CMMG .22 LR Conversion

[Chemistry Guy]

I just got the cmmg .22 LR conversion for my 16" M4 configuration AR. A guy at the range told me that I should always shoot some 5.56 when I am finished practicing with the .22 to clean out the gas system. If I don't, he said, a gunsmith will be needed eventually to clean them out for me.

Is there any truth to what he is saying? Is he talking about powder residue condensed in the gas tube or lead from unjacketed bullets blocking the gas port? In either of these cases, I do not see why a simple pipe cleaner could not take care of the problem. I also do not see how shooting 5.56 could help.

Am I missing something or is this a blatant case of misinformation?

 

[ny32182]

I haven't had mine long enough to know if it is "really true" or not, but it makes some sense to me.

The .22 is very dirty. It also probably isn't generating enough pressure to clear the gas tube. It wouldn't surprise me if prolonged .22 with no .223 would get a lot of crap accumulated in the gas tube. Whether this could eventually be enough to interfere with .223 operation I don't know, but it is easy to put a couple rounds of .223 through to blow out the gas tube at the end of a session shooting in the .22lr, so, to me right now it is just kind of one of those "why not do it" kind of things.

 

[cougar1717]

A guy at the range told me...

Always be polite, but consider the source when listening to those who wish to impart knowledge at the gun shop, range, skeet field, or THR for that matter.

Having said that, I think there is a little embellishment going on with his advice. 22LR does not use the best powder by any means, and it is likely that some of this powder would get caught in the gas tube, but needing a gunsmith to clean out the gas tube seems a little far fetched. The person may have been trying to warn you about possibly getting lead shavings from the 22LR bullets in the gas tube. One good method to clean out your gas tube is to make sure when you clean your gun to put a couple of drops of CLP down the gas tube and put the muzzle toward the ground. The CLP will coat the junk in the tube and the next time you fire it, it will "clean it" for you. If all else fails, use pipecleaners.

 

[ny32182]

I don't put anything in my gas tubes. ~20k psi at the gas port from a .223 round is going to clean it out quicker than anything you can shove through it.

If I ever somehow got a tube plugged, I would just replace it... all you really need for this is a new tube (less than 15 bucks), pin, punch, and mallet. Shouldn't really require a gunsmith.

 

[gb0399]

Just my opinion

I think that there might be a half truth somewhere in there. I'm not an expert on 22 conversions, but as I understand their function, the gas tube serves no purpose with the conversion. I believe its a blowback operation. But the gas tube is still open so carbon could travel up the gas tube and stay there. So I would say that it would be possible to get a build-up. However, I think that’s where it ends. I would say that as soon as you fired the first 5.56 the problem would be gone and that you shouldn’t even worry about it.

 

[desidog]

I'd say just the opposite; I would not fire .223 after .22lr through my AR.

If the .22lr is depositing a bunch of junk in the gas tube, that same stuff is in the barrel. With soft lead bullets junk in the barrel is no big deal, but with a copper jacket traveling 2x or 3x the speed of the .22lr, I imagine that the junk would be ground into the barrel, creating small pits and scratches...which over time might be large pits and scratches.

Worst case scenario is that the dormant .22lr junk gets blown down the gas tube back into the action on the first .223 shot; which will happen anyways....which is why you clean your guns after shooting.

Much more important is to clean out the junk that collects around the neck of the converter in the .223 chamber, before chambering a .223 and grinding that stuff in there right on the throat....over time that'll definitely hurt your barrel.

 

[Jeremy2171]

per the military TM you are to fire 3 or 10 (cant remember) 5.56 ball rounds after using the .22 conversion kit....to clean out any fouling "or" as needed during training to improve reliability.

 

[gb0399]

Links to the army TM, and the CMMG manual. Both say to fire rounds to clean gas tube.

ARMY TM
http://www.txmarks.org/cdfiles/Individual Weapons/TM M-16 22LR Adapter.pdf

CMMG MANUAL
http://www.cmmginc.com//Downloadable_PDF/CMMG_22-ARC/CMMG_22-ARC_Instructions.pdf