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Posted: 6/11/2015 1:20:36 PM EDT
| I just picked up a carbine, and the takedown pin has what looks like a screw head on the left side. The head looks like a normal pin. Is this suggesting a large hole upper? I havent messed with it other than to see the BCG is marked Colt, and is the crappy one with the firing pin exposed at the back end. At least it has what appears to be a dang near new Colt N1 stock. |
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I suspect they are. I guess I should take the screw out and see. But that would make sense.  It is a Colt carbine, marked Govt/military only.
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I suspect they are. I guess I should take the screw out and see. But that would make sense. It is a Colt carbine, marked Govt/military only.
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Are the pins the same diameter front and back? Mine are the same diameter, but Iirc, the front is longer than standard. Normal uppers interchange normally. |
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A friend of mine. recently purchased a "Used" Colt A3 HBAR Carbine, and it had the Front Pivot Pin with a Screw on the Left Side. It also had the Drain Hole (vent) in the "Fence" for the Front Pivot Spring & Detent Pin. Removed the Screw-on Pin and the Colt A3 Lower Receiver was ready to accept the Standard Front Pivot Pin, Spring & Detent, so I installed a Standard Colt Front Pivot Pin, Spring & Detent for him. I was surprised that it came with the Screw-Pin, and not the Standard Front Pin arrangement. But it was a simple fix, and he was very happy about the outcome. |
Colt switched to full fence lowers with small pivot screws some time in the Sporter II years. Some were drilled for the detent and spring so a standard push pin could be installed but mine, a restricted "assault weapon" from the ban years, was not. I sent it in to Ken at Specialized Armament a while back for his "Machine Lower Receiver for M16 Pivot Pin" package. Here's the before picture; after looks like any other standard lower with push pin.   |
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Quoted:
I just picked up a carbine, and the takedown pin has what looks like a screw head on the left side. The head looks like a normal pin. Is this suggesting a large hole upper? I havent messed with it other than to see the BCG is marked Colt, and is the crappy one with the firing pin exposed at the back end. At least it has what appears to be a dang near new Colt N1 stock. Just correct some verbage here. The takedown pin is located to the rear of the receiver and the pivot pin is at the front. The older Colts have a .325" opening for the pivot pin and they did use a screw to capture the pivot in place. This was generally because they had slabside lowers and there was no provision for a spring and detent to capture the pivot pin. Most all of the Colt SP1s and SPIIs are this way. Newer lowers have a .250" opening and the ones that have partial-fence and full-fence configurations allow for the use of springs and detents to capture the pivot pins in place. Newer reproductions of the slabside lowers require the use of a .250" pivot pin with a detent ball that snaps into the countersink on the left side of the front pin boss of the small hole (.250") upper receiver. |
Mine looks close to these pics, except mine says Tactical Carbine on the left side. And yes, JR, I guess my auto-correct keyboard misspelled "pivot" pin with "takedown" pin.  I looked closer, and there is no detent pin or vent hole in the fence. I reckon I will just leave the lower as is.
Quoted:
Colt switched to full fence lowers with small pivot screws some time in the Sporter II years. Some were drilled for the detent and spring so a standard push pin could be installed but mine, a restricted "assault weapon" from the ban years, was not. I sent it in to Ken at Specialized Armament a while back for his "Machine Lower Receiver for M16 Pivot Pin" package. Here's the before picture; after looks like any other standard lower with push pin. http://www.narruc.net/Public/pix/hbar/left.jpg http://www.narruc.net/Public/pix/hbar/right.jpg |
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