i got some 9mm nato ammo from walmart...was at the range and the first round locked the gun up...managed to get the cylinder open,noticed the casing was stuck in the cylinder..i tapped the casing out with a dowel and a hammer ... i tried to fire another round in case it was just a fluke..gun locked up again...got the cylinder open and had to hit the casing out with a dowel again....i will stay away from 9mm nato from now on...the gun shoots everything else great..