View Full Version : Significant Difference Amongst AR Lower Receivers?

Scatch Maroo
11-28-2005, 4:38 PM
Found answer in other thread. :-)

Scatch Maroo

11-28-2005, 4:50 PM
Originally posted by BWiese:

bwiese (http://www.calguns.net/calgunforum/member.php?u=191) http://www.calguns.net/calgunforum/images/statusicon/user_offline.gif vbmenu_register("postmenu_179837", true);
Senior Member
Join Date: Oct 2005
Location: San Jose
Posts: 256

Originally Posted by Ravenslair
I am looking for the best AR receiver NOT listed in 12276.
{snip....} Thanks for your input.

I'm about to commit heresy here, but I will say that, for quite some time, most all AR lower receivers are just about the same for all practical purposes.

The overall AR design really doesn't put strong demands on the lower receiver. AR15/M16 design improvements over the original M16 strengthened things even more. And as long as it's strong enough in the rear receiver ring lug for 'buffer tube' (receiver extension), and all the holes are drilled to spec positionwise & sizewise - and in proper relationship to each other - you're OK.

The AR can be amazingly accurate even w/a sloppy, wiggly loose fit between upper & lower receivers. If you're gonna make your AR shoot nicely, the last thing you should look at is upper/lower fit - far better to first go for a free-float barrel, get a good barrel, a decent trigger, use match ammo, etc.

Since magwell dimensions are not highly specified some folks report problems with certain mags in certain guns (usually, swollen Orlite mags in Bushmasters, which have tighter-than-usual magwells). This is very very rare however, and is actually likely the mag's fault (some plastic Orlites can 'swell' fully loaded and bind in magwell; this can cause feed issues too. Gluing some plastic sideplate shims on sides of Orlites stops this.)

Now, some Rock River Arms upper receivers are reputed to have very, very tight - almost unusable! - fitment with generic AR lowers. Hard to drift out or reinsert the rear takedown pin, hard to seat the upper with lower, etc. This actually makes me wonder about the converse situation: if Rock River Arms lowers would have too-tight fits with non-RRA upper receivers.

There were some QA problems in 1990s with some cast Olympic Arms lowers. I think that has disappeared as many folks have had Oly upgrade these from cast to forged (retaining serial#); many Oly guns w/cast lowers were rushed out the door before 1994 AW ban.

As it is, many/most lowers seem to come out of just a couple of forging houses. As long as the coating is milspec you should be good to go.

Some lower-cost brand lowers may have a bit of coating debris in some of their holes, esp detent pin holes. This can be readily cleaned out with a drill bit by hand (don't use power!).

One key thing to check out w/AR lower vendors is their replacement policy. The actual warranty issue is far less important than whether or not the vendor will do the requisite ATF bookwork so a damaged/worn lower can be replaced with a new lower with exact same serial#. [This is obviously important to Californians, even from a non-assault weapons standpoint, since new serial numbers essentially need to be re-DROSed with fees and another 10 day waiting period; it'd be especially important for handguns not on approved 'safe gun' list, but I haven't heard of handgun vendors doing S/N reissue....]

There's probably teeny-tiny things in ultramatch grade ARs that ultra-high-quality lower/AR mfgrs offer. And I think there's some folks making steel lowers too - but I'd not wanna lug one of those around, that's strictly for a benchrest gig.

I have both (legal, registered) Colt and ASA lowers. I wish I could trade the Colt lowers for more ASAs - and that's saying something, because I wouldn't spit on most ASA products due to reputation. Nevertheless the ASAs are finished beautifully and work 100%, and use milspec fire control parts. This is very unlike my Colt postban lowers: these damned things require special Colt fire control parts, have a sear block preventing good trigger kits or the Chip McCormick trigger module from being installed. These Colt lowers were also not drilled for a detent pin for front pivot pin - meaning you gotta use that weird 2-screw front pivot pin and can't readily break down your gun into two halves.

So, if you have a chance to get an AR lower (either assuming you are going 10rd fixed-mag route, or saving for a rainy day when it's declared as an assault weapon) get a lower. Get any lower - it's mostly irrelevant, even for really accurate rifles. That's the beauty of the AR system.
Bill Wiese
San Jose

And here I spent all this time looking for Bill's excellent summary.

Scatch Maroo
11-28-2005, 5:00 PM
And here I spent all this time looking for Bill's excellent summary.

Effort was appreciated, but I found the same post. ;-)

Scatch Maroo