The title kinda says it all. I have a 1978 Colt SP-1 carbine that is in good shape overall. At some point in its life, I believe the bcg was replaced because it’s not C marked and looks like a more modern type bcg. I’ve seen that retro rifles sells replica a moderator and grenade ring. Thoughts on this project? I’d have to get the barrel cut to 11.5” and get the moderator installed, might have to open the gas port a little. Is this a stupid idea to do this to an old Colt? Should I just try and find the correct bcg and get it as close to original as possible?

If you have some spare cash, you should seek out one of the Colt commemorative reissue version with a US property roll-marked lower, the partial fence and with selector stop humps...the rest of the rifle is built from new production parts so nothing to write home about, but the lower assembly to include the metal stock is where it really shines.

It's not the cheapest thing but this allows you to cut the upper to your hearts content without feeling too bad, heck just throw on a real GI upper if you can find one for that ultimate build, it'll drop right on since it uses the milspec pivot pins as opposed to that weird Colt large hole setup on their early sporters that isn't compatible with the real GI stuff let along anything else.

AND you get to do this all while avoiding cutting up an original SP1 Carbine.

quote:

Originally posted by darkest2000:
AND you get to do this all while avoiding cutting up an original SP1 Carbine.

Yep.

Or, Brownells offers a XM177/GAU-5A clone.

https://www.brownells.com/.asp...Page/brownells-177e2

Keep the original, buy a new replica. Cutting up an original SP1 is kinda like cutting up an original Camaro at this point. IMO

quote:

Originally posted by Syngin1066:
The title kinda says it all. I have a 1978 Colt SP-1 carbine that is in good shape overall. At some point in its life, I believe the bcg was replaced because it’s not C marked and looks like a more modern type bcg. I’ve seen that retro rifles sells replica a moderator and grenade ring. Thoughts on this project? I’d have to get the barrel cut to 11.5” and get the moderator installed, might have to open the gas port a little. Is this a stupid idea to do this to an old Colt? Should I just try and find the correct bcg and get it as close to original as possible?

don't,

please

just build another,

that 1978 vintage CAR is worth a bit,

I wouldn’t.

Please, please…. Don’t cut up or part out that SP1 carbine. Like others have said. Plenty of clones out there. Or, with all the original and repro parts out there to build one. If you got the time and the inclination build one. It is fun.

Do not mess with your SP1. Buy a Colt retro GAU.

Yeah, you guys are right. I’m not going to mess with it. Now, I need to track down the correct bcg.

quote:

Originally posted by Syngin1066:
Yeah, you guys are right. I’m not going to mess with it. Now, I need to track down the correct bcg.

There were a couple on Gunbroker of recent.

The Colt retro GAU also is one of the very few on the market with 1/12" twist rifling, which when firing 55 gr M193 ammunition has interesting terminal effects.