RE: buttstock end cap
Which one uses the the short top screw and
the longer bottom screw?

Quoted: A1 stock, being 5/8" shorter than the A2, uses the shorter, vented top screw.  I believe both the A1 and A2 use the same length bottom screw to secure the butt plate and sling swivel.

NOPE! The A1 stock has the longer bottom screw.  The screws are a different length because the A2 stock moves the sling swivel closer to the buttstock.

What is the advantage of the A1 over the A2? Just that it is shorter? I bought a New gun as an A1, (A1 front and rear sites) but I it came with the A2 Stock. What gives? Are A1 butt stocks no longer made?

M16A1 stocks are long gone as replacement parts in the Army, the M16A1 -23&P lists the same part numbers for stock, spacer, and screw as the M16A2.

The shorter stock is better suited for combat shooting then the longer stock, which was lengthened for USMC known distance range firing.  Neeless to say that's my opinon as the Army went with the longer stock as well.

-- Chuck

My reason for the question is functionality. I bought a Colt HBAR (A2 I presume). Then I replaced the furniture with with a old Colt wood set up. I put everything together but the bottom screw wouldn't engage the sling swivel (too short). Bought the longer one and thought all was well. Finally took the the rifle out to sight in the scope. When the range master called a routine cease fire, I discovered that the bolt catch would not engage, to hold the breach open. I managed the rest of my outing with a spent shell holding the breach open when necessary. Then came my cry for help from AR15.com members. The most simple trouble shooting method was to partially unscrew the top screw in the buttcap. Viola! Problem solved. My problem now is, I dont know if I relaced an A2 set up with an A1 or visa versa. From the look I got from the guy at the gun show when I bought the lower screw replacement, I want to be able ask for a A1/A2 upper buttstock buttplate retaining screw. Asking for the lower, stock cap, thinggy screw, longer than this one, just didn't go over well last time.    

I am looking for the longer lower stock screw for my A1 stock, where to get one without paying $6 for shipping?

Posted By Matt: I am looking for the longer lower stock screw for my A1 stock, where to get one without paying $6 for shipping?

Matt
I'm going tp a gunshow this weekend. Email me about picking one up for you