9mm AR Upper

[BigDiezel]

Yeah, I don't mind. Just shoot me a message.

 

[Super Dave]

You're money ahead with a CMMG upper. Their bolt is better. I started with a RRA upper, and their Colt style hammer. When I switched to the CMMG ramped bolt, and normal NOT notched hammer, it got smoother. I run a Spikes ST-T2 buffer, not the heavier 9mm buffer, and a spacer in the receiver extension. I also use Spikes' mag block which is actually made by Hahn. The ejector is adjustable. Resist the temptation to buy the cheap plastic mag block. Plastic is for grips and hand guards. Not mag blocks, receivers, or magazines.

My 9mm AR is my favorite. They're totally awesome!!!

 

[Jedabug92]

You're money ahead with a CMMG upper. Their bolt is better. I started with a RRA upper, and their Colt style hammer. When I switched to the CMMG ramped bolt, and normal NOT notched hammer, it got smoother. I run a Spikes ST-T2 buffer, not the heavier 9mm buffer, and a spacer in the receiver extension. I also use Spikes' mag block which is actually made by Hahn. The ejector is adjustable. Resist the temptation to buy the cheap plastic mag block. Plastic is for grips and hand guards. Not mag blocks, receivers, or magazines.

My 9mm AR is my favorite. They're totally awesome!!!

Cmmg dedicated?

From my sniper hide

 

[Jedabug92]

To shoot the 9mm upper what do I have to do to my lower?
I'd like to build just the upper

From my sniper hide

 

[Cavedweller]

I tried the Hahn mag block method with an Adco 10.5" 9mm upper w/ ERA ramped bolt on a SBR'd lower. I could never get it to run 100% and it soured me on 9mm conversions. I recently picked up a CMMG MK-9 that has a dedicated lower and it has been 100% reliable so far and is a blast to shoot. So that said I would just spring for the dedicated lower.

 

[becker_atc]

Qc-10 I think is what it called takes glock mags


Sent via message in a bottle

 

[Super Dave]

To shoot the 9mm upper what do I have to do to my lower?
I'd like to build just the upper

From my sniper hide

So long as you don't have a notched hammer, you just need the mag block, and a buffer spacer, and maybe a heavier buffer.

Colt originally had a heavier buffer in the 635, but some guys like a normal buffer. Like I said, I run a ST-T2 buffer. Heavier than stock, lighter than the Colt 9mm. Spikes sells a 9mm buffer, but it was actually a tech guy there that sold me on running the ST-T2.

After playing with my ejector height, I have never had any problems other than running out of bullets. I may be using a heavier buffer spring, but I just can't recall. The spacer also makes for greater spring tension.

Google notched AR hammer and 9mm you'll see what I'm talking about. I know RRA's hammers are notched. I believe CMMG's are not.

My 9mm is a pistol with a Sig arm brace, although I have only used it on my arm once, for S&Gs. I have another upper that I am almost finished with that is 223 Wylde to swap out as I like. I just have to take out the block, pull the buffer and spring to remove the spacer and pop the spring and buffer back in, and I am ready for long skinny boolits.

 

[Jedabug92]

So long as you don't have a notched hammer, you just need the mag block, and a buffer spacer, and maybe a heavier buffer.

Colt originally had a heavier buffer in the 635, but some guys like a normal buffer. Like I said, I run a ST-T2 buffer. Heavier than stock, lighter than the Colt 9mm. Spikes sells a 9mm buffer, but it was actually a tech guy there that sold me on running the ST-T2.

After playing with my ejector height, I have never had any problems other than running out of bullets. I may be using a heavier buffer spring, but I just can't recall. The spacer also makes for greater spring tension.

Google notched AR hammer and 9mm you'll see what I'm talking about. I know RRA's hammers are notched. I believe CMMG's are not.

My 9mm is a pistol with a Sig arm brace, although I have only used it on my arm once, for S&Gs. I have another upper that I am almost finished with that is 223 Wylde to swap out as I like. I just have to take out the block, pull the buffer and spring to remove the spacer and pop the spring and buffer back in, and I am ready for long skinny boolits.

I'm assuming you have to have the buffer spacer

From my sniper hide

 

[Super Dave]

Yes. I made mine, but I think they are $5 or $10 from Spikes.

 

[Jedabug92]

Yes. I made mine, but I think they are $5 or $10 from Spikes.

Why do you have to have one?

From my sniper hide