Colt SP1/M16A1 Uppers


Janos Dracwlya
December 20, 2006, 01:19 AM
I've been seeing a lot of these around lately - used ones taken off M-16A1s at gun shows and the ones CDNN had (they're now out). Since I've also been thinking about putting an AR together (not a full build, just buying an upper and lower, etc.), and, since everyone I shoot with has the M4-style AR's, I thought a retro M16A1-style gun might be fun for something a little different.

All of that said, will one of the Colt SP1/M16A1 uppers present any problems for me? Will I have to use a Colt lower, or can I use another type (say, a Double Star, for instance)? I've been doing some research here (using "search") and it seems like this should be no problems, but I'm not sure if I'm putting what I've been reading together the right way.


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December 20, 2006, 01:36 AM
The M16A1 uppers are "small hole" just like pretty much everybody makes. So doublestar should work. Mine's sitting on a Stag right now and it fits so tight it might as well be one piece of metal once it's all closed up.

You can get A1 grips and stocks online, but be warned ahead of time the A1 buttstock doesn't seem to quite fit an A2 reciever - it hangs a touch below the reciever in back. There's a few other little differences, but if your A1 is late enough it won't look too out of place on an A2 lower.

We may if we're lucky be seeing some A1 reciever repros on the market soon.

You'll prolly like the A1 once you start playing with it -- between the shorter buttstock, smoother pistol grip, and lighter barrel it handles delightfully well compared to the A2.

December 20, 2006, 02:02 AM
Count me in as another who would be interested in an A1-style upper. I've only seen the SP1 upper from CDNN and the A1 stripped receivers being sold.

December 20, 2006, 02:34 AM
Like so?

check out this thread -

No problems at all with the old Colt uppers.

Jeff White
December 20, 2006, 03:14 AM
Just be sure you realize that the A1 barrel has a 1/12 twist rate so you are pretty much limited to 55 grain ammo or some of the lighter varmint stuff.


Beetle Bailey
December 20, 2006, 03:22 AM
and the ones CDNN had (they're now out)

Oh, No! I was gonna wait 'til after Christmas to get myself one of these to build up! :eek:

Anyone know another place that sells them unfired in the cosmoline? TIA

BTW, I just want to shoot the 55 grain FMJ out of it, so the twist rate isn't a concern.

Dr. Dickie
December 20, 2006, 08:22 AM
I've only seen the SP1 upper from CDNN and the A1 stripped receivers being sold.

Where have you seen A1 lowers? I've been looking, but everyone sells A2 stripped lowers (I got one of the A1 uppers from CDNN to make a Vietnam area AR).

December 20, 2006, 10:57 AM
CDNN still shows the uppers on their web site. Am I missing something?

Dr Dickie, how does that upper look?


Dr. Dickie
December 20, 2006, 11:14 AM
When you click on the link to purchase, it tells you that they are currently out of stock.
jagd, they look like an M16:evil:

December 20, 2006, 11:27 AM
Dr. Dickie, I should have been more specific. Are they in truly like new condition? Hopefully they will get more in. I really want to build a SP1/A1 clone.


Dr. Dickie
December 20, 2006, 11:30 AM
I haven't taken it apart yet, but it looked NIB to me.
Problem is, you cannot get the proper looking lower. Butttt, since most of the "look" of the rifle is the upper, I guess any lower works (I have ordered the correct A1 Stock from Numrich Arms).

Janos Dracwlya
December 20, 2006, 11:41 AM
Thanks to everyone for their replies.

First off, I should have mentioned that this will be a gun with a 20 inch barrel, otherwise it would be a lot like the gun in those photos. That's a 16 inch barrel, isn't it? Or are my eyes a little worse than I thought?

The information about the barrel twist rate was very useful, but I was planning on mostly using 55 grain stuff anyway, though I will probably get some heavier stuff just to see the results for myself. Is the heavier stuff much more inaccurate at close ranges or just at longer ranges? Depending on my experiences once I get and start shooting the AR, I might consider rebarrelling to something with a 1/9 twist. We'll call that a learning experience.

Someone asked where I've been seeing these - I see a lot of well-used ones at the big gun shows in Louisville. They run $150-$200 or so depending on condition (no bolt, carrier or charging handle, but those are available, too).

Anyway, thanks for the information. And if anyone has anything else to add, please do.


December 20, 2006, 12:53 PM
Well, I called CDNN and the rep told me the A1 uppers were a closeout. Cheaper than Dirt has them, so I just oedered one from them. Ending up costing me about twenty bucks more for the same thing, but at least I've got one on the way.


December 20, 2006, 01:24 PM
Pangris, where did you get that handuard? I want one.

A stripped A1 upper can be had here:

Don't know where the barrel could be had though.

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