WTF??? Anyone else's CMMG conversion have terrible accuracy???

T

Tikka223

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So on my last two range outings I've noticed that my AR + CMMG conversion was spraying bullets all over the place whereas it use to be quite accurate. Even the sound of the ammo when it fired seemed bizarre. At first I assumed it was an ammo issue but the ammo works just fine in my P226 classic. Today I inspected the end of the conversion kit that slides into the chamber of the barrel and it looks a bit jagged.

Pics up later. Anyone else have this issue???

If it is in fact missing bits of steel is my barrel going to be damaged?
 
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what weight of 22s are you shooting? really light ones might not get stabilized in the barrel..depending on the twist rate of your barrel ofc
 
realistically .22 is meant to be stabilized in a 1/12 or even a 1/14 barrel..... your not doing yourself any favours shooting it out of a 1/7 twist barrel and expecting match grade accuracy. that why a nice dedicated .22 upper is always nice to have.
 
When I say poor accuracy, I mean dismal accuracy. I was getting a 1' group at maybe 10m.

I took my AR apart tonight and what I initially thought was physical damage to the CMMG kit was actually a ridiculously thick layer of lead that's build up on it. I'm trying to clean the lead out of that mini barrel at the end and I'm not having much so. I'm now starting to wonder if CMMG parkerized the interior of the "mini barrel / chamber" and the finish is now coming off.

Can anyone recommend a good product to clean heavy lead fouling?

I'm currently using Hoppes # 9 and Hoppes MPro7 along with a brass brush.
 
The ammo I'm using is CCI AR Tactical that advertises 40gr copper plated bullets at 1200fps. So far it is by far the most reliable .22lr I've used in my semis until these current accuracy issues.
 
Tikka223 said:
When I say poor accuracy, I mean dismal accuracy. I was getting a 1' group at maybe 10m.

I took my AR apart tonight and what I initially thought was physical damage to the CMMG kit was actually a ridiculously thick layer of lead that's build up on it.
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Once you get all the lead out of it switch to a copper jacketed round.
My CMMG kit only functioned well when it was really clean. I got tired of it and sold it.
One of these days I'll put together a dedicated 22LR upper with a 12 twist barrel.
Watch that all that lead that is getting left behind doesn't plug off your gas port. If you switch back to 223 and it isn't cycling properly you'll know where to look for the problem.

Good luck
 
TinkerBell said:
realistically .22 is meant to be stabilized in a 1/12 or even a 1/14 barrel..... your not doing yourself any favours shooting it out of a 1/7 twist barrel and expecting match grade accuracy. that why a nice dedicated .22 upper is always nice to have.
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This.
 
The CCI ammo I'm using at the moment is jacketed. I'm going to try and give things a very thorough clean and hope for the best. Right now the problem is that it looks like I've recoated everything in a thin layer of lead. Lead is shiny as well so it's pretty hard to tell what's clean metal and what smoothly polished lead.
 
How many rounds are through your AR barrel ? My dedicated upper has been very reliable.. I'm at 1000 rounds and I cannot miss a 6'' plate at 25 meters. Gonna try further out next time.

 
That's the exact ammo that I've been using. As for round count, I'd say probably in the area of 2000 .22lr rounds and maybe 100 .223/5.56. My local range (FRSA) has recently added several steel targets and the rules state they are only for pistol,calibers. When I hit the range with my P226 I run .22lr in both the P226 and my AR. 30$ gets me several hours of shooting with good ol rimfire. Typically I end the range session with some .223 to blast the lead out of the gas system.
 
Tikka223 said:
That's the exact ammo that I've been using. As for round count, I'd say probably in the area of 2000 .22lr rounds and maybe 100 .223/5.56. My local range (FRSA) has recently added several steel targets and the rules state they are only for pistol,calibers. When I hit the range with my P226 I run .22lr in both the P226 and my AR. 30$ gets me several hours of shooting with good ol rimfire. Typically I end the range session with some .223 to blast the lead out of the gas system.
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Barrel is clean? I suspect lead deposits are all over the rifling.

bollox said:
Is there such a .22lr round? I've never seen any.
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Oodles of them, yes.
 
Try chucking a .223 chamber brush into your electric drill and "buzz" the chamber and extension of the adapter. Do so until the parts get warm to hot. This procedure is often recommended on the .22 forums. The brass brush won't remove metal but will get the lead after soaking and will burnish the internal surfaces to reduce leading.

BTW, I'm running the Alpha stainless model and use cheap washed ammo when I can get what I want which in Canada is the fed HP. My accuracy with a clean rig is excellent.
 
Pics finally up ...

I think the problem was a huge amount of build up lead, so much so that I think I've ruined a brush. I guess my biggest worry now is now much lead is in my barrel. Funny though, my 10-22 has thousands of rounds through it and I can't remember the last time I cleaned it. I wonder if it has the same issue.

This is when I thought there was physical damage to the CMMG.

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This is after removing a lot of lead from the mouth of the CMMG.

DSC_1000_zps16073eb1.jpg


DSC_1002_zps68677e71.jpg
 
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