I honestly dont look at harbor freight for some tools but i guess that shows i shouldnt count them out. Some of their stuff is pretty good though. For at the shop, my boss may go for a 200 dollar gun.
I have done something similar. Tied a larger tank tk the compressor tank and had alot of air but only a 3/8 line feedimg the gun. I never thought about a larger line feeding the gun. I think that might be why it took 2 days of pounding them. They werent rusty at all so i dont think they need penetrating oil. The gun is an ingersol rand capable 1000# i believe
Kinda same as pressure washers - air tools require the cfm, cubic feet per minute - to work. PSI means little with washers, it’s about gallons per minute, the volume - that is important.
You can use a torque wrench when tightening with the torque multiplier. It multiplies at the same ratio. So to tighten to 500 ft.lbs. you would set your torque wrench to 7.8 ft. lbs. Probably need to drop to an inch pound wrench for that low of a torque!