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[ARCHIVED THREAD] - 6.8mm SPC FAQ & Load Data Part III (Page 5 of 20)
Your chamber should be the same as the chambers in all the barrels I have made to this point because remington is the source of the drawing for everyone back in 2004. While the JGS drawing has the corrected neck chamfer, my reamer has it the same way as the JGS drawing according to Dave at PTG. So, I have not had complaints about ammo fit in my barrel so there's a good likelyhood that you will not in your barrel either. Remember that the ones doing the complaining are using chrome lined barrels and I seriously doubt you got Chris to make you a chrome lined savage barrel... |
Randall, Your elitist attitude tells me more about yourself than I care to know. If you would have taken a second to think about the post, you would have seen what I was getting at. The idea here is very simple. Your statement about "key element here is RELOADS" are not all rounds loaded in the same manner? It is simple, I have loaded mine to the low side of spec. Yes, my die is down against the shell holder. All my loads work in all my uppers! They are not shorter than normal, they are normal as is indicated by the way that they work in all the uppers. It seems here that people have problems with loading rounds that will function in the uppers that they have. Then people throw blame on the upper or the chamber. Bottom line is that if the industry had a true standard, this crap would stop. But, it seems that manufacturers are not all on the same sheet of music. All the technical data and talk of different chamber sizes are killing this round in this forum. People don't know what to buy or if it has the "correct" chamber size. The bottom line has been in my case, that rounds can be reloaded with out a problem. And most of the uppers that are "tight chambered" are fine and shoot very well. A few articles have been written lately about just one of those "tight" chambered barrels. Don't be so fast to think that you are the all knowing about this round. Take a positive stance and make a difference! |
All specs involve tolerances. The problem seems to be, in general, that various items are 'in spec' because they are within the tolerance band specified. Obviously if items are at opposite ends of various tolerance ranges some 'tolerance stacking' occurs that causes problems - esp combined with an apparent misprint in orig spec diagram as discussed above. Perhaps Ver 2 of the spec will tighten the tolerances so this is avoided?? I really, really, really want a chrome-lined 6.8bbl that can take full-house SSA loads. Bill Wiese San Jose |
WOW, you really didn't realize that I was kidding you with the "special" remark! Your reloads are BETTER than factory ammo because you are NOT having problems. With the die all the way down, it's also likely that they are NOT within spec, but that's probably OK in this case seeing as how the specs are not really within what we consider acceptable working ranges compared to what we expect of other chamberings. All I am saying is that you should consider measuring your reloads to see where they fall compared to specs so you yourself can better understand how much headspace you are running. For everyone else's benefit, headspace is a combination of cartridge dimensions AND chamber dimensions. It's completely acceptable to have a chamber that's out of wack IF your ammo is equally out of wack to accomodate it. The whole reason for standards is so that ammo makers and gun makers have a common point to work from. The absolute headspace dimension is not important as long as the ammo is made to a safe AMOUNT of headspace, say less than 0.007". Of course as we are talaking about a SAAMI cartridge, both the ammo and the chamber SHOULD be within those limits, if only the limits made better sense. I don't understand the elitist remark whatsoever though... |
Tolerance "stacking" of 0.004" as allowed by the SAAMI print is TOTALLY UNACCEPTABLE. This should have been caught MUCH earlier, like at the June 2004 SAAMI meeting when they finally signed off on the drawings... |
