I give this little device a big thumbs up. I just got back from function testing it and it's sure nice having my .22LR dedicated AR operate like its bigger brothers. Bolt locks back on last round just like a normal AR. Stick in a fresh mag, press the bolt catch, and the bolt chambers a round/closes.

If you already have cmmg mags, then you can upgrade them with the new followers with no issues. If your using Black Dog Machine mags, you've got some mild sanding/fitting to do. I see myself just buying some bhoa ready mags from cmmg rather than taking the time to retrofit all my BDM mags. I'm lazy =)

If you're using a cienner type conversion bolt and wished your bolt catch actually functioned , this is definitely the thing to get.