BioHazard Posted September 8, 2011 Report Share Posted September 8, 2011 Hello, I am by no means new to shooting my father had a sporting goods store for 20 years but sadly he is no longer around to ask questions. I just built my first DPMS LR308, with a 18" barrel rifle length gas system. The thing that drew me to the AR platform is the ability to shoot a variety of calibers but what I was wanting to do is use my lower with a few different uppers. I am going to use the 18" 308 for brush shooting and I have another 24" bull barrel for long range reach out and touch you, and am thinking about getting a 18" 338 just for the heck of it. I have been doing some reading and from what I have gathered the bolt doesn't "HAVE" to be matched to the barrel for moderate accuracy. Does this mean I can just get 2 extra uppers, handguards, gas blocks and tubes and just swap out the bolt and carrier group between uppers?Thanks, I am sure I will have many more questions in the weeks to come. Quote Link to comment Share on other sites More sharing options...
Madhouse Posted September 8, 2011 Report Share Posted September 8, 2011 Welcome aboard BioHazard! Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted September 8, 2011 Report Share Posted September 8, 2011 Yes and no.Not all calibers use the same bolt... But they do use the same carrier. I'm pretty sure the calibers I've seen are 308, 260, 338, 300wsm and 204. Hopefully some of the guys here can impart some wisdom on which use the same bolts. As far as I know they could all be the same or all be different. The charging handle is universal too. Quote Link to comment Share on other sites More sharing options...
washguy Posted September 8, 2011 Report Share Posted September 8, 2011 Welcome aboard !the thing I would do....for each new upper /barrel I would get a new bolt for that particular caliber and use it in the carrier that you already have ...dont see why that shouldnt work <thumbsup> Wash Quote Link to comment Share on other sites More sharing options...
Jgun Posted September 8, 2011 Report Share Posted September 8, 2011 I wouldn't. Even if all of your uppers were chambered to the exact same depth (not likely) and the head space was adequate that you could safely shoot all of your uppers using the same bolt, your not considering the fact that machined parts that mesh (like gears) wear in such a way that they develop a close "fit" where the high spots wear off and the two parts fit together as a matched set. This is why you should mark duplicate parts in an engine when doing repairs and return all parts to their original locations to maintain that fit. It's almost like lapping. Your bolt lugs and barrel extension lugs will also develop that unique "fit" between the two parts. If your life depended on it, you might very well be able to swap BCG's to keep a gun running, but we're talking AR's here not AK's. At the very least I'd suggest that you get a dedicated bolt for each upper. Quote Link to comment Share on other sites More sharing options...
BioHazard Posted September 8, 2011 Author Report Share Posted September 8, 2011 Thanks Jgun, that is what I was thinking just wanted to make sure!Robocop, you said the 204 would also work, I am going to research this a bit because I really want a bull .204 also but was thinking I would need to build a 15 to do this... Quote Link to comment Share on other sites More sharing options...
imschur Posted September 8, 2011 Report Share Posted September 8, 2011 +1Jgun Quote Link to comment Share on other sites More sharing options...
98Z5V Posted September 8, 2011 Report Share Posted September 8, 2011 Be careful with the .338 caliber option - the only .338 you'll be able to shoot from a .308 AR-based rifle will be .338 Federal. No way in hell will you be able to get a .338 Lapua Magnum in it, let alone shoot it. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted September 8, 2011 Report Share Posted September 8, 2011 Here's a list of what you'll be able to shoot through the big-bore AR. This may or may not be all-inclusive - I have no idea how many new calibers, and wildcats, come out everyday....243 Win.260 Rem7mm-08.270 WSM284Win, 35Rem.257Roberts7mmWSM.300WSM.325WSM.338WSM.300 Savage.300 Remington Short Magnum.338 Federal.358 Win.450 Marlin.470 Rhino.500 Phantom Quote Link to comment Share on other sites More sharing options...
Jgun Posted September 8, 2011 Report Share Posted September 8, 2011 I've been hearing about the .338 Ruger compact magnum. I have yet to see the dimensions, but I'm told it will fit a large platform AR. I have not seen an AR in this caliber although I have seen the .338 federal in the AR, and I'm told that when a .308 AR is worn out in the throat. the barrel can be re chambered to .338 federal. Anyone know how the two differ? Is there factory brass available for the Ruger? Quote Link to comment Share on other sites More sharing options...
WCANTERBURY Posted September 9, 2011 Report Share Posted September 9, 2011 Boys, Don't forget that a lot of these magnum rounds are belted cases which may cause feeding problems, and what about the higher gas pressures? Will it fit in the magazine?As far as using a good barrel that has experienced throat erosion and jumping to a larger caliber, maybe. Don't forget about having to bore out the barrel and recut the rifleing. Someone like Krieger may consider reworking one of THEIR barrels, but they may just blow you off for liability reasons.I am looking through my reloading books and I still haven't found the specs on the .338 federal.Sonny <munch> Quote Link to comment Share on other sites More sharing options...
