Why is it that the AR can only be had in only a few calibers?

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I definitely like the 5.56 round, it's an awesome round, it has a good zing to it and at three to five hundred yards doesn't drop too bad, No punch for big game.
I like the 308 round as well, Has a lot of punch and accurate.
6.8 MM I like that cartridge too but...
What about 8MM mauser, 270 Reminton, the classic 30 06 round, the 6.5 Swede?
I know that the magwell would have to conform, Upper, Barrel, buffer and recoil spring, God knows what else. I am pretty sure that there is a demand out there because this AR platform after all is a proven platform and it's not going anywhere. It seems that you could build an AR platform to adapt to these cartridges albeit a slightly longer upper and lower. It is a gas blow back vs rotating lugs I could understand.. If someone makes ARs in these calibers, let me know.
 
Not that I am the most knowledgable on the subject, but I would say because the OS is inadequate for most of the rounds you listed. heheh. Always nice to get in the first stab :evil: .

I would assume production costs would make such firearms astronomically expensive.
 
There are companies that make'em

Dpms makes a 260 Rem, 243 Win, 204 Ruger, 7.62X39, and 300 SAUM. Alexander arms amkes the 6.5 Grendal, which is just as good as the .308 if not better out to 1000 yards. They (alexander arms) also make the .50 Beowulf. Based on the .50AE, it rivals the 45-70. Alexander arms is an amazing company and their stuff is top notch.

Other companies, who I cannot recal at this time, make them in the short magunms.
 
The cost would be high on these rifles if someone were to produce ARs in a long action cartridge like the .30-06, .270, or the other cartridges you mentioned. You already know that the standard AR is in .223 or 5.56 NATO. The magazine well is sized appropriately. 6.8SPC uppers are adaptable to the regular AR lower receiver because the cartridge of the 6.8 and 5.56 are similar in length.

The .308 ARs you see use a different lower receiver. Thus, production costs are higher since the tooling is different.

So if someone were to make a lower receiver that can accomodate the .30-06, production costs would be high and carry over to you. Not to mention actually making an upper receiver with the correct timing for the .30-06. Considering demand for a .30-06 AR is pretty low, it'll probably never happen.
 
The problem with the calibers you mentioned...I believe, is overall length.

The AR is currently available in short action calibers. I'm not sure about the ramifications, if any, of a long action gun with a gas impingement (spelling?) system.

It is easier to make a semi-auto gun if the parts don't have to move as far.
 
Direct impingement with long cartridges shouldn't raise any issues, as long as the gas system is tuned correctly in development.

Witness the AG-42B Ljungman (6.5x55mm) and it's direct, caliber adapted copy, the Hakim (7.92x57mm).
 
Well, you can buy an AR in 30-06, it's just gonna cost you.

I have one.....:evil:

BAR2.jpg
 
The AR15 has a magwell-n-action overall length restriction around 2.3" or so. Those cartridges that can fit into that action, well, have been - 223, 6.8SPC, 6.5 Grendel, 7.62x39, 458 SOCOM, 50 Beowolf, 204 Ruger, and so forth. You can have fast-n-tiny or big-n-slow, but you can't have both; there just isn't enough powder capacity due to the OAL restrictions.

The next step up in cartridge OAL is 2.8" or so - the length of the 'short' full power rifle rounds. The AR10 fits those, and you can find an AR10 in 308, 260, 243, 300 SAUM, and so forth - the variants on the 308 case, if you will. I'm not sure what a 30-06 or 270 will do, tho, that a 308 or 260 won't come awfully close to duplicating. This is probably as big of a semiauto repeater as I'd like to handle for normal hunting use.

Nobody that I know of has tried to make the next step up - supporting chamberings with an overall length of 3.4" (30-06 and its derivatives). There are 50BMG single shot uppers for the AR15 platform, if you really want something fun.
 
They can be made to utilize those cartridges, but the big hurdle is Why? It would be a commercial disaster to spend $$ tooling for 7.5 Swede, and have only you and a few people buy them.
 
I am pretty sure that there is a demand out there because this AR platform after all is a proven platform and it's not going anywhere. It seems that you could build an AR platform to adapt to these cartridges albeit a slightly longer upper and lower. It is a gas blow back vs rotating lugs I could understand.
Click to expand...

There is a company that makes a modular AR low that can allow for adding on new mag wells of different sizes. The idea being the platform can be adapted to more than its current limits. I have seen it in Shotgun News and Guns and Weapons for Law Enforcement.

As for being a proven platform, yes, but in a limited manner as with so many. A platform proven in a given caliber doesn't always seem to transition over to other calibers very readily or without growing pains. For that matter, significant modification to a given platform while remaining in the original caliber can face similar hurdles. Classic examples are 1911s in calibers other than .45 acp, Officer's-sized 1911s, overly short AR15s. Such modifications commonly result in timing issues that can plague the variants.

In the case of the AR15, some adaptations to other calibers involve the addition of parts as adapters and changing out other parts to adapt to the new calibers as well. So aside from timing issues, then is there the problem of additional parts configurations that are not "proven."
 
Quote-"It is a gas blow back vs rotating lugs I could understand.. "

Actually the AR-15 is a rotating lug lock up.
Along with all the other calibers listed above, don't forget .22LR,9mm and .45ACP.
 
Alexander arms amkes the 6.5 Grendal, which is just as good as the .308 if not better out to 1000 yards.
Click to expand...
Uh... :scrutiny:

Let's not go overboard, here. Ignoring logistics and just looking at exterior and terminal ballistics out to 1000 yds, no way. Adding in the logistical considerations will give you have a question of tradeoffs (which is perfectly fine...everything is a trade-off).

Mike
 
The AR platform is extremely versatile. Not because of the cartridges available but because of the modularity of the design. You can swap out stocks and upper receivers easily to reconfigure for anything from close quarters battle or mid/long-range target engagements.

It's very versatile to be able to switch from a 11.5" barrelled upper (assuming it is legal for you) with an Aimpoint sight, to a 16" carbine upper or 18" SPR upper with an Acog, or a 20" barrelled upper with a 10x scope.

While it's not the caliber of choice, you can actually make it to 1000 yards with .223 with the new Sierra 90gr Match Kings. I believe you'll need a 1 in 6.5" twist rate.
 
I think Armalite or maybe DPMS even did a run in 22-250. At least I remember seeing one for sale not too long ago, the seller said it was an extremely limited run item, like 10 or 20 produced.

Justin W.
 
Probably because of one of the main goals of the original design:
-to hopefully have one or two standard ammo size(s) across the board to make logistics easier (makes sense for the military forces to limit the number of different ammo sizes)
 
The AR15 has a magwell-n-action overall length restriction around 2.3" or so. Those cartridges that can fit into that action, well, have been - 223, 6.8SPC, 6.5 Grendel, 7.62x39, 458 SOCOM, 50 Beowolf, 204 Ruger, and so forth. You can have fast-n-tiny or big-n-slow, but you can't have both; there just isn't enough powder capacity due to the OAL restrictions.
Click to expand...

Sure you can have both. Olympic and Dtech sell AR-15 uppers in 25WSSM, and Olympic is coming out with a 30WSSM soon, .308 velocities with 150s. I just might have to jump on that blackrifle bandwagon too. :)


Here's a writeup on that modular magwell lower that gets interesting.
http://www.defensereview.com/modules.php?name=News&file=article&sid=919

I didn't know about that one. Thanks for the tip Double Naught Spy and Rangerruck.
 
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