CMMG .22 conversion and lead rounds vs copper

Discussion in 'Rimfire Central' started by Jayne, Oct 9, 2019 at 9:31 PM.

  1. Jayne

    Jayne Just here for the memes Charter Member Supporting Member

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    On another project we ended up trying two .22 conversions in an AR pistol, one from the 60s and a modern CMMG unit. Both worked in the test rig, and I went ahead and ordered a CMMG unit for myself. Picked it up from Primary Arms, they had a good deal and shipped it quick.

    No super break in or high round count, just popped it in my 'good' AR, tossed the rimfire can on and it ran perfectly well with CCI standard velocity ammo (of which I have a ton of).

    I'm curious to know if any of you have high round counts through one using lead ammo instead of the recommended copper bullets?
     
  2. JimP42

    JimP42 Mostly harmless Benefactor Charter Life Member

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    I have one from ~8 (?) years ago that has run perfectly for 10Ks of rounds, mostly Blazer (lead) and Minimags (copper plated). Shot 2 gun rimfire matches with my 3gun AR for years that way. It is one of the all-stainless ones.
    I don't see much difference. They are lots of fun, and great for training with your primary AR. BUT - make sure you shoot some 223 through it every so often to blast the crap out of the comp, gas tube, etc...
    I have shot a lot of 22, and it makes a mess. At least a few rounds of 223 occasionally will help keep it from building up. Don't shoot those first few rounds with anyone next to you on a firing line if you have a comp. The little lead bits that get expelled sideways by the 223 will draw blood.

    22LR in a 223 barrel is usually not terribly accurate. Fine for blasting steel up close but not for groups at any distance.

    To balance this, I have a second (newer) conversion that doesn't work nearly as well. It seems to have more slack when inserted and too much junk makes it way back around the chamber insert. This one has some brass bits in it. Anyway, when they work, they are great.

    An M&P 15-22 is pretty much the standard answer for a 22 AR at this point, but you must know that. If you want to train with a particular rifle and don't want to build a dedicated 22 duplicate upper of it, then the conversion can fill that need.
     
  3. NCLivingBrit

    NCLivingBrit Clueless Protoplasm

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    I had one that I put several thousand rounds of cheap lead ammo through with no issues other than it running so dirty it looked like I'd smeared axle grease in it.
     
  4. NKD

    NKD Senior Member Benefactor Kimberless Supporting Member

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    The biggest concern for plain lead is leading of the suppressor being used, if one is being used.

    Not sure how much cleaner the copper plated will be.
     
  5. rdinatal

    rdinatal Better late then never...

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    Back when I first took possession of a CAR I also bought a Ciner M16 22 conversion. There were no instructions to use any type of 22lr with it, they all worked. Except...

    When on FA you tend to heat up the barrel. After about 6-8 30 round mag dumps of 22 (fun) the accuracy went to heck. Seriously a +-5ft spread. Looking at the barrel it was 1/2 lead. Some joker said to run a couple of 5.56 in it. Glad I looked first as that would have killed a $1500 rifle plus multiple personal injuries. It took a couple of hours and 5 or so bore brushes to get it clean. Look first!

    After that I only used copper coated 22lr in the CAR. The leading was darn near non-existent (powder residue was still the same) but I always looked before switching back to 5.56. Still do, all the time, every time.

    Will you shoot enough to heat up the barrel to melt the projectile? In a SA not sure, but in a FA you definitely can. I shoot non-plated 22 in all my ARs and don't see abnormal leading but I always check.
     
    Last edited: Oct 10, 2019 at 10:59 AM