CMMG 9mm Colt mag lower

[sigstroker]

I acquired one of these a few years back, in part because I love the steel Colt mags. I had a Colt 9mm AR carbine so long ago it ended up being called "pre-ban", and really liked the mags. Double feed position and easy to load, and stout enough to beat the enemy to death if you run outta bullets. Plus they are a lot like the mags my old Uzi used.

At any rate I had left the CMMG lower sitting, because that's what I do with most of my gun stuff. Recently I tried putting actual parts in it to build it out. I couldn't help but notice the fire control pins are SMALLER than normal. Has anyone heard of that? I've heard of the larger than normal pins that Colt used to us, but not smaller.

[beanz2]

Hmmm. I have a CMMG Mk9 which also takes a Colt mag. I have swapped the trigger with no issues with a Hiperfire AR trigger with its own trigger and hammer pin. Maybe yours is just new with tight virgin holes?

[Spyder]

Ya, my thought is just extra tight?

I love the Colt SMG style, but glock mag guns are just better. I've got a glock mag 40 s&w AR and a couple variations of 9mm. All are way gun.

[Tripplet918]

Found below online.

“For Colts, there are .170 pins.

They switched to .154 FCG pins in the first part of 2009.”

[sigstroker]

Hmmm. I have a CMMG Mk9 which also takes a Colt mag. I have swapped the trigger with no issues with a Hiperfire AR trigger with its own trigger and hammer pin. Maybe yours is just new with tight virgin holes?

No, it's not really very close. I might have to contact CMMG on Tuesday.

Ya, my thought is just extra tight?

I love the Colt SMG style, but glock mag guns are just better. I've got a glock mag 40 s&w AR and a couple variations of 9mm. All are way gun.

Why are Glock mag guns better? I have one of those too. Crappy plastic mags with single position feed.

[Scooooter7]

No, it's not really very close. I might have to contact CMMG on Tuesday.

Interesting, let us know what they say. Recently ordered the Resolute MK9 but waiting for it to arrive.

[smle-man]

My son was issued a Colt 9mm SMG at his agency. He said it was a great little gun and preferred it to the short barreled AR full auto 5.56 guns they switched to.

[sigstroker]

I had another thought, so I dug the lower back out. Sure enough, on one side there's no hope of getting the fire control pins in. But on the other side, it's just a very tight fit. It's not the end of the world if I can only push them in from one side, but it sounds maybe like they weren't reamed on both sides. I guess it would be okay to just chase the holes with a 5/32 drill bit? I don't know if I even have one.

[loademup]

I've read that Colt change the diameter size to larger fire control pins back in the early 1990's as one of the measures to prevent people from putting in surplus full auto parts. I have a CMMG Mk 9 LE and absolutely love the gun.

[beanz2]

I had another thought, so I dug the lower back out. Sure enough, on one side there's no hope of getting the fire control pins in. But on the other side, it's just a very tight fit. It's not the end of the world if I can only push them in from one side, but it sounds maybe like they weren't reamed on both sides. I guess it would be okay to just chase the holes with a 5/32 drill bit? I don't know if I even have one.

CMMG has been responsive to customer's issues in the past for me. Maybe it is best to ask them to correct the problem. If the holes you drill are off center, or too large, that can ruin the lower.

OTOH, if you must do it yourself, I'd grab an 80% build jig to make sure the holes line up correctly.

[sigstroker]

I left them a message.

80% jigs are not easy to find any more, and 9mm jigs nearly impossible. Although, the Mk9 mimics the Colt carbine somewhat so maybe an ordinary 5.56 one would work.

But I think just using a drill by hand would probably work. I could feed it in from the other side so it would be straight.

[Spyder]

That's odd to find on a factory piece. Curious what they have to say about it now, and I'm sure they'll offer some sort of fix.