AR info, Colt upper, please help

[ballistic]

Can an older Colt SP1 upper be used on mil spec AR lower?
Would there be any issues putting it on a Stag, Mega, or LAR lower?
How about a newer Colt upper?

I have heard there differences with some/all Colt lowers that use larger pins for the trigger control parts. Are there any differences with the uppers?

Thanks.

[ivanimal]

I have a colt upper on a grizzly lower with no issues.

[xenophobe]

Can an older Colt SP1 upper be used on mil spec AR lower?
Would there be any issues putting it on a Stag, Mega, or LAR lower?
How about a newer Colt upper?

I have heard there differences with some/all Colt lowers that use larger pins for the trigger control parts. Are there any differences with the uppers?

Thanks.

If the pivot pin is a large hole pin, then you would need to get a bushing to use it with a small pivot pin lower. No biggie.

[ballistic]

I've got a Stag lower and want to use a Colt upper.
The Upper I am interested in is listed as -
Factory Colt SP1 - small hole (pivot pin hole?).
The seller says is will fit any modern AR15 lower, but I just wanted to get an imparital second opinion from someone with experience with these things.
Thanks again.

[C.G.]

I've got a Stag lower and want to use a Colt upper.
The Upper I am interested in is listed as -
Factory Colt SP1 - small hole (pivot pin hole?).
The seller says is will fit any modern AR15 lower, but I just wanted to get an imparital second opinion from someone with experience with these things.
Thanks again.

If it is the small hole upper, it should fit fine provided that your lower and upper are in spec.

[rorschach]

If its one of the A1 uppers that CDNN sells, it will fit your Stag lower. I have test fitted mine to a Stag and Lauer, and it fit both perfectly.

[bwiese]

Why anyone wants those old A1 uppers I dunno. They come with 1-12" twist 'pencil' barrels which are only good for up to 55gr ammo.

[6172crew]

Why anyone wants those old A1 uppers I dunno. They come with 1-12" twist 'pencil' barrels which are only good for up to 55gr ammo.

+1 Unless you have the lower to match I dont get it. It wouldnt be to much more to build the upper and have a barrel rigged in a more ammo freindly twist. I see SP1 upper receivers on AR15.com all the time, you would just have to find teh barrel and handgaurds Im guessing.

The Govt ditched the 1/12 for a reason, find a 1/7-1/9 at least you can shoot more surplus ammo if it ever becomes available later on.

[ballistic]

I understand some of you may not have any interest in the older upper.
A varmit upper, an M4 type, a DMC type match upper, and a long range, scope only upper all have their place.
I am perhaps older than many on this board and thought it would be cool to have a vietnam era looking AR. It would not likely be used as first line SHTF weapon. Don't think it will ever be a problem finding 55gr. 5.56/.223 ammo.

[6172crew]

I understand some of you may not have any interest in the older upper.
A varmit upper, an M4 type, a DMC type match upper, and a long range, scope only upper all have their place.
I am perhaps older than many on this board and thought it would be cool to have a vietnam era looking AR. It would not likely be used as first line SHTF weapon. Don't think it will ever be a problem finding 55gr. 5.56/.223 ammo.

No doubt the older GI uppers are cool, just the barrel needs to be changed out IMHO. If you can get a A1 stock it would look even cooler.: :

[rorschach]

Thats exactly what I plan to do, built a retro A1 type rifle. I have the A1 stock and grip, I'm just holding out for those pukes on ARF to get their Stag retro A1 lower deal squared away before I take the grinder to one of my lowers.