I had same issue with wolf ammo during my first few hundred shots ... I took it home, cleaned, lubed, racked and went back to the range shooting 1 round at a time to see how often it wouldn't lock back, out of 200 rounds not 1 of them did anything screwy.
my gun now shoots perfectly with no FTF, FTE, or slide lock issues - keep the rails clean and add a drop of lube and it should sort everything out.
ps ... people kept telling me about my hand hitting the slide lock, but it wasn't the case for me. I purposely shot left handed, 2 handed low grasp (completely away from the slide release lever), etc and it didn't make a difference.