Jgun Posted September 9, 2011 Report Share Posted September 9, 2011 Unless I was misinformed, I was led to understand that the .338 federal shoots the same projectile as the .308, and all that is require is that a .338 federal chamber reamer be run into the old chamber and that the slightly longer length .338 reamer will remove the throat erosion and give you a second life from the barrel. I'm going to see if I can get some kind of definitive confirmation of the accuracy of what I was told. Quote Link to comment Share on other sites More sharing options...
Jgun Posted September 9, 2011 Report Share Posted September 9, 2011 I guess I should have checked this before my first post, I looked on Wikapedia and see that they list the .338 federal as using a .338 bullet in a .308 case. So I guess that your right about the entire barrel having to be opened up .030". Can that actually be done accurately enough to end up with a match quality barrel? Quote Link to comment Share on other sites More sharing options...
WCANTERBURY Posted September 9, 2011 Report Share Posted September 9, 2011 jgun,A 0.338 is usually used for large dangerous animals in North America or long range precision shooting. I would be willing to bet that with a laser centered boring machine this could be done. But, if you have eroded the throat on the barrel, you have also probably introduced stresses in the rest of the barrel. It would make a good practice or hunting barrel, but I don't think it would ever be a match grade barrel like Krieger or Shillen makes from a virgin blank.Once metal becomes heated and cooled it warps like wood, but to a far lesser degree, it becomes hardened and brittle. If it is made with extremely high quality metal with an eye towards reboring the barrel, (Like a commercial diesal engine block.) then I have no doubt that this could be done, especially since you are hopefully removing the surface case hardening in the bore before cutting new rifleing. (My opnion not based in metalurgical study.)Sonny <munch> Quote Link to comment Share on other sites More sharing options...
Jgun Posted September 9, 2011 Report Share Posted September 9, 2011 I originally was told of the feasibility of going to .338 by the owner of ABS when I had them make my carbon fiber wrapped stainless .308 barrel. He told me that if i ever shot out the barrel, he could take it to .338 federal. Of course now that ABS is no longer in business, I'll have to see if anyone else is willing to take that project on should I ever need it. (I've got maybe 100 rds through the barrel so far) but if i ever get around to buying a good optic for it, I will most likely start shooting it more regularly. Thanks for sharing your knowledge. Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted September 9, 2011 Report Share Posted September 9, 2011 Jgun, I'm pretty sure Jense Precision (also known as XPA) now owns ABS. Mike Dagerness (SP?) is their barrel maker/ carbon wrapper. He explained to me the same thing you are describing. Shoot .308 till you get sick of it or you can manage to shoot out his barrel (which he says is about 8k-10k rounds). Then for $150 he will change it over to .338 fed. He guarantees a .5 MOA with his barrels... And even tighter if you let him build the upper.Ps. Ordered my barrel 10 weeks ago... Still waiting. Quote Link to comment Share on other sites More sharing options...
Jgun Posted September 9, 2011 Report Share Posted September 9, 2011 Yeah, Robo, When i heard that ABS was gone, I kind of figured that if I ever got to that place where I actually had shot out the .308 barrel, I'd start by contacting the company that had bought the rights to ABS's wrapping process. Since Mike at ABS assured me that I would be likely to get double the accurate lifespan of a normal stainless barrel, I'm hoping that I won't have to think about doing it for a few years to come. At that point I'll consider the price vs going with a brand new barrel, also, I'll decide at that point if I actually want a .338 federal AR. I'm presently considering different caliber options for my next large platform AR build using the POF receiver set. Since I already have a couple of .308 AR's and I've ordered a .458 SOCOM barrel for my next small platform build, I'm thinking either go for big bore or go for one of the benchrest calibers. I'm not in any hurry, because I've finally come to realize that as soon as I finish one, I immediately start thinking about the next, if not sooner. I don't know what turn around time you were promised, but mine took like 10 months from the time I placed the order, so hopefully yours will be coming soon, and I'm sure it will be worth the wait. Quote Link to comment Share on other sites More sharing options...
WCANTERBURY Posted September 9, 2011 Report Share Posted September 9, 2011 What are the advantages & disadvantages of a carbon wrapped barrel vs. a high quality stainless barrel? Ignorance may be bliss, but not when you are spending hard earned cash!Sonny <munch> Quote Link to comment Share on other sites More sharing options...
Jgun Posted September 9, 2011 Report Share Posted September 9, 2011 Some of us have discussed this on the forum before, so my apologies ahead of time to those of you that are sick of hearing about it. The proponents claim that a carbon wrapped barrel is more rigid and less susceptible to harmonics, along with (depending on which material and process is used) dissipating heat much faster, which is supposed to equate to double the accurate lifespan of a conventional steel barrel. One thing that is not in dispute is that carbon wrapped barrels are much lighter than steel barrels. This can result in a significant weight saving for the complete weapon depending on the barrel caliber, length and contour. Quote Link to comment Share on other sites More sharing options...
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