Colt 9mm A1 Receiver

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[ARCHIVED THREAD] - Colt 9mm A1 Receiver

Posted: 8/26/2015 11:43:01 AM EDT

My question is.....Was an early forging Colt 9mm CM receiver machined for a gas tube?

Here's the deal, I purchased a receiver on GB advertised as an Early XM Gray A1 "CM" Forged Colt 9mm Receiver. Some detail without posting a picture, It's a CM forged, Slick Side, small pivot pin hole, 50 MM marked sight window, has the short 3/4 9mm port door and the 9mm gas blow back/Shell deflector. Other than the 9mm features, it looks just like a SP1 receiver with a small pivot pin hole, the casting lines...line up with the lower receiver magwell like an early receiver would as well.

But to my surprise when I opened it up, It has been machined for the gas tube as well as the cam key, which my later A1 Colt 9 mm receivers are NOT. So I'm trying to figure out if it's a true 9mm receiver as advertised? Which prompts my original question....Was an early forging Colt 9mm CM receiver machined for a gas tube?

Posted: 8/26/2015 1:25:35 PM EDT

[#1]

I think it's more likely that you have a 5.56mm upper that was converted to 9mm rather than a purpose built one.

Posted: 8/26/2015 1:40:15 PM EDT

[#2]

Quote History

Quoted:
I think it's more likely that you have a 5.56mm upper that was converted to 9mm rather than a purpose built one.

View Quote

Yea that's what I was thinking. The seller replied back that he was the original owner and he bought it New back in the day as a Green Label 6450 Colt 9mm. He does have low feedback on GB but so do I and I hate to call BS. I was thinking all purpose built original Colt 9mm would NOT have been machined for the gas tube as well as boss machined for a cam key.... Naturally if pictures would have shown the front of receiver, I would have questioned before using the buy in now. It's a nice receiver, I just want what I paid for.....nothing more, nothing less.

Posted: 8/26/2015 1:55:36 PM EDT

[#3]

It's possible that Colt may have originally used a converted upper for a factory rifle, but from everything I've heard here their 9mm uppers were all purpose built without cam pin or gas tube cuts.

Posted: 8/26/2015 8:19:01 PM EDT

[#4]

My Colt 9mm upper has no gas tube hole or cam pin cut. I figure it would have been cheaper for Colt not to machine those areas.

Posted: 8/26/2015 9:12:06 PM EDT

[#5]

Quote History

Quoted:
My Colt 9mm upper has no gas tube hole or cam pin cut. I figure it would have been cheaper for Colt not to machine those areas.

View Quote

How old is yours? I have modern colt 9's that are not machined.

Posted: 8/26/2015 11:13:22 PM EDT

[#6]

My 9mm Colt had no gas tube hole. I suppose it's possible, even likely that an early one would be the same as the 5.56 - you can see pics that they didn't shorten the ejection port door right away and add the bumper - early 635s looked like normal 5.56 guns... I just don't know for sure. A 5.56 upper will work just fine, but how do you know it's a "9mm" upper and not just another 5.56 upper if that's true?

Posted: 8/28/2015 3:15:18 PM EDT

[#7]

After much conversation with the seller, I truly think this is just another case of Colt just using an on-hand upper to complete the 9mm build. I don't see someone building a 9mm and search out the 9mm sight window as it really would not be needed.

If it isn't a 9mm I really don't know what it would have been, basically the same receiver as a early 1st addition 604 (Magwell forge lines, lining up with the lower receiver's magwell lines) but it does not have a rebated front lug.

I'll get some pictures up over the weekend for inspection......

Posted: 8/29/2015 9:15:49 PM EDT

[#8]

Pictures...

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Posted: 8/29/2015 9:41:07 PM EDT

[#9]

I've had several older Colt 9mm's that had the gas tube hole and cam pin recess machined. I also had one with just the cam pin recess machined and no gads tube hole. I think your seller is being honest.

Posted: 8/31/2015 9:07:41 PM EDT

[#10]

I have both an '86 era transferrable Colt 9MM SMG, and a modern era Colt 9MM SBR. Neither receivers have the machined hole for the tube. I have never seen one with.

Posted: 9/2/2015 7:10:17 PM EDT

[#11]

This may not be a good indicator of anything, but how does the gas tube hole look? Is the annodizing unmarred like there has not been a tube through it? Just a thought.

Posted: 9/4/2015 9:13:22 AM EDT

[#12]

The first picture is the most interesting to me. It has a CM forge mark, yet the lip behind the ejection port has the cut out that lines up with the lower magwell.

Posted: 9/4/2015 4:21:45 PM EDT

[#13]

When I was with a sheriff's office in Florida we had some very early full auto 9mm versions on load to try out against our MP5's. I remember taking them apart and found them to be converted standard no FA uppers. They had parted added to them to use 9mm and didn't appear to be purpose machined uppers. If I recall properly the lower had an insert for the magazines.

I would think your upper is similar part, looks like the ones we had.

Posted: 9/4/2015 4:45:46 PM EDT

[#14]

Quote History

Quoted:
The first picture is the most interesting to me. It has a CM forge mark, yet the lip behind the ejection port has the cut out that lines up with the lower magwell.

View Quote

SP1 uppers did that sometimes. I always wondered why they used the earlier dies and added the forge code.

Posted: 9/5/2015 4:45:47 PM EDT

[#15]

It's forged like an SP1 upper but it has a small pivot pin

Posted: 9/5/2015 7:14:29 PM EDT

[#16]

One more post from me on the upper, I'm 100% convinced that is was a purpose built colt 6450 9mm. Rencently the original owner sent me some pictures of the 6450 lower, as well as some older pictures of it complete with the upper that I purchased. He is actually trying to sale the lower as well, but Currently it's registered as a SBR, with suppression. Said he wished he would have left the gun intacted years ago. He wanted to see if I was interested in the lower, shortened barrel, suppresser,etc. required two stamps....with a crazy price

Posted: 9/6/2015 2:21:00 PM EDT

[#17]

I also believe that upper was intended to be a dedicated 9mm upper. Colt, as we all know, had a history of oddball parts.
Here is a picture of mine with a small pin, CM 9mm upper with the cutout behind the ejection port lip. Maybe the CM 9mm uppers
were cast on the same die as the SP1 uppers and the SP1 uppers just had the large pin routed out?

[ARCHIVED THREAD] - Colt 9mm A1 Receiver

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