15 rounds in a 22 target pistol is reasonable and usefull for target practice but the M16 only carried 20 rounds when it was introduced and even now only carries 30. One magazine change isn't going to slow you down much.
again, i'm not sure a capacity limit is going to necessarily solve the problem it's designed for, but just pointing out that such a limit is credited for stopping a specific mass shooting in canada. i think more than 30 is probably too much, and i don't have a problem with limiting to 10 or 15 only. the problem is to be effective, the ban has to necessarily cover all previously purchased items and i don't see more than about 20% of gun owners trading in their current stock for limited capacity ones.
"That's the trouble with political jokes in this country... they get elected!" -- Dave Lippman