What are you running for a psi out of the hose? I have found with air tools, is there is definitely a get what you pay for status. A lot of the cheaper ones don't have a very high torque setting. I'd check on the gun to see if it is adjustable at all, and try to increase the psi from the regulator and see if it gives it a boost. Make sure your air hose is at least a 3/8" ID hose and not a 1/4". How long is your hose? You might try a shorter hose if your current hose is pretty long. Longer hoses lose pressure. Your tank is likely too small as well.