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Posted: 11/26/2013 8:09:27 PM EDT
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New to this forum, and this design of rifle. I would like to pick some brains about the things that kept me away from the AR design.
I have resisted until recently buying an AR (LR-308), I always figured to build one from scratch in my overly equipped home machine shop. My question to all those with many more years in the know: Is there any reason the buffer tube is on the lower? Do you really have to tear down and clean them that much more than a Garand or a bolt gun when used for general hunting and target shooting? Could an upper and lower be just as effective for these purposes built in the form of a stick with a lower that pins on below? It would in the bolt gun world be the equivalent of blueprinting, truly aligning the buffer tube with the receiver bore. Coming from the traditional muzzle loading, bolt gun, and falling block world, it seems that there could be some improvements that the bench rest folks have done, applied to the AR design. Also being of old school and having several 30-06, 270, and 25-06 around would one not just as well stretch the action a little further and chamber for cartridges that I already have in the family. I am a bit stubborn and thought that the .223 was a nice cartridge in the Contender pistol, but not so much in a rifle, where I prefer the 22-250. For that matter, why is the 22-250 not a top pick in AR chamberings? I did not find any answers to these questions after searching, I may have missed them though, and they may be questions put to bed years ago. I have a bit of a rind, so let the flogging commence! |
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What is it that you really want to do and for what purpose? About the buffer......just keep it cleaned with routine maintenance and that is enough.
The beauty of the AR15 and AR10 platforms are to build a great lower so that you can build multiple uppers for different applications. Options are endless! |
| Thanks for the welcome. I mostly like to tinker and build. I had no experience with AR's until a non mechanically inclined friend built one this spring. I had considered trying to build one, but knew nothing about them, even though I grew up shooting and building muzzle loaders since near 35 years ago. I had been away from shooting much for many years, but my boys are getting old enough to learn, well actually older than I was when I started shooting centerfires. My youngest shot a better group with my newly acquired LR-308 than my wife that used to qualify with them. This may become a sickness, the only medicine may be more! Time will tell. |
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Quoted:
Is there any reason the buffer tube is on the lower? Where would you expect it to be? Do you really have to tear down and clean them that much more than a Garand or a bolt gun when used for general hunting and target shooting? WTF, no. Could an upper and lower be just as effective for these purposes built in the form of a stick with a lower that pins on below? It would in the bolt gun world be the equivalent of blueprinting, truly aligning the buffer tube with the receiver bore. Why would that matter in the least. Coming from the traditional muzzle loading, bolt gun, and falling block world, it seems that there could be some improvements that the bench rest folks have done, applied to the AR design. Also being of old school and having several 30-06, 270, and 25-06 around would one not just as well stretch the action a little further It's rather involved and expensive to reengineer a semi auto rifle and all the moving parts to a new action length. Lucky for you Cobb already made you an AR type rifle in 30-06 action length, the MCR300. Unlucky for you, the demand was low, and the product was dropped in the Cerberus/Freedom Group reorganization. Maybe you'll get lucky and find one for sale. and chamber for cartridges that I already have in the family. I am a bit stubborn and thought that the .223 was a nice cartridge in the Contender pistol, but not so much in a rifle, where I prefer the 22-250. For that matter, why is the 22-250 not a top pick in AR chamberings? It won't fit in a 223 size action, and is a bit short for a 308 size action... and 243 kicks its behind on performance and barrel life? I did not find any answers to these questions after searching, I may have missed them though, and they may be questions put to bed years ago. I have a bit of a rind, so let the flogging commence! |
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Cobb made one you say, never heard of them, but they must not have been in the shooting sports that I previously enjoyed. Thanks, I will research that one.
I am not looking for production, only a one off or two for personal use. My wife likes the platform, I have not run a magazine full through one yet. Just never had much interest in them. Growing up in the 80's the AR was still regarded by my dads age group as a pray and spray unit. They were not held in high regard for accuracy like a bolt action. I have since noted the number of them winning Camp Perry and other well known matches, that indicated that they could be much better than I previously thought. There in lies the beginnings of interest, the "they are all ugly" was disproven by Doug Turnbull with his TAR-10, WOOD and Color Case Hardening, things of beauty! I have the equipment, background and experience to make most of the pieces, the Bolt I would purchase (heat treating would eat up the cost savings), Springs, while they are not difficult to manufacture, are time consuming, and just not cost effective, FCG is pretty difficult, not impossible to machine and readily available therefore another expected purchase, Barrels are very difficult to produce in a manual machine shop, and quality would not be consistent with even a low grade manufacturer with the specialized equipment, Upper, Lower, Bolt Carrier and all other hard parts can be made easily, they would be the special design parts anyway. With the buffer as an integral part of the bolt carrier there would be a much longer, more stable bearing length to consistently make the bolt face perpendicular to the chamber, it may not make any accuracy difference, but appears to be the next step in accuracy that has not been widely tried. Just asking questions about them, and learning, from every post at this point. Keep the responses coming, that is how we all learn. Thanks. |
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Quoted:
With the buffer as an integral part of the bolt carrier there would be a much longer, more stable bearing length to consistently make the bolt face perpendicular to the chamber, it may not make any accuracy difference, but appears to be the next step in accuracy that has not been widely tried. It's pretty much irrelevant to accuracy. ARs are not bolt rifles. The bolt itself locks up into the barrel/barrel extension, and the BC and everything behind it "floats" a little bit. People tried to make "national match" bolt carriers with a tight fit to minimize movement but it was found that they often hurt accuracy by not "floating" so therefore not allowing the bolt itself to align itself correctly. If there's a place for "blueprinting" on an AR15 type rifle, it's the front edge of the upper receiver that the flange on the barrel tightens up against... some take the time to true that surface up, although some brands/models of upper receivers are known for a near perfect fit on that surface right from the factory. There are a couple of good books out there on competition AR rifle building, I don't own one but have read parts of one. An AR type rifle is just different than bolt rifles and trying to apply bolt rifle accurizing techniques directly to an AR are often futile if not counterproductive. One thought on your desire for a .22-250, there are a couple wildcats of the 6.8spc necked down to 22 that might be pretty similar in performance, and 6.8 size bolts and magazines are readily available. |
Welcome. The unified in-line upper receiver with recoil system is actually where the AR10 evolved from.