Randall, Your "Special" and "McDonald's" comments were not made in a positive way. You made the comment to insinuate that what I was doing was abnormal. In fact, what I am doing is correct. Then you state "Your reloads are BETTER than factory ammo because You are not having problems". I can say "Yes", my handloads are better than any factory loads that I have shot, but have not been able to get any Hornady loads yet. Any person that handloads, knows that they can match a hand load to a rifle and beat factory ammo, it's not "Special", it's a fact. The ammo that I have reloaded does work in all my uppers and that is more than I can say for some factory loads. I have checked my reloads and they are correct spec and understanding headspace is very easy. Your statement "It's completely acceptable to have a chamber that's out of wack IF your ammo is equally out of wack to accommodate it". That makes no sense at all, so you are telling me that "Noveske, CMMG, Model 1 Sales, White Oak Armament and my Hornady dies all have it wrong because my hand loads work fine and I am able to get better performance from hand loads, or do you think that your comment is incorrect? I had a post early in his thread about industry standards, not new info. Die manufacturers understand headspace and provide instructions on how to set them up to maintain the lowest specs so that they will work in any chamber. And, sorry you don't understand the elitist comment. That's because you were to busy with the "Special & McDonald's comments". Now back to the regular scheduled programming! |
Here is the new Noveske 18in barrel. It seems to like a powder charge of 28.7 to 29.0 grains of H322 powder over a 110 grain Hornady V-Max bullet. The point of impact between 28.4 to 29.6 didn't shift more than a half inch. I will work up a optimal charge weight between the 28.7 to 29.0 grains a post some pic's and velocity info after testing. The average groups between these powder charges were; .557, .756, .750, .575, .656. And these were 5 shot groups. The 4th and 5th rounds opened up the groups. I think with the optimal charge weight the rifle will shoot half MOA or mabe slightly under. Here is a pic of the new barrel! 
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Note to RR: Subtle humor is quite hard to carry off over the internet between strangers. I "know" you well enough to know that you were making a funny. Old "chip on the shoulder" hasn't read enough of your posts to get a feel for your personality or else he works for Model 1 Sales  . [ Oops !!!! !!!! Another subtle attempt at humor  ]rj |
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rjay, You could be correct, I don't know him. To a person that doesn't know him, could take the comments in a way that was not intended. I do have a good sense of humor, but don't take bad humor real well. If his intent was good, then I would have no problem to apologize, I just think they were off key. Thanks
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That's cool. I will say that one internet secret I have learned is to always assume the other person is being facetious unless there is NO DOUBT he is insulting me. Now I will let you in on the REAL subtle humor in my previous post. The only really consistent and strongly disparaging remarks I have heard from RR is about the lack of quality of Model One / ER Shaw bbls rj |
I knew this would be read slightly wrong, but I did not have a better way to word it... As a reloader, you need not be as concerned with ABSOLUTE headspace measurements. You do need to be concerned with RELATIVE measurements, as in YOUR ammo compared to YOUR chamber. This is just to say that reloaders have total control over the TOTAL AMOUNT of headspace in their ammo-chamber system. Barrel makers and ammo makers are more CONSTRAINED by industry specs.
No
"Work in any chamber" is NOT the same as "Properly fit in a single chamber" Say your chamber is a the long end of SAAMI specs. Say your dies are at the short end of SAAMI specs. Say you adjust your dies all the way down against the shell holder. You would be sizing the brass MUCH more than as necessary. Does the ammo work in every chamber? Sure. Is it the best situation? No. |
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rjay, I know that some folks have had problems with MDL 1 barrels. I guess that I was lucky, mine shoots very well. I have a few barrels and they perform very well regardless of price. Any time that a company puts out volume, you will have a few bad ones. But, as long as the manufacturer stands behind what they sell, that's the important part. Well...it's time to sneak off from work for some range time.
