CMMG Colt pattern dedicated 9mm AR Lower Receiver build.

[Skullworks]

Hidden in the back of the safe since 2001 I have had a NIB complete Colt CAR-16/9mm upper assy. What better time than the present to finally get it out and ready for action.

Now there is no shortage of companies ready to sell you some sort of mag block set to convert your normal (223) AR type receiver to accept some type of 9mm magazine. There are drop in the top types, drop out the bottom types, units which use the 223 mag latch to retain the adaptor with a second mag latch to use the original Uzi mag latch cut out. Some units like the OEM units used by Colt are a semi-perm install as they are pinned in place with roll pins. Most people are loath to be drilling holes in the receiver and I would not recommend it either.

Looking at all these options they all have 2 things in common. They require an existing AR receiver and when you add up all the (S)hipping, (H)andling, (I)nsurance, and (T)axes its going to cost you well over $150 for the adaptor parts.

CMMG now solves this headache with a simple elegant solution. They offer a custom machined lower receiver which has the mag well cut to fit the Colt/Uzi pattern mags. They also have the Colt style ejector pinned in place and the extended finger bolt catch installed that will work with the OEM Colt mags and some aftermarket mags.

The build is almost identical to a normal 223 build except you will not need the 223 bolt catch or its plunger, spring and roll pin as CMMG has pre-installed the required 9mm parts for you.

I used a Palmetto State Armoury Classic LPK ($49.95) because it supplies a rounded faced hammer. WARNING - The Colt 9mm Bolt will not function with a notched face AR-15 hammer, this will jam the action and require pulling the takedown pins and freeing the bolt from the hammer. (not fun)

For the stock I dug out a M16A1 takeoff that was in near mint condition as I prefer the shorter (no spacer required) OAL. This also matches up well visually with the A1 style upper used by Colt for this CAR-16 barrel assy. The receiver extension, rifle buffer and spring are all standard 223 parts. NOTE: Had I chose to go with a telescoping stock, such as a M4 6 position a special buffer/spring combo would be needed. Keep in mind that the 9mm is a straight blowback design and that buffer weight and spring rated are critical to proper function.

CAREFUL WITH THAT AXE EUGENE !

Its true - Stoner never intended the AR to be a blowback pistol. All the design mods to make this work were hacks after the fact... In fact Olympic arms actually came up with the first "working" 9mm conversion, There are pros and cons for each system, and each has there fair share of fan boys and critics.

Other than the noticeable difference in magazine size and the less noticeable shorter dust cover door this AR has the same look, feel and function as any other 223 AR. All the controls are in the exact same locations and behave as expected. This is the "pro" that most Colt Coolaid drinkers will preach. This point does hold merit.

Perhaps the biggest flaw for non-Colt pattern or hybred Colt pattern is the "hunt for the mag release" - many other configurations relocate the mag latch and some conversion blocks will actually drop the entire mag block adaptor if you use the OEM mag release button. This can be bad news under a high stress encounter (arn't they all?)

Oly addressed this issue by welding spacers directly to mags such that the top of the mag fit the AR mag well... OK - But what kind of a mag pouch are you supposed to put those mags in?

Don't get me wrong - The Oly system can be customised to work for you just fine. In fact I hope to do a scratch build of an AR45 sometime late next year - assuming all the parts are not restricted by then...

OK - the Bottom line. This build went together flawlessly. I stepped out side and ran a mag through it and I must say this is as good as any Colt 9mm LE offering out of the box. NOW THE BEST PART - THIS RECEIVER COST ME $153 - Possibly less than a mag block set from other vendors. So unless your going to use the excuse there is no more space in the safe - this is an option you should explore.

BTW - The Serial numbers are prefixed "SMG-"