I'm new and this is my first post, so bear with me. I had a president elect moment and purchased a CMMG carbine at a local dealer. I put an Eotech 557 on the top. My first shooting experience was awful. First, I couldn't find the target at 25 yards. I had to get to 10 yards to discover I was at least 15" off center. Next, the rifle started jamming after a couple of shots. The magazine wasn't feeding the ammo in to the barrel, and the bolt was jamming open. I finally got the rifle on target (still jamming), but couldn't hold a good group. Next, I noticed the scope was loose; not a good day for the first shoot.

I took the rifle back to my dealer and told him my problem with the jamming. He asked "Did you lube the bolt?". Well, of course not. I thought the rifle was ready. Anyway, he moved the scope back some on the flat rail so the scope was seated properly, and lubed the bolt. I certainly hope this thing shoots the next time out.

Anyway, has anyone had any experience with the CMMG piston rifle? Any advice to a newbie AR-15 owner?

Thanks,

Diverace.

I don't know what a CMMG piston rifle is... I went to their site and saw where they are selling piston conversions. It looks somewhat similar to the Addax/PWS system but I think it's an Adams Piston kit. Most AR systems, including pistons require a decent amount of lube. I'll get smacked for saying this but the Addax GPU upper I'm evaluating hasn't seen the first drop of lube.

If you are using the large screw to attach the EOTech to your upper, get it hand tight with a quarter... then turn it about 1/8th more with a tool. I usually put a quarter in a pair of pliers. If it's off by 16 inches at 10 yards you're going to need to turn the dials a couple of 180's or even 360's. Start by a half turn and see where it hits. Continue until centered and move back and repeat the process. Get it centered horizontally and about two inches low at 25. You'll be on at 50 and 200 and have an easier time hitting with it there opposed to 25.

Lube it up good and fire it. It probably needs to be "broken in". I mean the system, not the barrel. I'm having an ADD fit so ....


TS

it might be a good idea to go back to the dealer before the next range trip and ask him to bore sight it for you, that way you will not waste much more ammo trying to dial it in.

and good luck!

I have a CMMG Piston Carbine, since I test many of the different systems on the market.

I had a problem getting the bolt to unlock properly when charging the rifle, and the piston system is not worth the price they are asking for it.

I also purchased their piston kit, and the gas block is 2 pieces and there is no gas / pressure chamber, so it is not really self regulating.

To me, the CMMG Piston Carbine/AR kicks like a mule compared to our Addax Carbine GPU's.

I fixed the bolt problem by swaping it out with a bolt that fit better.

The CMMG kit is built for them by Kodiak Rifleworks, and it is much more similar in design to the Adams Arms system.

The PWS piston systems we use on our Addax GPU's are very different from these, you could say our systems are much more advanced in terms of design and functionality.

I would just give it a small shot of WD40 around the bolt and carrier, you do not have to soak it or anything like that.

Different animal I know but I had the same problem with My Bushmaster first time out BUT I was using steel Wolf ammo(figured that was the issue), jam almost every round and not feed. Went home and cleaned/lubed it (per advise of the forum members!) and bought some brass, shoots like dream!

This post has been edited by NOSJNKY: November 29th 2008 8:41 PM

When I mentioned it looked like the Addax system, I was referring to the piston tube mostly. They look similar when you compare the CMMG website image and pages eight and nine in the Addax manual.



Will Breakfree work? I have a gallon or so of it.



TS

Sure, but that gallon is going to last you a lifetime with our GPU

I'm looking forward to that.


TS

Hey All.

I just bought that CMMG conversion kit from a friend who decided he would rather buy an AK instead of an AR. I dont have an upper
to put it on, maybe if i can find a dealer who hid some away. Hehehe, Well anyway it looks solid, though it dosent have a gas ajustment,
just an allen head bolt you thread in. It has a carrier like the Bushmaster / ARES with a machined tapet on top of the carrier. Who knows but
I am not too sure about it. But figured what the hell he was asking half of what he paid so what the hey.
If I ever get an upper to throw it on I'll let ya know how it works. Or I just might sell it off, one never knows.

Happy Holidays All