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Hey, I have Model 1 and Midway's A&B bbls which are ER Shaw so RR is all the time hurting my feelings too  [ oops, another funny ].Have fun making noise, I think I might make it out tomorrow morning. rj |
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Actually Randall is correct in his statements about case sizing and headspace. A lot of dies will make headspace short if screwed all the way down. In fact I can't remember the last time I even did that. I know that is what the instructions enclosed with most dies say but I have really never found the need. I have been reloading for 20 yrs. so I am not a novice. I have reloaded for somewhere in the neighborhood of at least 50 different rifles, shotguns and pistols of various action types without incident. I have also corrected headspace on 1 rifle (an old sporterized Mauser w/about .030" headspace) by necking up 2 calibers and then necking back down creating a shoulder to fit the chamber and fireforming then adjusting the sizing die accordingly. This eliminates case stretch and worries about premature seperation. I have also formed .280 from .30-06 and 7mm WSM from .300 WSM both of which have a headspace difference of about .040". Mind you am an not trying to start a pissing match with you or anyone else and I really don't think that Randall was either. And no I don't know Randall outside of this thread. Randall and Art please continue with your evaluations. It is far better to be informed so customers can ask the right questions when ordering barrel services from whomever. If different reamer manufacturers are using different specs then chambers will differ from the norm or in this case acceptable condition. It is good to know who is using good specs and who may not be. If I pay good money for something I expect good performance from it and not problem after problem. |
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Get this guys, to get my Remmy 700 bolt to even close on my resized brass I have to adjust the die to 3/4-1 turn down PAST just touching the shell holder. I have a Rock Chucker press I'm using. When I put the Hornady sizing die down to just touch the shell holder I was unable to close my bolt on a sized case! WTF was up with that? ETA: that was when I was first sizing the brass. I've left the die set there ever since. Now that I have the die set I've had no problems and my gun groups right about at 1/2 to 3/4 MOA. For 6.8 AR15 CQB work would a CMMG chrome lined "tight chamber" be ok? I know a guy who's selling a 14.5" barrel that I might buy and cut back to 12". I'd throw my SRT can on there and have some fun. Of course all my ammo would likely be hand loads anyway... 
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| When I got my Rockchucker, the set up directions said to lift the ram to the highest position and screw the die until it touched the shell holder. Lower the ram and turn the die 1/4 to 1/2 turn and lock it down there. I've run all my dies like this since I started 7 years ago. I'm only now seeing that there is any other way to set the die up. |
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Adjusting your dies for headspace using the 1/4 to 1/2 turn method works ok most of the time. Certain things like having a die from one manufacture and a shell holder from another can get you into trouble with headspace. Because the manufactures have no standard between them for the machined dimensions of these parts. This is not a plug for Randall but he made me a cartridge headspace gage for the 6.8 and this took the guess work out of die set up for me. Once you set up you sizing die this way you know you are within spec and then can make small adjustment if you like for your rifles chamber. Joe edit for spelling: |
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Press spring is a funny thing. The reason RCBS recommends tightening the die 1/4 to 1/2 turn is because they KNOW that the press is springing. 7/8-14 dies adjust about 0071" per full rotation. That 1/4 to 1/2 turn equates to about 0.018 to 0.036 of preload on the press. Here's an interesting test to try... Set the press at the top of it's travel. On a press that "bumps over", you will need to pull the handle back a little to get into the right place. Now set a die down snug against the shell holder and lock the die adjustment here. Now add a fired case to the shellholder, lubed as usual and size it. With the ram at the top of it's travel, quickly measure the gap between the shellholder and the base of the die with feeler gauges. This is the press spring and it's likely to be 0.010" to 0.020"+ Now, there are other variables in the amount of spring, mainly the brass hardness. Choose a cartridge in which you have several different brands of brass. Run this same test with different brands and you will probably note a difference between the brands... This is because the softer brass sizes easier than the harder brass. The same thing holds true for brass that's been sized a bunch of times vs. new brass. Hopefully, you can see that IF you are going to size without taking all the press spring out, that you need to have consistent brass or the amount of sizing is going to vary. I doubt that they are available for the 6.8, but I use redding's competetion shellholder sets in other calibers. This is a set of shellholders, all for the same caliber, but they are made in different depths. Now, you can setup the headspace a little more consistently, while fully springing the press and still have the ability to adjust exact headspace. It's the best of all worlds.
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Randall: Thats a good point about press spring and brass hardness affecting head space. Probably many who have seen signs of high pressure have been jumping through hoops with different powders and charge weights, headspace, and COAL to try and get velocities that others seem to have no problem getting. I wonder how much the different reamer manufactures work with each other to produce reamers to the same spec, this sure is one chambering they need to address. Joe |
In general, the reamer manufacturers, ammo makers and die makers should NOT need to work together. They are supposed to be able to rely on SAAMI as a source of standardization. In the case of the 6.8, everyone worked from Remington's 2004 drawing. If you read the last 2 pages of this thread, you would see what a quagmire that turned out to be... 
