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1/25/2018 7:38:29 AM
Posted: 12/25/2002 7:23:08 PM EST
[Last Edit: 12/25/2002 7:54:24 PM EST by BlueDevil]
I need information on a SP1 type upper that came on a preban EA lower. The upper has a 16 inch barrel, bayonet leg, with a military style 3 prong suppressor. The upper has forward assist but no case deflector. Under the A1 sight adjustment wheel has P M in raised letters. Does anyone know who manufactured the upper.

Link Posted: 12/26/2002 2:16:49 AM EST
That certainly doesn't sound like a factory configuration to me. I'm not sure about the P, although the M usually means the upper was forged by Martin Marietta. All SP1 carbine uppers were large-hole pivot, slick side with no forward assist. They also came with an A1 birdcage flash suppressor.
Link Posted: 12/27/2002 5:10:21 AM EST
This is pure speculation, but P M is not a Colt marking. It might, however, be a govt contractor marking on a unit that had the front pin hole opened up for the large screw. Incidentally, I was unaware that anyone but Colt ever made a large screw lower. Learn something every day, I guess. [:D] As it happens, I just acquired a forward assist Colt upper reciever with a large SP1 type front hole. The letters under the rear sight are C H and the Colt proof marks are stamped just ahead of the ejection port. The forward assist is not the teardrop type, but the early large button with the flat milled on the inside. Since the flat was milled in to clear the increased dimension at the rear of the A2 type lower, I guess the thing was originally one of the early commercial A2 types. I know that Colt spent several years selling ARs that still had A1 sights, after the adoption of the A2, but I didn't realize that they were still using the large pin fronts at that point.
Link Posted: 12/27/2002 11:01:48 AM EST
Link Posted: 12/27/2002 7:14:41 PM EST
[Last Edit: 12/27/2002 7:20:49 PM EST by BlueDevil]
Originally Posted By Troy: BlueDevil hasn't stated whether the upper has a large, SP1 pivot hole or a small, standad-size pivot hole. If it's the latter, it's an M16A1-style upper reciever, not an SP1. -Troy
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It has a standard size pivot hole. The 16 inch barrel is larger in diameter under the m4 type handgards and smaller in diameter up to the threads where the suppressor is fastened. The bolt carrier and bolt are make by Colt.
Link Posted: 12/27/2002 7:50:20 PM EST
Link Posted: 12/28/2002 7:28:18 PM EST
No, there are no markings of any kind on the barrel. Bluedevil [devil]
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