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Posted: 1/23/2023 12:44:42 AM EDT
[#1]
Quote HistoryQuoted: There is nothing different in a mil-issued upper versus the uppers that are on the market for the last 20 years. If it's an actual mil upper it's going to be 14.5 so would be pistol or NFA territory on barrel length. If it's 16 its just a random AR15 upper. At one time Colt made some uppers and bolt carriers that would not work on an FA lower, but it doesn't really mean anything, there is nothing an upper can do to make something be FA. The upper for an M16 has a relief cut for the sear to clear  Attached FileThis changes nothing functional or legal wise on the upper on a semi lower Colt made LOWERS and bolt carriers that would not work with full auto parts. The lowers had a sear block that wouldn’t allow for sear placement, drop in auto sears or lightning links. It was a chunk of metal in the lower  Attached FileThe bolts were “half moon” ones to clear the sear block and prevent the use with any full auto parts. They also had unshrouded firing pins  Attached FileAnd OP is talking M16 spec which would be a 20” pencil profile barrel |
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Posted: 1/23/2023 12:56:06 AM EDT
[#2]
Quote HistoryYes, you should...10+ years ago.  OP, as has already been said, guns shows, Gunbroker and the Equipment Exchange here on this site are probably your best bet for finding an original USGI upper. Search for terms such as M16, XM16E1, M16A1, 603, and 604 (these last two are Colt model numbers that are known & used by retro enthusiasts). More good info here: https://www.ar15.com/forums/AR-15/AR-15-M-16-Retro-Forum/123/ http://pullig.dyndns.org/retroblackrifle/ |
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Posted: 1/23/2023 1:17:55 AM EDT
[#3]
Quote HistoryQuoted: That’s an interesting gun. No fence lower and early 604 upper where the machining profile just below the port door matches the profile of the lower. That’s a desirable upper and whats the story on the lower? It’s large pin so is it an SP1 lower I assume? I know nothing about this gun other than it was presumably manufactured sometimes in the 70's. I bought it from a young guy that wanted to go all tactical and sold this to me instead of modifying it. 
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Posted: 1/23/2023 1:19:40 AM EDT
[#4]
Those SP1 kits going around 15 years ago were the best way...
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Posted: 1/23/2023 9:58:59 AM EDT
[#5]
Quote HistoryQuoted: There is nothing different in a mil-issued upper versus the uppers that are on the market for the last 20 years. If it's an actual mil upper it's going to be 14.5 so would be pistol or NFA territory on barrel length. If it's 16 its just a random AR15 upper. At one time Colt made some uppers and bolt carriers that would not work on an FA lower, but it doesn't really mean anything, there is nothing an upper can do to make something be FA. Quote HistoryQuoted: Quoted: I ran a thread on this Colt a while back. Is there any difference in the upper from a M-16? https://hosting.photobucket.com/images/q94/junker46/IMG_20221029_123407.jpg I know someone that has a 16" upper given to him from some 'special forces' friend. He is super paranoid about using it because he thinks it's a machine gun part. It looks like a regular carbine upper to me. Would there be anything different about a mil-issued upper? There is nothing different in a mil-issued upper versus the uppers that are on the market for the last 20 years. If it's an actual mil upper it's going to be 14.5 so would be pistol or NFA territory on barrel length. If it's 16 its just a random AR15 upper. At one time Colt made some uppers and bolt carriers that would not work on an FA lower, but it doesn't really mean anything, there is nothing an upper can do to make something be FA. The uppers work on a full-auto lower, if you remove the auto-sear. They skipped a shallow relief for it. The bolt carriers, likewise, work fine with a full-auto lower but don't have a rear face to trip the auto-sear. |
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