I recently purchased a Bushmaster 22 lr upper. The mags were a tight fit but sanding the corners fixed the problem. It shot fine with only 1 malfunction. I was getting nice groups at 25 yards around .6 inch or so. I got a 2.5 inch 50 yard group. I have a tasco Pro point mounted on it. Its a fun little upper. Anyone know if there are going to be high cap mags for it.
Pat

I got a Bushy 22LR Carbon 15 upper a few days ago.  First problem was that the upper wouldn't seat well enough in an RRA lower to get the rear pin in. The rear lug in the upper that the pin goes through needed to have the bottom filed. (This may be a problem with RRA lowers as I saw this mentioned before in another thread.) Filing the bottom of the lug solved the problem.

The first few mags of ammo fired were terrible. There was no firing pin dent or very light dent on the malfunctioning rounds. (Federal 550 round Wally World bulk pack.) About every other round failed to fire. Mags were also a very tight fit in my RRA lower. After 3 or 4 mags, things got better rapidly. In the 5th thru 7th mags there were just a few filures. By 100 rounds failures were almost non-existant. Last 80 rounds had just one round hang up in the mag, no other failures. Also the mag fit is much better now.

I'm very satisfied with the function and accuracy is looking good too. Now if there were only some hi-cap mags.

I used sandpaper on the corners of the mags and now they fit well. They will not drop free but there no longer a pain to insert and remove. Its a fun little plinker. I would post a pic if I knew how.
Pat