View Full Version : First hand knowledge of issues with 5.56 in AR-15 after use of drop in .22 kits.
What I am looking for is first hand knowledge of issues related to reliability of firing 5.56 ammo after using a drop-in .22 conversion. So either an issue you have had or personally witnessed.
I am looking at .22 options for the AR-15 . Drop-in kit or .22 upper? There is no doubt that the .22 upper will be more accurate. But it seems that the .22 drop in kits are accurate enough for what I want to do with them.
I have heard of issues with reliability but that seems more toward ammo than anything else.
I have read about fouling up the gas tube, but so far have no heard any accounts of it actually happening to anyone personally.
Cleaning issues I am not concern about. My only concern us causing permanent damage to the rifle.
I ran 200 rounds of 22 ammo through a cmmg conversion with one problem. That was a failure of the primer to off. The key to me is running 1) high velocity ammo and 2) full brass jacketed rounds.
That isn't as cheap as cheaper lead low velocity 22 ammo. But it is much cleaner and cycles the conversion kit more reliably.
Tomahawk_Ghost
06-15-12, 15:07
I'll echo what the above poster said. I run a CMMG conversion kit. No problems, fun way to introduce people to the AR or just for fun running and gunning. I've had the best results with CCI mini-mags.
I always fire at least 1 mag of 5.56 after running the .22 conversion. That will clean out your gas system.
Find ManBearPig!
06-15-12, 15:13
Here is my experience:
I put a CMMG conversion bolt into my BCM 16 mid length. Fired off about 700 rounds (EDIT: Not all at once, over the course of a few range trips) or so, with my only issues being primers failing to go off. Afterwords, I put my 5.56 BCM bolt back into the gun. At first, it would not cycle, but I fired off about 10 rounds or so, which unclogged the gas tube and got the gun back to 100% reliability.
The kit pays for itself very fast and allows you to use the AR at certain indoor ranges that do not allow rifle calibers. I heard some ranges even have limits on pistol calibers too, apparently, but I am 100% positive that any range in the world will let you fire of a .22 LR firearm in it.
Also, I emailed BCM about barrel damage. They said I can shoot all the .22 I want, I just need to clean the barrel a little bit more.
The kit has surprised me with its reliability. I clean it off every other range trip and use Slip 2000 to lube it. Overall, I think it was worth the cost. It's all ready payed for itself in terms of ammo cost.
The conversion units are usually okay as far as it goes, An AR twist rate is not designed for .22 LR. As far as reliability, does it really matter. It is a .22. And they usually do have some reliability issues. But, I personally would not run one on a fighting carbine that you might need to depend on. Mostly due to fouling and leading issues. Mainly in the gas tube. Lead shavings can ( and do) get into the gas system.
I would, however, run a conversion on a dedicated AR. Maybe this would be a justification for a lower tier weapon. Or just get a .22 such as a S&W MP 15-22. But to each his own.
I have both the CMMG kit and a few M261 kits along with a dedicated CLE upper. I am thinking real hard about getting a dedicated upper for my work gun. While the conversions work great as long as they are cleaned a dedicated unit works a lot better since the 22 lr bore is alittle smaller and the twist rate is not as tight.
Dan
wetidlerjr
06-15-12, 16:30
I had no operational issues with a CMMG conversion when used with a BM lower. I did have an issue with a dedicated upper that wouldn't cycle with the BM lower until I changed the hammer to one without a notch.
I use Federal "Brown Box" 22LR with both the conversion and dedicated upper.
Yesterday i purchased a cmmg kit for my LMT, i've put just under 300 rounds of Federal 38 gr copper plated hp mfg# 712 and its been awesome, i honestly giggled when i pulled the trigger for the first time. With my BC 2.0 it is a little bit louder than i was expecting but there is no recoil whatsoever.
My only complaint is the magazine fitting is a pain.
Hot Holster
06-15-12, 17:58
I have a CMMG stainless conversion kit and I have not had any problems. And like some of the others, I run a mag of .223 through the rifle after shooting .22's with the conversion.
The kit pays for itself very fast
I crunched the numbers a while back, and for an actual .22 upper and based on local retail for numbers to bounce off, it was like 2 1/2 bricks to pay itself off in savings by not shooting 5.56mm
The more common drop in BCG rig would be even less.
FWIW here is a cautionary tale. I posted this on 1/17/11:
"Went to cleaning the barrel of my M4gery today after putting 40 rds. of Federal American Eagle through it with the CMMG unit. I noticed a very distinct "loose spot" about 1/2" long in the area of the FSB, both with the brush and more particularly with the patch when pulling it in both directions there. Last week I noticed that after a similar session the brush was a very hard push but attributed it to a new brush and didn't think much more of it. Tonight it's obvious something is wrong.
The last time I fired centerfire rounds was about a month ago, and nothing odd there. Once in a while the bulk Federal ammo gives a slightly funny report, and if it does I stop and make sure the barrel is clear.
Just wondering if a centerfire bullet jacket got lodged at some point, or if a .22 LR squib did get by me doing drills. The CMMG unit does get cranky at times and becomes a distraction clearing it.
I hate to think that I have a bulge, but the way the patch feels, it's doing a really good imitation of just that. Continued solvent and brushing is making no difference. Can't see anything definite looking through the bore but a .22 doesn't let you see much.
Any ideas that might let me make a better diagnosis here? I'd feel better if I knew for sure. It would definitely be a first in a lot of years shooting for me."