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Followup on my Range Session last week (Page 5). Ok tonight I finally got around to cleaning my rifle. First thing I did was to inspect the chamber. Looking inside I could see a ring of what looked like copper in the chamber (up near the throat). I dipped a chamber mop in some Shooters Choice Bore cleaner then proceeded to mop the chamber with a twisting motion. When I pulled the mop out guess what I found wrapped around it near the end?   (Note the brass in the photo is the one I mentioned that locked up the rifle - you can see/feel where the extractor really pulled on it and where it flowed into the ejector. I crushed the neck to ensure I couldn't reload it.) This came off a bullet (definately copper not brass), though I don't know if it's from the Remmington OTM or SSA TMJ ammo. Anyone think this may be the reason for the sudden signs of overpressure in my rifle? Anyway I continued to clean the rifle. Bolt was dirty but there were no brass shavings under the extractor, and the ejector worked smoothly. I did note the bore cleaner pulled what I considered a lot of copper from the bore. Though I normally don't use bore cleaner (just CLP). Rifle is now clean and hopefully I'll get a chance to fire her thursday evening and get her re-zeroed (especially as I have a LaRue mount now). Here is a picture I took tonight - I promise I'll take better photos as time allows. 
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Forest To be honest with you I think it is our FMJ. You more than likely have the combat loads and it is building up pressure in your weapon. Check the OAL of the cartridge, seat the projectile down to 2.185 this will increase the free bore and may drop your pressures or to be on the safe side Just return the rounds to us and we will replace them for you. We have rework several chambers that was not chromed lined and what a difference in preformance. The X-Treme needs the additional free bore, the SMK, Pro-Hunters and Barnes Triple Shock are not effected. Art - SSA |
No doubt that a ring of bullet metal left in the chamber would cause a sudden pressure problem. |
Could this...
and this...
explain this?
Caused by a chamber that has the "wrong" throat angle... suggesting that the bullet obturation was significant enough to shear that portion of the base off. Can't remember what chamber Forest has. Just a thought... |
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So do we have any new info on who has 'correct' chrome-lined AR barrels chambered in 6.8SPC that work with full-house (i.e., SSA 'combat' loads)? - We know that CMMGs are too tight for this. - We know E.R. Shaws can be problematic (Model1, etc). - Stag's 6.8 bbls are Shaws, so unless something changed I'm staying away from that. - Barrett seems to wanna sell a whole, pricey upper. Anyone have more info on upcoming chrome-lined barrels? Gotta be able to safely run loads like SSA 'combat' loads. Bill Wiese San Jose |
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Just got off the horn with Stag Arms about their new 6.8SPC bbls, chrome-lined. The guy said they have tested with 'hot' loads, were aware of SSA situation, apparently appropriate changes were made, and they have no problems with any ammo brand in testing. However, they're only selling 6.8 complete rifles now. Uppers may start being sold toward end of August or so. I urged them to do some longer barrels as well (I'd like a chromed 18" 6.8 SPR bbl). I also urged them to let folks on AR15.COM know about their chromed 6.8 bbls working with all ammo. Bill Wiese San Jose |
It's NOT the throat angle, it's the neck chamfer angle that we were speaking about. See the drawings on the last couple pages for details. It turns out that even though the drawings are wrong, the actual reamer IS correct in Forest's case. The other difference over time is that the throat LENGTH spec has been extended to make the extreme bullet work reliably. What Art was talking about is that the extended throat gives the bullet more support before it obturates. With the shorter throat, the bullet obturates 0.040" prematurely. In my opinion (I can't say this without pointing fingers, sorry Art) this is a bullet problem because all the other bullets do not have this same premature obturation issue with similar 0.060" long throats. Keep in mind that the Extreme bullets are made with copper plated on to a lead core where most other bullets are conventional drawn jacket with a core swaged into them. The copper plating is not as strong as a conventional jacket, hence the obturation issue. |
