My PD used to use Ultramax 9mm ammo for practice ammo with the MP-5's and our pistols. The ultramax is not super-reliable ammo. It shoots most of the time, but they have an occasional hiccup (almost always a FTF b/c of case size problems or an occasional bad primer). It's reman ammo, so it is to be expected. We never had any case failures of any kind. I'd say you'll be fine, and it'll give you practice with immediate action drills - a bonus.