will a 308 upper fit on a 5.56 lower?

**sheffron23** · April 21st, 2012, 07:57 PM

Wondering if i can just put an 308 loaded upper on my lower and just put an 308 mag in?

**knight0334** · April 21st, 2012, 08:01 PM

No. The .308 cartridge is longer than the mag well on a AR15.

**sheffron23** · April 21st, 2012, 08:18 PM

OK Thanks for the photo to. I figured this but wasn't sure so i figured i ask. Just recently got an carbine and just thinking about all the options i could have for it. Cause if i was going to just get an complete upper i was just going to go for an 308 that way i could have the best of both worlds.

**41800216** · April 22nd, 2012, 12:23 AM

Is there anyone who has made magazines/uppers that would support going the other way? I.e. a 308 lower that could be mated to a 5.56 upper and a 308-sized mag that takes 5.56 rounds (similar to how the M&P15-22 uses 5.56-sized mags for .22 rounds).

**Franchi20/28** · April 22nd, 2012, 04:34 AM

I could swear I just saw something like this somewhere.
An AR10 lower that accepts ar15 uppers.
Give me a day to search around.
Somebody will beat me to it.

**Gun** · April 22nd, 2012, 06:25 AM

http://www.defensereview.com/dr-excl...ry-forces-gif/

**NathanB** · April 22nd, 2012, 09:14 AM

Hers a size comparison between an ar-10 and an ar-15. while the thought is definitley cool I know if i had to grab one rifle to hump around with all day it is not the ar-10. Its heavy. Granted mine is a precision setup but it weighs a ton and is much more cumbersome to handle

**41800216** · April 22nd, 2012, 05:15 PM

Ah the CM901...lol the only reason I know that is because it's in Call of Duty Modern Warfare 3 (maybe other games, but this is one I know). I'm assuming there's no civilian version of this gun though...but that does answer my curiosity!

**fastfive0** · April 22nd, 2012, 08:14 PM

Originally Posted by 41800216

Ah the CM901...lol the only reason I know that is because it's in Call of Duty Modern Warfare 3 (maybe other games, but this is one I know). I'm assuming there's no civilian version of this gun though...but that does answer my curiosity!

Yes colt makes a civi version:

http://www.coltsmfg.com/Catalog/Colt...tLE90116S.aspx

**41800216** · April 22nd, 2012, 11:02 PM

ooooo, thanks for the link, cool to know they exist! At that price though, I'll just have two guns if I really want a 5.56 and .308 capabilities with an AR platform. Yeah they won't be Colt, but I'm not military/contractor/anything remotely close to requiring this kind of ease of AR swap-ability.