CMMG Mk9LE OR 9mm Who owns one?

[Munny$hot]

I was seeing about 4-5 MOA at 50 and 100 yards (federal AE 9MM) with my CMMG. Not complaining, it was a fine rifle - just my observations.

4-5 moa sounds about average for a 16" build @ 100.

[iMigraine]

Doing some internet research, I found out that Double Diamond Law Enforcement Supply is no longer. Apparently the company ran into financial troubles and some customers have been left without their orders and money too. Bummer, they seem to have made good AR 9mm lowers too.

http://www.m4carbine.net/showthread.php?124406-DDLES-Leaving-customers-out-to-dry

http://sigforum.com/eve/forums/a/tpc/f/630601935/m/1640078853

[BigBamBoo]

Old news.....but the financial backers to DDLES have taken over and are now called Quarter Circle 10 and have been selling the Glock lowers and Colt pattern lowers.

Website here: http://www.qcircle10.com/

I have spoken to Russ (one of the main partners of QC10) and he seems like a good businessman. I think they will be around for awhile. He refuses to sell inventory they do not have on hand and no "pre-ordering". That is wha got DDLES into trouble....selling lowers that were not even made.

[rmatt]

I have a CMMG 9mm ar and love it. The gun has worked great and is the most popular gun when letting family or new shooters have a go.

Having just built my own 9mm ar off of a 80% I can attest to the simple joy of having a dedicated 9mm lower like the CMMG. If you at all want one, I say get it!

Though, I would also say buy 2 Colt 9mm AR specific bolt catches. If a part is going to break on the rifle, it will probably be this.

I have only used various metal mags and all of them have worked and all of them have held the bolt open on the last shot.

[iMigraine]

I have a CMMG 9mm ar and love it. The gun has worked great and is the most popular gun when letting family or new shooters have a go.

Having just built my own 9mm ar off of a 80% I can attest to the simple joy of having a dedicated 9mm lower like the CMMG. If you at all want one, I say get it!

Though, I would also say buy 2 Colt 9mm AR specific bolt catches. If a part is going to break on the rifle, it will probably be this.

I have only used various metal mags and all of them have worked and all of them have held the bolt open on the last shot.

I read that is a common problem with some AR 9mm's. This thread http://www.calguns.net/calgunforum/s...d.php?t=673622 might have a solution for that. Someone suggested http://heavybuffers.com/ar15carbine.html as a fix. Did yours break? If so what type of ammo were you using? Light, medium, or hot loads? I assume your using a CMMG 9mm upper too?

[BigBamBoo]

Bolt catch breakage is generally caused by to much rearward travel. The bolt gathers momentum as it starts back towards the chamber. It then slams into the bolt catch. Do this enough times and the cast bolt catch breaks.

Heavy Buffers makes their Q-Buffer which is longer (and heavier) then a standard 9mm buffer. It limits the rearward travel and helps keep the bolt catch from being beat up as badly.

It is best to use a machined bolt catch made of chromoly and not the mil-spec cast bolt catch that comes in a lower parts catch.

The ammo really has no effect on the bolt catch breakage. But...again, you need to use a heavy(er) buffer to help keep the bolt closed longer and let the cartridge complete its ignition/powder burn cycle completely before it starts it's cycle.
If you use a too light buffer, you can get out of battery firing...a bad thing. If your lucky you will just have bulged cases. If your not lucky you can have the cartridge explode inside the gun causing all sorts of excitement.

So the point is do your homework and use the CORRECT parts....there is no way to really build a "cheap" pistol caliber AR if you want to do it right. I know, I know...this is CalGuns and most people want to do it on the cheap.

.

[rmatt]

i have a spikes tactical 9mm specific heavy buffer. in another gun i have a rra 9mm buffer. yep, finding the right buffer, spring combo and possibly spacer was key to getting them to run right.

i've broken two bolt catches in 4 years. shooting probably 1k of rounds a year through them.

i shoot my 130pf pistol competition's round through them. so not a hot load at all.

my dedicated 9mm ar rifle is a cmmg lower that has a rra 9mm carbine upper. my 9mm pistol has a 80% lower with a mag block. it's upper is from a small shop in la habra, vytamen c.

i use these primarily to shoot steel matches with in open or tactical. sometimes to great success. and compared to the 22lr AR's i can knock down all the plates.

[iMigraine]

i have a spikes tactical 9mm specific heavy buffer. in another gun i have a rra 9mm buffer. yep, finding the right buffer, spring combo and possibly spacer was key to getting them to run right.

i've broken two bolt catches in 4 years. shooting probably 1k of rounds a year through them.

i shoot my 130pf pistol competition's round through them. so not a hot load at all.

my dedicated 9mm ar rifle is a cmmg lower that has a rra 9mm carbine upper. my 9mm pistol has a 80% lower with a mag block. it's upper is from a small shop in la habra, vytamen c.

i use these primarily to shoot steel matches with in open or tactical. sometimes to great success. and compared to the 22lr AR's i can knock down all the plates.

Nice looking rifle RMatt. Does the River Rock Arms upper have a ramp for the barrel? Or is that part of the lower on the CMMG? What kind of MOA are you getting with yours?

[Munny$hot]

CMMG 9mm bolt hold open catch are longer than a standard ar15 bolt catch so if your going to look for a machined part keep that in mind. Also a standard buffer will work but you have to limit the travel of the bolt to @ 1/4" past the extractor. Spikes tactical makes a spacer, or you can use 8-12 quarters or spacers that will fit in the buffer tube depending on your tube.

[Full Clip]

I rebuilt a CMMG 9mm upper with a Colt receiver and use a Hahn mag block. Spike's brake. Love shooting it and it eats everything I feed it...

[iMigraine]

CMMG 9mm bolt hold open catch are longer than a standard ar15 bolt catch so if your going to look for a machined part keep that in mind. Also a standard buffer will work but you have to limit the travel of the bolt to @ 1/4" past the extractor. Spikes tactical makes a spacer, or you can use 8-12 quarters or spacers that will fit in the buffer tube depending on your tube.

So if I understand this correctly, I will need Spike's Tactical ST-9BS or Heavy Buffer's 9mm Q Buffer or equivalent part in any AR 9mm upper I use to avoid broken bolt catches?

Kind of a bummer that CMMG, River Rock Arms, and others don't give you a proper buffer to begin with.