I've tried this in both my Cerro upper and my ArmaLite upper, without the charging handle everything moves freely.

With the charging handle inserted the bolts on the conversion kits seizes up and won't move. It's a bear to remove at that point too.

Have 5.56 chamber (same problem with stripped upper anyway.)

Not using any weird/special charging handle. Just the cheapie that came with the rifle.

http://i.imgur.com/duCY9lj.jpg/img]

Any thoughts?

I brained it out. The shape of hte underside of the charging handle collides with the kit. I'll have to buy a new charging handle.
Shame all the local gun stores only have $60 ones.

You could try the link below and buy their dedicated 22 charging handle, or call their tech support line. They were great when I had an issue with mine.

https://www.cmmginc.com/shop/charging-handle-assembly-22arc/

Yup, it's the radius, or lack of, right at the nose of the charging handle. My 9mm locked up when I first got it, same issue, and I played hell figuring it out.

I have a couple older CHs and they all have a nicely radiused underside where they meet the gas key area. Some of the other handle I have are cut on that diagonal, like yours. Both styles will work with a regular AR bolt fine, but specialty bolts, .22 & 9mm, sometimes need that full radiused version.

You could probably take a small file and reshape the handle you have. I don't think it would matter much since there isn't much tension to draw back with a .22 conversion.

I wouldn't get the CMMG plastic charging handle. Drop it or hit it against something solid, it will break.

Dave N

I don't know, Dave, I have that CMMG plastic (delrin?) charging handle and I have banged it around pretty good and it's hung in there.  I didn't deliberately try to break it, but the rifle has been dropped a few times and I've banged the charging handle area while sliding behind barriers doing simulation drills a few times.  I expected some damage but except for scuffs on the ends of the charging handle, it's still ok.  Even the latch didn't break.  Maybe I just got lucky.

ETA: it really does keep spent cases from getting stuck, which is why I bought it in the first place.  It cured this occasional problem when I was using a BCM mod 4 charging handle.  Downside is that the CMMG handle isn't near as easy to quickly grab and charge the rifle like the BCM was.

Get the CMMG plastic handle - it fills in the un-needed parts of the charging handle, helping to reduce jams.