View Full Version : question on OLL AR build

03-12-2007, 3:17 PM
I have a CMMG 5.56 lower that i'm building with a fixed mag. My question is, will an upper from stag or any other manufacturer have any mating problems, or should I just go with a CMMG upper to match? Also, will a pre-ban upper be legal to use in a fixed mag setup? Any input would be appreciated. Thanks.

Here's what I was looking at:


03-12-2007, 3:28 PM
They should mate up just fine. I have the opposite, a CMMG upper mated to a Stag lower - fits like a glove. These things are all made to the same spec.

03-12-2007, 3:31 PM
You can use any brand upper you want.

I will note that CMMG makes some of the best uppers out there, and their chrome-lined bbls are known to be very accurate.
Yes, you can use a flash-hider equipped upper in a fixed magazine configuration.

I assume this is what you mean by terms 'preban' (and, by extension, 'postban'.) The other items normally associated with the term 'preban' - threaded barrel and bayonet lug - have no relevance to California law, and are just terms of custom now that the Federal law to which these terms actually refer has expired/"sunset".

However, if you want flexibility in going from a fixed-mag w/evil features setup transitioning to a legal gripless build with a MonsterMan or U15 stock, having a barrel without a flash hider makes things more practical: you could have a bare crowned muzzle, a muzzle brake, or a thread protector.

03-12-2007, 3:32 PM
The finish may be a bit different. Last I remember the CMMG had a Teflon like finish. But from your list everything seems to be milspec so you shouldnt have any fit problems. I rarely see the same upper and lowers together. I dont know why that is:confused: it your call.

03-12-2007, 3:33 PM
wow fast replies. thanks guys, i really appreciate it.

03-12-2007, 5:51 PM
Mix-n-match lower/upper assemblies shouldn't be an issue at all. CMMG/Stag are Spec. No worries.

03-12-2007, 6:03 PM
Different upper halves are never a problem to any lower half, if they are made within spec.

Personally, if I were you, I'd get a CMMG upper. CMMG has very complete line of upper halves. There are a lot configurations offered by CMMG and their delivery is not bad.