AR Lowers questions

[Lovesbeer99]

I can see how the uppers on an AR can differ, barrel, chamber, bolt, etc.
But on the lower, other than the trigger group, how are the lowers different?
How is 1 lower better than another? Can I just use my BM lower and build an National Match Upper?

Thanks in advance
Lovesbeer99

 

[W.E.G.]

One of the things I have noticed is "sprue lines."

Some can be really jagged. Indeed, this is cosmetic, but who wants a crummy-looking receiver.

I have also noticed some variation in the thickness of the lip around the mouth of the mag well. Didn't seem to affect function.

 

[MMcfpd]

Your forged Bushmaster lower ought to be fine. There's very little real difference between the forged lowers available, as long as they meet spec, and most do. Problems people occasionally encounter seem to include off-size or misplaced holes and difficulties with fitting/releasing certain magazines from the magwell.

 

[Coronach]

Basically, a lower is a lower is a lower. The main differences are the logo and the price tag. As was stated, there are some cosmetic differences and some minor variation in non critical areas, and occasionally a maker will churn out crap that is not to spec in critical areas (holes misaligned or the wrong size, metal that is poorly forged or cast) *cough*Hesse*cough*Vulcan*cough*, but by and large lowers are the same. You may be very surprised how many lowers are exactly the same and came from the same line, just wear different logos.

Mike

 

[strat81]

Your BM is fine. Otherwise, stick with well-known brands such as Stag, RRA, Doublestar, Superior, DTS, Spikes, Mega, Noveske, LMT, etc.