My 1/2" impact was always wimpy,once I discovered the inlet fitting was 1/4 and not 3/8 like the hose it worked like it was supposed too.The 1/4 in fitting that I didn't know about.
1/4 NPT (Nominal pipe thread--cut tapered not rolled) is the thread for the connection and the OD of the fitting and is fixed at 0.540" if you plan to cut threads with a die. The ID of the fitting can vary. Too thin a wall and a drop on the concrete floor with a heavy air tool of any weight is a liability.I might be having a brain fart here. Isn’t 1/4 the standard? I use 1/4 high flow myself. And 3/8 hose. Maybe I’m missing something.