Hi Ya'll
How have AR Receivers (for civilians) changed since 1980, if at all?

Other than the old slabsides, I realy dont know of any significant changes to it.

So the Goof-Ball AWB of 94 did absolutely nothing to change the internals?

I dont think the AWB did... Although Colt did change the inside of the receiver to keep theirs from working with full auto parts... Also the takedown pin sizes were different for later Colts I believe... cant remember exactly though..

there have been a couple of significant redesigns in the basic AR/M16 lower since 1980.  you can't really talk in terms od Colt's change from the SP1 and 2 series, because all Colt was doing there was using up some very early reciever forgings that were never adopted for use in the M16.  

The early M16s and M16A1s used a lower that had a 90% angle at the bottom of the front mounting lugs, rather than the rounded curve that you see on all current models. The rear ring area was without the reinforcement hump that goes around the ring area, and is blended into the rear of the reciever body, ending at the rear takedown pin hole. And of course the very earliest M16s didn't have the mag release guard

These changes were primarily done because M16's and A1s had a distressing habit of breaking there when rifle grenades were fired.  Early aftermarket lowers copied the M16 pattern for the most part, rather than the smoothside SP1 lowers, so a good condition early aftermarket type lower is a desirable item for those of us who want to build up M16 and M16A1 clones.  Current type lowers  just don't look quite right with our early type clones.  

So when you think about changes in the lowers on ARs, don't just think about the SP1 to current A2 style changes. There are beaucoup non Colt early lowers out there which more or less follow the A1 style, including the current push pin front hinge-----and I wish some smart maker out there would do  a production run of A1 types.  With all the milsurp uppers and barrels out there, a lot of us would jump on the opportunity to get lowers that match our Air Force and Army surplus uppers

Where can someone purchase surplus AR uppers?  I'm sure that this is an old thing, as I remember seeing DRMO slice up barrels of stuff not reutilized by the military prior to public auction.

Quoted: Where can someone purchase surplus AR uppers?  I'm sure that this is an old thing, as I remember seeing DRMO slice up barrels of stuff not reutilized by the military prior to public auction.

Been seeing them at gun shows here in Georgia for the past couple of years; both M16 and M16A1 uppers and barrelled uppers. CDNN has been selling brand new M16A1 barrelled uppers for almost a year now.

www.cdnninvestments.com

Also, check out the Used Parts section of the EE forum on this site.

It seems that cutting up the assemblies for scrap stopped when the Bush administration came in; because in the past three years I've been able to buy both Air Force surp M16 and Army surplus M16A1 uppers,  barrels, stocks and bolts/carriers----in fact everything but the lower recievers.

As I noted in my first reaponse, there are a bunch of us who have been able to build up M16 and M16A1 clones with this stuff----except for having to use the current A2 profile lowers, or shell out for a preban lower.

Hi there, I'm new to this group, but have a question on AR15 lowers too.  I agree that Colt blocked the receiver and changed some of the pin sizes so that M16 parts could not be used.  But I thought that most if not all lower receivers where changed so that full auto parts could not be installed without milling the "block" out.  Is this correct?  Are there receivers on the market that are not blocked so that if you were allowed a Class 3 weapon that you could modify and install the full auto parts?