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Randall You are correct with regards to the X-treme. When we got started with the 6.8 the only game in town was Barrett for us and their weapons. Actually we did not develop the X-Treme we adopted it because at the time that is what the Military was using. Than we hit the market thinking everyone was on the same page as Barrett -wrong. We have made changes to the X-Treme a while back but the system has to get burged (dealers etc). I will tell you this no matter what projectile you use the longer throat helps reduce pressures and you can get better velocities with no ill effects to accuracy. We are trying hard to keep the X-Treme because it is a low cost projectile and the Military still likes it. Art-SSA |
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On a related thought (to the adjusting the cartridge length idea) Would it be safe to pull the XTreme projectile with a kinetic bullet puller, then pour the powder back into the case and seat a Remington 115gr FMJ in the case. I figure I could measure the length of the Extreme bullet & an unmolested cartridge and determine how much of the base was in the case - then seat the FMJ so the case capacity was the same. So the only variables that would change would be the bullets profile (the FMJ has a sharper shape) and possible the neck tension. I have 98 or so FMJs waiting to be loaded anyway, and if this would work it would same me a trip to UPS. Is this crazy talk or a viable idea? (I don't know as I'm new to reloading) |
This is crazy talk. If you do it, you will want to be back behind one of these:  Each load is worked up according to the bullet's bore resistance, length etc... You can't just match case capacity by seating a DIFFERENT bullet to a similar capacity and expect to be safe! |
<Doh!> Glad I asked, I hadn't considered different friction in the bore! Thanks. |
You can buy a collet bullet puller and the correct collect for less than $20 from Midway. I bought a Forster because that was the cheapest [ at the time ] when you factored in the cost of the collet. With the collet style puller you run the cartridge up, tighten the collet via the appropriate handle, lower the ram and voila, bullet gone a missing. Move the case to your loading block, loosen the collet handle and catch the bullet as it falls out. In my experience there is no significant damage to the bullet so it is totally reusable. I could be wrong but I am under the impression that all the first generation of SSA 6.8 loads used the same powder charge, just different bullet styles. Using this as my guide I loaded up several different bullets on top of the original SSA charge. I had no serious pressure signs. I will cruise over to Midway later and get you a link for the puller. I didn't see any on sale in the current flyer. rj |
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Art Did you get any official feedback from CMMG? I saw this over in the equipment exchange...
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Very interesting comments on this thread for a guy who just wants to buy a 6.8 upper that shoots the good stuff. I was just starting to figure out the mid-length and gas pistion vs di and now I have to worry about if my gun will blow my face off. I still want one.
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We sent CMMG samples of all our rounds and John with CMMG had said all is well and that they did not have any problems, even with the Barnes Triple Shock at 2,715 FPS. These cartridges are at the very bottom of the dimensional spec as CMMG at least was running tight chambers. We have been running our cartridges to the low end for a while now to insure it functions in all weapons. Art-SSA |
Forest If you can save the XTreme projectile drop the powder charge to 28.5 and you are good to go. Only when the pressure reach 49,000 problems arise in some guns. At 28.5 you will have pressures at 46,500 well below the 49K. Art-SSA |
Sean You should be able to run all our loads thru your LW. If are going to use the X-Treme buy it for now directly from us, they will be the improved version. As for the SMK and Pro-Hunters there is no issure with them. You will get over 2,600 FPS (16 inch barrel) and at 100 yards get one hole with the SMK. Go to Midways website and read the comments, with 5 stars being their top rating all reveiws were 5's. Art-SSA |
Art, What type of bullet is the 110 gr. triple shock used in your 2,815 FPS load? Controlled expansion? Also, is that the only bullet that would work with that load? I have to say Art, getting those kind of figures consistently is quite an innovation. Congratulations. Justin |
Thanks Art. Hopefully, I'll be ordering soon. Thanks again. Sean |
[ARCHIVED THREAD] - 6.8mm SPC FAQ & Load Data Part III (Page 5 of 20)
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