I put together an AR-22 upper with a CMMG 4.5 inch barrel.  When firing it the other day, the accuracy was horrible at 25 yards.  Is this to be expected?  I have heard some people got about 1 inch groups at 25 yds with the same barrel.

How big were your groups?  Did you try different ammunition?  My first CMMG .22 bbl appeared to have pretty bad accuracy but with a lot of testing, I found it to be quite accurate once warmed up.  When cold, the first 1-2 shots were pretty bad fliers.  They made it right, the next bbl is very accurate, less than 1" at 25 yards for 10 shots.

My first thought would be to try different ammo.

Sorry for the late reply.  Finally got to the range and try to group the gun.  I was using Federal Gold Match.  This from probably about 3-4 5 round groups fired using a Trijicon MRO at 25 yds on a sandbag.  I also shot at a metal plate at 5 round intervals, and at one point the rounds started grouping in the center, but went back to all over the place.  I'm going to try some CCI and see if that helps.

CMMG had a bad batch of barrels a couple years ago.  I think I read they had bad crowns.   I had Kurt from KKF build me an upper several years ago and it shot patterns not groups.  After a couple thousand rounds the barrel is now a very good shooter.  I can't remember if I was cleaning the barrel when it was new.  I've since learned it is not always necessary to clean rimfire barrels as the barrels season with use.   Once accuracy falls off clean the barrel unless you get caught in inclement weather and are concerned about corrosion.

I suggest you run at least a couple thousand rounds through the barrel.  If the accuracy doesn't improve I'd contact CMMG.

Shot the 22 again today with the Federal ammo and got the same results.  Very inaccurate.  Had some CCI subsonic ammo with me so decided to try it.  It seems like the Federal ammo is the culprit for the inaccuracy.



5 shot group with the Federal ammo at 25 yds.  One didn't even hit the paper.



5 shot group (bottom 5) at 25 yds. with the CCI subs.  A lot better groups.  Going to find some CCI Standard and see what kind of groups I can get.

Vascar is correct.
Some were shipped with no crown at all.

Dave N

Mine was one of them!
Sent the complete upper back, they paid shipping both ways.

I can now crown my own barrels.