I've put a couple hundred rounds through the Gen4 G21 rental at my local range - I'm sure this thing has had thousands of rounds through it with minimal mx and cleaning.
All reloads. The only BTF came from brass bouncing off the lane dividers. I set the plastic tote they give you to carry your rental to my right against the lane divider (roughly to the gun's 4/5 o'clock) and probably 75-85% of my brass winds up in that tote. Seems to be pretty consistent.
Happy enough with it that I'll be buying one.
Good luck with yours.
Last edited by zj96sc; 08-08-2012 at 17:57..