AR question, about caliber.

[Brute Killer]

If an AR lower says multi caliber, and the rifle is chambered in 5.56, will that lower accept and run a 308 upper?

[Colton]

No

[Bruiser]

Nope. AR-10's are not milspec. So even between manufacturers they won't necessairly fit, much less 5.56.

[JustinJ]

No. .308 is an AR10, bigger than an AR15

[chrisk]

No but there are several alternatives to the 5.56 when it comes uppers.

[mikerosa]

As far as I know, the AR-10 is whole different ball game. I own 2 two 15’s and a 10. The 10 is a different animal. I’m sure it can be made to handle other rounds, but I’d assume something close in size.


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[Tye]

And remember, in the big frame ARs, there is LR308 and AR10. Those parts don’t mix from what I recall. Also, the LR308 Upper can come in high or low. There is a lot more to the big guns compared to the AR 15

[trophy8]

Nope. AR-10's are not milspec. So even between manufacturers they won't necessairly fit, much less 5.56.

Mil spec has nothing to do with it. Large frame vs small frame. And there’s 2+ types of large frame gas guns.

[Artos]

If an AR lower says multi caliber, and the rifle is chambered in 5.56, will that lower accept and run a 308 upper?

Try to think of it more along the lines of what calibers will fit in the traditional AR-15 with the .223 / 5.56 magazine focusing more on the OAL.

The AR-15 eats all sorts of shorty rounds all the way up to the 458 Socom & 50 Beaowulf but those rounds are so big, they sit single stack in the same size mag size.

.308 OAL rounds work around an entire different family. Personally, I feel the AR-10 platform is too heavy and bulky.

[Bruiser]

Mil spec has nothing to do with it. Large frame vs small frame. And there’s 2+ types of large frame gas guns.

when u=it comes to manufacturesrs it does which was the point i was making thank you very much

[trophy8]

when u=it comes to manufacturesrs it does which was the point i was making thank you very much

What parts won’t work on a standard AR15 platform if they aren’t mil spec with exception of buffer tube/ stock?

[Brute Killer]

Roger.

[geezer56]

I have several AR's in oddball calibers. 6x45, 25-45, 30 American, 7.63x39, and grendel to name a few. The 7.62x39 is the best bang for the buck.

[Bruiser]

What parts won’t work on a standard AR15 platform if they aren’t mil spec with exception of buffer tube/ stock?

jez u have no idea what u are talking about

[Javelin]

jez u have no idea what u are talking about

not to get in the middle but I think bruiser is talking ar10s and trophy is talking ar15. in ar15 trophy is correct. in ar10 platforms there is no mil spec to my knowledge.

however I think bruiser got the OP wrong as his answer didnt really apply to the question.

the simple answer to the OP is no ar10 platforms for large calibers like 308 are larger than the smaller ar15 platform of 556