I do know of some smiths who have built AR15's using the blue print approach, to include: * Using the bore as the reference datum, profiled a high-end barrel concentric to the bore * Cut the breech-end threads true to the bore, concentric to the bore * Trued the threads of the barrel extension * Trued the face of the barrel extension * De-edged and polished the barrel extension feed ramps * Trued the face of the upper receiver to the raceway * Blended the barrel extension feed ramps and upper receiver ramps * Trued the bolt face * Lapped the lugs to the barrel extension teeth This was on a 6.5 Grendel, and his first test load was under a 1/2" at 100yds at Lee Kay range back in 2009. He had done an AR10-sized action as well. One company at least has done a .22-250 in the AR15 by machining out the rear of the magazine well to give them more COL, but the cut through the mag well wall, and it doesn't look very professional. As to the cases based off of the x57 Mauser, you can meet .30-06 performance with shorter, fatter cases. I practically never clean the inside of the extension tube, unless submersion has occurred. I also Cerakote all metal parts, except for the inside of the bore, the extension, the Bolt Carrier Group, and other internal parts. Receivers, barrel exterior, handguard, and extension tube all get Cerakoted. Glen Zediker's book is good on accuracy tips for the AR15. The Competitive AR15 Builders Guide: How to Choose and Assemble All the Components to Construct Your Ultimate AR-15 by Zediker, Gled D. |
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Thanks, that is the kind of things I am looking to find out.
I was a little disturbed in the research I have done, every Tom, Dick and Harry (making videos) seems to think you just slip a steel barrel extension into an aluminum receiver and it will shoot well all the time, (even hot). I do believe that an interference fit at that point, and as you said faced exactly perpendicular to the upper receiver bore would be major points in accuracy. In a lathe you would work from that end to ensure that is trued as required. I assume many are actually done in a mill, due to the fixture and ability to perform many other operations in one fixture. I should look into some books on the subject, I really never considered buying an AR until the last couple years as most of my friends now have them. Really planned on multiple occasions to buy a CMP Garand, even had the paperwork filled out more than once and never sent it off. Was always torn between the M1 and an M1A, but the LR-308 fills the bill, even though it lacks wood! The wildcats built on 6.8 SPC just might be something to look at, 22-250 is readily available, but I rarely buy any unless I am restocking my brass supply, so that would be an option, my 700 Rem is needing rebarreled anyway. |
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Quoted:
Thanks, that is the kind of things I am looking to find out. I was a little disturbed in the research I have done, every Tom, Dick and Harry (making videos) seems to think you just slip a steel barrel extension into an aluminum receiver and it will shoot well all the time, (even hot). I do believe that an interference fit at that point, and as you said faced exactly perpendicular to the upper receiver bore would be major points in accuracy. In a lathe you would work from that end to ensure that is trued as required. I assume many are actually done in a mill, due to the fixture and ability to perform many other operations in one fixture. I should look into some books on the subject, I really never considered buying an AR until the last couple years as most of my friends now have them. Really planned on multiple occasions to buy a CMP Garand, even had the paperwork filled out more than once and never sent it off. Was always torn between the M1 and an M1A, but the LR-308 fills the bill, even though it lacks wood! The wildcats built on 6.8 SPC just might be something to look at, 22-250 is readily available, but I rarely buy any unless I am restocking my brass supply, so that would be an option, my 700 Rem is needing rebarreled anyway. 
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Oh, that is a lot like what I was thinking! I guess it started there and evolved! So I am not so far out there in my thoughts after all. Thanks.
The trueing and blueprinting of the locking lugs and the bolt face as with the bolt extension makes absolute sense. Order of operations in the machining will make or break any accuracy, as well as reordering the operations can make quantity or manufacturing time. While I mentioned the 30-06, the 25-06 has really captured my heart. I have a Ruger No. 1 in 25-06 and pretty much quit carrying anything else for many years. |
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