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CMMG .22 conversion kit work...

Started by ThaiFighter, February 02, 2010, 02:22:18 PM

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ThaiFighter

The .22 kits are pretty notorious for having feed/bolt closure issues, especially when new.

I have had this problem twice now. The first time was when I first bought the kit. Well the directions said there'd be a 500 rd "shoot in", so I assumed it needed to wear in. So, I made do and had to manually push the bolt closed with my thumb quite often. It was ANNOYING as hell.

I was out shooting with it about two weeks ago and when I went to pull out the kit, the back plate weld had snapped.

Son of a...    :wb:

I emailed CMMG, and their customer service was excellent. They emailed me the next day to inform me that a new frame was being ups'd to me. I get the new frame and install it, put it in the rifle and cycle the charging handle...

Son of a...   

Bolt barely moves forward...    :wb:

I can't even push it closed. I was about to throw the whole damned thing through a window, but I've got about 200 bucks in this kit.

It's GOING to WORK dammit!   >:(

I dremeled off all the coating on all bearing surfaces and lubed it up (it's a stainless steel kit) to see if that coarse coating was the issue. It still hung up. SO I pulled the kit and reinserted it several times to see if I could see any wear spots that might indicate where it was hanging up and noticed that it required quite a bit of pressure to push it in that last inch. I thought this was due to the chamber or gas tube seating tight.but just to be sure, I whipped out my micrometer and check the inside clearance of the action vs the outside width of the new frame...

moral of the story is that it was simply too tight of a fit. when the kit was fully seated in the rifle, it was compressing the side of the frame rails causing the bolt to bind. It also turned out that the frame with the chamber installed was .02" wider at the chamber end than the rest of the frame.

I relieved that .02 width off of the front of the frame and it now cycles better than it ever has. It still fits nicely in the rifle with just the faintest hint of resistance when I push it in the final inch. I took a polishing wheel and some jewlers rouge to the feed ramp and I can charge several different types of ammo and the bolt closes completely. 

If the rain lets up, I'll be taking it for a test drive this afternoon. If anyone else has this kit and has an issue. I hope this will help resolve it. 
"Reasonable people adapt themselves to the world. Unreasonable people attempt to adapt the world to themselves. All progress, therefore, depends on unreasonable people."

-GBS

Proud to be funding TG and BF's retirement account... ;)

Garand69

That's a bummer you have had such issues. My CMMG conversion has work well, though accuracy isvery finicky with ammo choice, other than that it is good to go.
Garand69

42

WSMR 03-10 ...SAPPER STEEL!!!!

"Don't tell people how to do things, tell them what to do and let them surprise you with their results." - General George S. Patton Jr

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henschman

I remember my buddy had to re-weld those spots on the back of the frame on his when they broke.  Other than that, its had no problems.  Those welds must be a weak link in their design.
"Of liberty I would say that, in the whole plenitude of its extent, it is unobstructed action according to our will. But rightful liberty is unobstructed action according to our will within limits drawn around us by the equal rights of others. I do not add 'within the limits of the law,' because law is often but the tyrant's will, and always so when it violates the right of an individual."
-- Thomas Jefferson to Isaac H. Tiffany, 1819

Mudcat

No problems out of mine except for the so so accuracy.
"A free people ought not only to be armed and disciplined but they should have sufficient arms and ammunition to maintain a status of independence from any who might attempt to abuse them, which would include their own government."
--George Washington

Long Rifle

I've got a Tac Solutions complete upper. I know it's not the same rig you have but when I got mine it malfed every 3 or 4th round. I was able to persevere and get almost 200 rounds through it and the malfs went to every 5 or 6. After reading some recommendations on Gunkings (where I got the upper) on replacing the hammer on my lower with a non-notched one the malfs completely stopped. Don't know if this will help you but thought I'd throw it out there.

Long Rifle

LKB3rd

I shot one of these that a guy at the club had, and I shot 3 shots @25 yards, 2 were within an inch or so and one was 3-4 inches to the right.  It had an aimpoint, and I might have jerked that one, but not that much for sure.  Is this typical?

ThaiFighter

pleased to report, the fix worked.  Very few malfs yesterday.   accuracy was still not what I wanted, but at least it's working.   I will try to find a brand it likes.  anyone got recommendations? 
"Reasonable people adapt themselves to the world. Unreasonable people attempt to adapt the world to themselves. All progress, therefore, depends on unreasonable people."

-GBS

Proud to be funding TG and BF's retirement account... ;)

Old Dog

I smear lapping compound on the rails and work that bolt back and forth by hand several ( :)) times.  Enough till the finish is gone and I figure its got to be pretty smooth, then I clean it, lube it and see how smooth it feels.  I repeat the lapping if I feel I need to, then clean again and relube.

If your bolt almost goes shut, but not quite, check to see if the bolt is rubbing the right side feed lip on your black dog or other aftermarket plastic magazine.  The bottom of the bolt is different side to side and sometimes one will rub that right side magazine feed lip.  Look at the lip to see.  If so, use a pocket knife to lightly scrape some plastic off of it.  Make a few scrapes and retry the magazine to see if the bolt will go shut.  Repet till it works.  Mine's been running great with Rem. Golden Bullets or the Federal bulkpack.

Good luck with yours.
"The rifle itself has no moral stature, since it has no will of its own. Naturally, it may be used by evil men for evil purposes, but there are more good men than evil, and while the latter cannot be persuaded to the path of righteousness by propaganda, they can certainly be corrected by good men with rifles."

—Jeff Cooper, The Art of the Rifle

ItsanSKS

TF, I think it would help if you posted pictures of exactly what you are talking about; I know that listening to you describe the work you did, didn't really 'click', and then when I saw what work you had done, I was quite impressed.

"Those who would trade an ounce of liberty for an ounce of safety deserve neither."

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