New 9mm build

I picked up a dedicated CMMG 9mm lower last month as a pistol lower. I swapped the pistol tube for a six-position stock tube and put a Magpul stock on it. I also got four mags, one Colt, one C products, and two unnamed others. Finding an upper for this lower was rough. Everybody was out of parts. Barrels could be found at various prices, but BCGs were all over the place price and availability wise. The only receivers were either .223 for reasonable prices or $200 9mm receivers. Ugh. I ended up looking in Gunbroker and found a guy selling complete 9mm uppers with bolt and charging handle for $399. It finally arrived today. It came with a 16" SS barrel, railed free floated handguards, a CMMG BCG, and some .223 upper receiver. And a flash suppressor. I put the two pieces togther. The upper receiver works but the lines don't quite line up. Everything seems to be working. I'm taking her on her maiden run tomorrow evening. All six mags (2 new ASC mags were purchased later) are loaded and ready to go. I have a cheap Tasco red dot on it just for testing. I'm swapping my Millet DMS-1 scope from my 3-gun rifle onto the 9mm rifle later this week after I get a new American Defense scope mount. I will be testing using Federal 9mm FMJs in 115gr and some of my 147gr lead reloads. I don't have extra JHP ammo to test, and I'm not buying anymore until next month. This is going to be a competition gun just to see if I can hang with the big boys in USPSA. We'll see how it goes. I'll post pictures up after I get the optics settled. And in case anyone is wondering, this rig cost me $750, including four 32-round magazines.

What made you want to go with a Colt mag setup over a Glock mag? I've got a Glock mag QuarterCircle 10 and it's nice, just trying to dial in ergonomics. What do you plan on going with for a muzzle device? I've got an A2 style flash hider on mine (bored for a 9mm), but plan on putting something more forward facing to direct the blast.

Tihsho said:

What made you want to go with a Colt mag setup over a Glock mag? I've got a Glock mag QuarterCircle 10 and it's nice, just trying to dial in ergonomics. What do you plan on going with for a muzzle device? I've got an A2 style flash hider on mine (bored for a 9mm), but plan on putting something more forward facing to direct the blast.

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Because if it's good enough for Colt, it's gosh darn good enough for me.

Tihsho said:

What made you want to go with a Colt mag setup over a Glock mag? I've got a Glock mag QuarterCircle 10 and it's nice, just trying to dial in ergonomics. What do you plan on going with for a muzzle device? I've got an A2 style flash hider on mine (bored for a 9mm), but plan on putting something more forward facing to direct the blast.

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I went with the Colt mag setup because I got the lower FTF with four 32-round magazines. I'm picking up this http://fortismfg.com/ar15-fortis-muzzle-brake-9MM-nitride-28 next month. I want more noise so the timer can pick up the shots when I shoot my next USPSA match.

j_h_smith said:

Because if it's good enough for Colt, it's gosh darn good enough for me.

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jimbobborg said:

I went with the Colt mag setup because I got the lower FTF with four 32-round magazines. I'm picking up this http://fortismfg.com/ar15-fortis-muzzle-brake-9MM-nitride-28 next month. I want more noise so the timer can pick up the shots when I shoot my next USPSA match.

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Make sure you measure the barrel threads prior to purchasing anything. My barrel for example isn't threaded for 1/2x28, I believe it's actually 1/2x36.

My barrel is 1/2x36, per the seller. So this is the one I want http://fortismfg.com/ar15-fortis-muzzle-brake-9MM-nitride-36 Same price.

Glock mags also go in at an angle where the colt mags are vertical.

Gambler said:

Glock mags also go in at an angle where the colt mags are vertical.

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Colt mags are cool. That's all that needs to be said...

Personally I went with the Colt pattern because I used a Colt upper. To use a Glock lower I would have needed to replace or machine the bolt.

For anyone looking to build one A1 Uniform has a YHM lower in stock and a few used Colt SMG uppers.

Tihsho said:

What made you want to go with a Colt mag setup over a Glock mag? I've got a Glock mag QuarterCircle 10 and it's nice, just trying to dial in ergonomics.

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just my two cents, but i went with a QC10 Colt lower because my in-progress 9mm AR build is a pseudo Colt SMG concept.

Colts just look cooler.

A few thoughts:

- Colt vs. Glock magazine lowers: Going with Colt mags makes sense from a training perspective since they insert the same way (vertically) as standard AR-15 magazines. Going Glock means a different motion due to the angle. Not everybody cares but that's why I went with Colt pattern for mine.

- Muzzle threads: 1/2-36 is often used on 9mm AR barrels so guys won't accidentally stick a .22" bore muzzle device over a .355" sized barrel. That would fit but would not end well.

DutchV said:

A few thoughts:

- Colt vs. Glock magazine lowers: Going with Colt mags makes sense from a training perspective since they insert the same way (vertically) as standard AR-15 magazines. Going Glock means a different motion due to the angle. Not everybody cares but that's why I went with Colt pattern for mine.

- Muzzle threads: 1/2-36 is often used on 9mm AR barrels so guys won't accidentally stick a .22" bore muzzle device over a .355" sized barrel. That would fit but would not end well.

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I went with a 13.5x1 LH(Euro thread). Two reasons; 1) My can already came with that thread pitch adapter already on. 2) and the biggest reason is, left hand threading for suppressors helps prevent them unscrewing while shooting caused by the vortex from bullet spin direction.

First, I'm going to note that I did not assemble the upper or the lower. The lower was assembled by someone else, and the upper is a factory upper I got off of Gunbroker.

I took her out for her maiden voyage today. I'm glad it's not a boat. I was using Federal 115gr FMJs for testing. Using the first ASC magazine the bolt held open with half the magazine still full. I then tried the Uzi, Colt, and C-products mag and they did the same thing. Halfway through the second magazine, the handguard loosened up. I finished up with about 150 rounds downrange. I talked to the manager of the shop about it. He took a look and advised that the bottom screw holding the rail on was loose and how to fix that problem. And apparently, the bolt catch spring wasn't working right, so I had to get my punch set out and take it off. It turns out that the metal around the detent had crept into the hole and prevented the detent from extending out keeping the bolt catch from catching the bolt. I managed to scrape the metal out of the way so it's working now. On a positive note, it ate the Federals and my 147gr LFP ammunition with no issues.

Glad to hear that you worked out the kinks.