Problems with my new CMMG .22LR conversion kit - help!

[Pro2AInPA]

I went to the range to try out my .22LR conversion kit today. Every mag I fired, at least one round would fail to extract. It would just be stuck in the chamber, so I would have to remove the mag and rack the charging handle five or six times until the extractor finally pulled the spent cartridge out. I hope someone knows why this might be happening. The only thing I can think of is I might have overlubed it. . . since the instructions don't say where to put lube, I just slathered the whole damn thing down. Thanks for any help!!!

[supersix4]

I have the same kit and I did not lube the INSIDE of the chamber, all I lubed were the rails and spring. clean it up and dry it off with carb cleaner or the like and just lube the rails and spring, then give her a go. mine has run quite well since I have had it.

[austinN4]

I have the same kit and I did not lube the INSIDE of the chamber, all I lubed were the rails and spring. clean it up and dry it off with carb cleaner or the like and just lube the rails and spring, then give her a go. mine has run quite well since I have had it.

+1
Clean the packing gunk off the new kit. Lube the contact areas of the bolt and rail so the bolt slides freely. I use a light coat of Brian Enos' Slide glide for this area. I put a very light coat of gun oil everywhere else and it runs great.

Also, what ammo were you using. Mine won't run worth a darn with Remington Goldens as they are too waxy to feed and extract reliably. I shoot nothing but cheap Federal #750 bulk pack, which is clean and dry, and mine runs great. With the Federals I have not had one FTFeed or FTExtract in 2,300 rounds so far.

But if it is not lube or ammo, you might need to replace the extractor. Se this thread for some great info on what some do to tweek their kits: https://www.m4carbine.net/showthread.php?t=21306

[lindertw]

in addition to cleaning & lubing as mentioned above, I found that if I only loaded the mags with 20 rounds (vice to capacity) when it was new then that greatly reduced FTF/FTE's. For your next range visit or two:

clean/lube it as mentioned above
use Federal bulk pack ammo, if available
load no more than 20 rounds in the mags

After you have 500-750 rounds down range things should settle in. This is the point where I'd watch the chamber adapter for cracks. If the kit is unusually difficult to remove from your upper, that's a clue your chamber adapter is toast

If after 500-750 rounds you're still having problems I'd look at the firing pin (ensure it moves freely in the FP channel), and the extractor. BDM makes an excellent replacement piece.

Hope this helps (and PM sent)

[MX5]

I've been running several converted uppers & a few dedicated .22 LR ARs for quite some time. While I have my own methods for prepping a conversion kit for use, here's one that anybody can do in a very short time.

1. Take your new conversion kit & clean all oil/grease from it. I use lacquer thinner, but you can use any good solvent that will dissolve oil/grease with little or no residue left behind.

2. Let the solvent evaporate, then hand cycle the moving parts 500 times.

3. Clean again, dry & lightly lube the wear surfaces.

4. Take to range & fire 500 rds. CCI Mini Mags.

If you feel you have the skills needed (minimal), disassemble the conversion, clean & lightly polish the wear surfaces with 600 grit, then 1000 grit wet-or-dry paper, prior to add'l cleaning, lubing & testing.

My methods are more involved & change the dimensions of some parts, but the above will generally work very well in most conversions.

CCI Mini Mags tend to work the best overall, in my opinion. However, once I'm assured it's working to my satisfaction, then I'll try various other brands to see what works well & what doesn't in that particular one. .22s are very finicky about ammo & each one is unique unto itself.

YMMV - Enjoy!

[Hellbilly]

I have recently purchased one of these CMMG .22 conversions. So far I have only tried it in a 16" 1x9 twist Bushmaster.

Functioning has been very good but accuracy isn`t much to write home about. Winchester Wildcat and Remington Cyclones are a waste of time. CCI Stingers are better but still not good enough to be considered worthwhile for practice.

CCI mini mags are next if I can find any in stock to purchase.

[CryingWolf]

Also, what ammo were you using. Mine won't run worth a darn with Remington Goldens as they are too waxy to feed and extract reliably. I shoot nothing but cheap Federal #750 bulk pack, which is clean and dry, and mine runs great. With the Federals I have not had one FTFeed or FTExtract in 2,300 rounds so far.

