Would you trust a complete upper and lower slapped together?

[AndyLate]

What do you think the they do all day at BCM?

That was my thought when I read complete BCM upper and lower. A complete factory BCM may *may* have a better fit between the upper and lower than your gun does, but functionally there is nothing to worry about.

I effectively built an LMT SPM14 with a lightly used complete LMT upper and a complete LMT Defender lower. Saved a pretty penny doing it and ended up with a gun I can be rightfully proud of https://lmtdefense.com/firearms/spm14

The only thing you and I cannot do is honestly sell them as complete factory guns.

Andy

[RHINOWSO]

The only thing you and I cannot do is honestly sell them as complete factory guns.

Andy

But lets be honest, who here really has a 'complete factory gun' after owning an AR for more than a week?

New stocks, triggers, sights, buffer system, BCG, muzzle device, safety, rails, etc, etc, etc.

[Pappabear]

You should be good to go. But run it hard and clean it before it goes to your bedside. The hard part for me is to clean it.

PB

[Uni-Vibe]

But lets be honest, who here really has a 'complete factory gun' after owning an AR for more than a week?

New stocks, triggers, sights, buffer system, BCG, muzzle device, safety, rails, etc, etc, etc.

I do. My 1999 Bushmaster M16A2-forgery is box stock after all this time.

And my 6920 that I bought months ago is box-stock, except I pulled off the Magpul BUIS rear sight and put on a carry handle.

So there are a few of us Cavemen.

[MWAG19919]

Use what helps you sleep soundly. That said, I have about 3,800 rounds through my BCM, which is really a complete BCM upper on a complete BCM blem lower. I added a Geissele trigger and an A5 buffer, but not because of any reliability reasons. The rifle has been flawless.

Just buy quality whatever you do.

[mark5pt56]

I do. My 1999 Bushmaster M16A2-forgery is box stock after all this time.

And my 6920 that I bought months ago is box-stock, except I pulled off the Magpul BUIS rear sight and put on a carry handle.

So there are a few of us Cavemen.

I think he was making a funny. You know a brand new Colt, etc won't "run" if you don't put the whizbang parts on it, it is said here. Oh, I meant "slap" them on or better yet, "throw" them together.

[thegreyman]

The AR 15 by design is modular. You can slap an upper and lower together at home or you can have the factory lovingly, gently attach them.

[ViniVidivici]

The AR 15 by design is modular. You can slap an upper and lower together at home or you can have the factory lovingly, gently attach them.

As a good friend of mine said, "the Lego set for adults".

[Doc Safari]

I have had one and only one incident where an upper wasn't completely functional with a lower.

I had two identical Colts in the 1990's and decided to swap uppers because I wanted the "nicer looking" components together for a safe queen and the "minor blemmed" upper and lower together for a shooter. Both uppers were 100% with their original lowers but had malfunctions after the swap. I never did figure out why but suspected Colt had "covered up" something out of spec on one of the rifles by substituting a different buffer or something. Back then I didn't know about gas port sizes, different buffer weights, etc., so I just assumed something was out of spec somewhere and put the two back together as they came from the factory.

Ever since then I've made it a practice to shoot 200-300 rounds through and upper/lower combo before calling it good.

[WillBrink]

That was my thought when I read complete BCM upper and lower. A complete factory BCM may *may* have a better fit between the upper and lower than your gun does, but functionally there is nothing to worry about.

I effectively built an LMT SPM14 with a lightly used complete LMT upper and a complete LMT Defender lower. Saved a pretty penny doing it and ended up with a gun I can be rightfully proud of https://lmtdefense.com/firearms/spm14

The only thing you and I cannot do is honestly sell them as complete factory guns.

Andy

I don't really see why, as you and they put them together, push to pins, and done. If it were to different brands of upper and lower, maybe a consideration and perhaps some brands of uppers and lowers play nicer together than others, but I can't claim I have much experience in that area.