my concern is wrong. I received a stripped BCA bolt upper and started putting it together today. Everything went together great. It cycles pretty nicely as it is. My safety concern is that is is pretty easy to have the bolt lugs partially engaged with the bolt fully forward. It will dry fire in this condition. If it were to be fired with the lugs only partially (50%?) engaged wouldn't the strength of the lugs and containment of pressure be compromised? When the bolt handle is locked fully forward and down, the bolt lugs are fully engaged. But I can easily imagine the bolt handle getting a small bump and it ending up in the partially engaged position. It sits there just fine. What do you all think? I have not contacted BCA to ask about this yet.  
|
| Here is the issue you need to figure out. If an AR-15 bolt is not fully locked, the hammer will still fall but it will not strike the firing pin. Therefore, it is almost impossible to have an actual out of battery discharge. So the question is, does the BCA modified carrier prevent the hammer from striking the firing pin if the bolt is not completely locked up as it is with the AR-15? A quick test is to simply load up a case with primer only, no powder or bullet, then half lock the bolt and drop the hammer. If the primer fires, that's a problem. But if it goes click as the hammer falls, as it should, but it does not strike the firing pin and set off the primer, then all is well. That's a simple test but be sure to wear safety glasses anyway. |
Join the N.R.A.
Beware speaking with a sharp tongue as you are apt to cut your own throat.
My name is John Wick, you killed my puppy, prepare to die.
Beware speaking with a sharp tongue as you are apt to cut your own throat.
My name is John Wick, you killed my puppy, prepare to die.
Joined:
May 2023
Posts:
338
EE: 0% (0)
WI, USA
|
I see your point. Couldn't it also then be fired while the charging handle is simply held in a forward position, too? Hold it forward with right hand, pull trigger with left (or a branch or whatever catches it. Very good point. And likely a fundamental imperfection in the design, given that by its nature, the hammer must travel a full path falling when the carrier is "locked", and travel the same path resetting when it is "unlocked". I'd be curious to see what BCA says. If someone who reloads has one of these, I'd say see what happens with unloaded brass with just a primer when you drop the hammer in a "half-locked" and "unlocked, manually held closed" conditions. That'll answer things right quick. ETA: re: Big-bore , the way the carrier is cut and moves, I think the hammer will fall locked or unlocked, if it's fully forward. |
|
Originally Posted By Big-Bore: Here is the issue you need to figure out. If an AR-15 bolt is not fully locked, the hammer will still fall but it will not strike the firing pin. Therefore, it is almost impossible to have an actual out of battery discharge. So the question is, does the BCA modified carrier prevent the hammer from striking the firing pin if the bolt is not completely locked up as it is with the AR-15? A quick test is to simply load up a case with primer only, no powder or bullet, then half lock the bolt and drop the hammer. If the primer fires, that's a problem. But if it goes click as the hammer falls, as it should, but it does not strike the firing pin and set off the primer, then all is well. That's a simple test but be sure to wear safety glasses anyway. Can confirm it will fire with the bolt held closed and not rotated and with the bolt not completely down.Attached File |
|
If the bolt is even slightly open the firing pin will not hit. If the bolt handle gets bumped the bolt will move out of battery making it so the pin cannot hit the hammer. That's the whole reason for the bolt spring I assume. ETA: I wonder what Uintah does to prevent firing until the lugs are engaged? |
Joined:
May 2023
Posts:
339
EE: 0% (0)
WI, USA
|
My first thought is the carrier's geometry below the firing pin is the place the address this. A solution would be leaving on more material on the left side (open position) so the hammer can't fall completely. But to rotate back to that from closed, the additional material would need to be angled so the hammer wouldn't catch on it, but instead would be pushed backward slightly when the carrier rotates. It looks like they made no attempt at something like this. (I can also see some issues arising here, including compatibility issues based on hammer width, and issues with forces to the hammer being applied in a direction never intended, among others.) The cut in the carrier is as if the vertical opening were cut once, the bolt rotated, then the cut made again. I'm glad someone noticed the issue. Wonder what BCA's response will be. |
|
Originally Posted By VTD: I tried exactly this just now. Can confirm it will fire with the bolt held closed and not rotated and with the bolt not completely down.https://www.ar15.com/media/mediaFiles/26478/IMG_0395_jpeg-3494757.JPG HARD PASS! I think if I want a bolt gun I’ll stick with my Remington/Winchester/Ruger/Weatherby/Mauser… and leave the BCA to braver souls. Thank you for verifying that this thing can fire out of battery. |
Join the N.R.A.
Beware speaking with a sharp tongue as you are apt to cut your own throat.
My name is John Wick, you killed my puppy, prepare to die.
Beware speaking with a sharp tongue as you are apt to cut your own throat.
My name is John Wick, you killed my puppy, prepare to die.
Joined:
May 2023
Posts:
340
EE: 0% (0)
WI, USA
|
I gotta say my thoughts of doing additional builds on this just came to a halt. I'm not upset I got one, did some work on it, etc. but safety is safety. I dropped BCA an inquiry. I'm now curious if they were aware of this aspect of their design and OK'd it for sale, or if nobody noticed the issue. I'm also curious how they choose to answer said inquiry. Double that statement above on the curiosity about Uintah precision. I feel the fundamental design flaw is that the carrier rotates to lock the bolt. Ideally the bolt would lock while the carrier is moving forward, and the carrier turning locks the carrier in place. After a night of thinking, I feel like this should have been addressed with an alternate cam path and receiver geometry. There's no good way I can contemplated to retroactively make this safe. |
BCA bolt action upper for $350? (Page 6 of 21)
AR Sponsor