Should be enough
I started using about 100 ft of hose - 3/8 and 1/2 inch id. So pulled the hub (doing wheel bearings anyway) with wheel to the shop and used 15 ft of 1/4 hose with no improvement. The manual says the wrench uses 7 cfm @ 90 psi, and Milton says their 1/4 inch couplers are good for about 40 cfm. I have an older better quality 1/2 inch impact gun and the sound it makes has more authority. I guess you get what you pay for. I understand Harbor Frt has a "Earthquake" brand gun, but now I'm a little hesitant.Are you giving it enough air?
The little 1/4 inch industrial fittings, and 1/4 inch ID hoses are not big enough to feed the 3/4 inch guns with the air volume they need. If you must use fittings, use the 1/2 inch Auto style fittings, and a 3/8 inch ID hose.
-Chuck