A heat gun will produce as much or as little heating as you need. Just depends on the setting (Low vs. High), how far away you hold it from your work, and how long you apply it.
I think the hair drier is good for getting the piece warm but can't make it "hot" to the touch. This might be good enough. Worth trying. Especially since it may not be absolutely necessary to use heat anyway. As I said above, I didn't when pulled my BCM upper apart---just didn't occur to me to use heat. Duh. I admit that it might have made the job easier though. I was trying to remember exactly why the heck I did that anyway. It was to remove the delta ring assembly from the barrel. That has to come off the back of the barrel. My BCM upper came configured for a drop-in HG. I ran that for a while and then decided to install a Troy Alpha FF HG.
I think the hair drier is good for getting the piece warm but can't make it "hot" to the touch. This might be good enough. Worth trying. Especially since it may not be absolutely necessary to use heat anyway. As I said above, I didn't when pulled my BCM upper apart---just didn't occur to me to use heat. Duh. I admit that it might have made the job easier though. I was trying to remember exactly why the heck I did that anyway. It was to remove the delta ring assembly from the barrel. That has to come off the back of the barrel. My BCM upper came configured for a drop-in HG. I ran that for a while and then decided to install a Troy Alpha FF HG.