+1

I lubed the crap out of mine. Light coat on the outside chamber but lubed the rails and spring along with the extractor really well. Felt a little rough. The only thing I have fired through mine is the Federal bulk pack. Probably 400+ rounds so far not one FTF or FTE

If you were to work mine back and forth now it rides like butter on a hot skillet.

[motoman]

i have a cmmg and had trouble with the unit getting stuck in the upper. it just fits tight. shoots ok if i keep it wet otherwise lot of hang ups.

[RVGP]

Ok, I have an UPDATE on several tips suggested within this thread I have tried.

First, as with all new guns, I start with the feed ramp and polish that sucker up. I noticed my feed ramp was cut kinda cock-eyed, more deeper cut on the right side (defect?) I used a dremel grinding tool to even this out and then polish. With the ramp left that alone, I think I would have had a FTF.

Second, when inserting the conversion unit, the last 3/4 to 1/2 inch would not go in with out serious pressure. Since some of the folks here has had problems getting the unit back out, I decided not to push it in too deep. When I pulled it back out, I noticed some scraping marks along the phosphate coating where it was catching. Using 1000 wet/dry sandpaper, I sanded the entire insert area and removed the phosphate coating. The unit is made of SS so rusting is a not concern. I applied a small amount of anti-seize lube (choke tube lube) to the insert and it fit like a glove. Removal was much easier. Anti-seize lube must be cleaned from .233 chamber prior to shooting .223 ammo again.

Third, with the 1000 grit again, I sanded the rails as I always do to a new gun. This is equivalent to shooting 500-1000 round break-in. All sliding rail parts, inside and out, get a drop of oil and then sanded. The phosphate coating CMMG uses is great on the parts that don't touch but when in contact they actually grip each other much like taking two pieces of sandpaper and rubbing together. Removing this 'tooth' from both parts, then lubed, will make it slicked than snot.

Fourth, after reading how others where having firing pin problems, I decided to remove mine and check it. Lo and behold, my FP would not fall straight through either and hung up. Following the advice of others here, I sanded the pin with 1000 grit, removing most of the phosphate coating, dropped it in again and BAM, slid right through, no hang up.

Now I am convinced the phosphate coating is causing most of people's problems with these units. A little sandpaper on the right areas and these puppies will be smoking.


The BDM Big Dog magazines also were causing some folks problems. One person suggested taking the magazine apart and sanding out the bumps, so I did. Along the way a figured out a few more tips to these mags. My mags were new and I could barely load 20 rounds, a thumb buster for sure.

After taking the mag apart (careful not to lose any of the 3 red plastic parts and 2 springs) and sanding the inside channels where the followers ride until almost smooth, I liberally spread powdered graphite in the channels with a Qtip. Looking at the red plastic follower I noticed mold marks and bit of plastic left on from where it squeezed out during manufacture. These were grabbing the inside of the mag when I was loading and making it bind up, sooo I sanded them off, too and applied graphite. I reassembled, and I'll be a monkey's uncle if I couldn't load all 26 rounds and without hardly any pressure. Worked like a charm! I even sanded the outside corners and side ends of the mag where it contacts the mag well insides for a smoother insertion.

Anyway, I hope this helps. The CMMG is an inexpensive way of shooting but like all higher volume companies, final finish is very subjective and may require addition fine tuning. Otherwise, if they did the fine tuning themselves, they would become a lower volume, higher quality but with a much higher price tag!

Rob
Freedom Firearms of Kentucky

[Celer]

I'm using a spike's kit with black dog mags. A 3 or so FTE rate per mag doesn't bother me, but lately I've been getting stovepipes where instead of the case sticking out, it's sticking upwards into the space between the bolt carrier and frame (?), vertically, keeping the round pinned due to spring tension until i remove the carrier completely from the upper and pull both sides apart.

Can't find fed bulk anywhere, but have used CCI minimags and Remington gold. Anyone else get this? Also, the tension on my BD mags is a little flaky, sometimes the spring/follower seem to get stuck and rounds will fall out just by tilting the mag...