Bear in mind that I cleaned the bore religiously after each shooting session, which was only about 40 rounds on the timer. When I had my gunsmith check the barrel out he confirmed that it was in fact bulged. I sprung for the tools and changed out the old barrel for a new lightweight one, changed out the old bolt due to round count, and checked the headspace. It lightened up the carbine a little and the new barrel definitely shoots better. I attempted to section out the bulged portion of the barrel to actually see what it looked like but the steel was too tough to do it right. So while I will never know just what happened here or why, whatever it was, it happened as a result of using the CMMG kit.
Lesson learned; needless to say I discontinued using the CMMG unit and it went down the road. I still like the idea of a .22 subcaliber practice gun, and a few months later bought a S&W 15-22 which has been a joy to use. I only wish I had bought the 15-22 in the first place instead of "going cheap".
Take it for what it's worth.
I have a CMMG conversion kit that I've put most of a 525 round carton through. It's been reliable and accurate enough through m 1/8 barrel to hit empty shotgun shells and break clay pigeons. Standard brass ammo has been run through it after using the 22 LR with no problems. I did have one steel cased Herter's stick in the chamber, but that was after swapping between the conversion kit & shooting the Herter's.
I like being able to use the same carbine with the same optics. It's also a whole bunch of fun and the looks I get from my friends when they first shoot it is priceless
I've heard 22s leave deposits in the rifling and you have to clean the crap out it to get them out. Is that true?
4DAIVI PAI2K5
06-16-12, 07:39
I shot bricks and bricks and bricks of cheap CCI blazer in my kit with out issue. I have since moved to a dedicated upper, but thats just because I had the spare cash.
My 11.5" AR has upwards of 20k rounds of .22lr through it using a SS CMMG Kit with no issues. I always fire a few rounds of .223 through it to clean things out which can be interesting depending on how much rimfire I just put through it. There's typically a few nice clouds of smoke as all the crud and such is blown out leaving things fairly clean.
Rimfire ammo is fairly soft lead so whatever deposits are left in the barrel will pretty much be blown out with a few rounds of jacketed rifle ammo. 50k+ psi blowing through the gas tube does a pretty good job of keeping it clean as well ;)
The rimfire ammo will leave some lead crud and buildup on my BC 1.0, however that too gets blown out when rifle pressure ammo follows up a shooting session.
Sent from my DROIDX using Tapatalk 2
I ran 200 rounds of 22 ammo through a cmmg conversion with one problem. That was a failure of the primer to off. The key to me is running 1) high velocity ammo and 2) full brass jacketed rounds.
That isn't as cheap as cheaper lead low velocity 22 ammo. But it is much cleaner and cycles the conversion kit more reliably.
This is the same excact experience I've had with my CMMG .22lr AR-15 conversion kit. As long as I use high velocity FMJ ammo it works great.
CMMG warns the conversion kit only works with high velocity ammo. The stuff I've been using is copper plated
I had a squib load using the conversion bolt and didn't notice it until I got home and cleaned it. It slightly bulged my barrel just a couple inches past the chamber. I now have a dedicated .22 upper on the way.
Just pay attention to the sound of each shot if you can, I was at a crowded range with ear plugs in and i didn't even notice.
After pulling out a .22 kit from my rifles I couldn't fire 5.56 in it until after I ran a chamber brush through it first.
Only issues I've personally seen(besides 22 conversion kits just not running) were issues where someone went from a 22 kit back to 5.56 without cleaning the rifle. I've seen friends have issues but they were fixed by cleaning the chamber/barrel.
+1 for conv. kit..I however rock the Ceiner kit (with the metal clip):).
Was thinking about getting the conversion but got the dedicated cmmg upper 20" and have been very happy so far.
Shot over 1,000 rds and not a single issue. I would recommend getting the stainless steel upgrade. It makes cleaning and lubing very easy.
hotrodder636
06-17-12, 12:27
I am not saying that a dedicated .22 upper isn't worth it and won't pay for itself fast, but I chose the conversion kit route. I purchased the CMMG stainless steel kit 8 months ago and have put around 600 rounds down range. Biggest issue I have are jams (AR style stove-pipe). Can't tell if it's a feeding or ejecting issue however, as I just clear the malfunction and move on. Maybe next time I will investigate a bit more. I do however use lead rounds not the copper jacketed. I do shoot CCI mini-mag through occasionally and it runs just fine. I usually clean out as said before with some .223 or 5.56 at the end of a session and a heavier cleaning regiment afterwards as compared to only shooting 5.56/.223, YMMV.
davestarbuck
06-17-12, 20:29
I've run thousands of rounds through various uppers using my Ciener kit, most recently 800 + rounds through my BCM EAG upper, which still shot a 3 inch 100 yard group using Wolf 75 gr directly after running the .22 through, using an Aimpoint H1.
I use the same cleaning schedule on my barrels, which is never :)
I've never had a gas tube block up.
I'll wipe out the upper and lower a bit more, and throw more lube on, that's it.
My original BCM 16" carbine upper (one of the first $399 ones) is still going strong after 12,000 rounds of various .223 and probably close to the same with .22 lr. I'm confident it will serve it's new owner well (hopefully I can get him into a class soon).
My experience is that shooting .22 lr won't effect anything.
CMMG carries various kits (levels) for the .22lr conversion. Which kit provided the best results? Any recommendations on a purchase?
Thanks
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