My distance from a suitable range, and my budget required that I discover a new solution to your same issue. This happened accidentally.
Recently I helped a friend build a heavy wooden structure held together with 40d nails (5" x about 1/4", using a baby 2 1/2 lb. sledge. A lot of nail pounding !!! We did this for several weekends and allowing a day or three for this 68 yr old to recover, I discovered how much less grip pressure I needed to keep the G20 with my heavy handloads on target for the follow-ups. I use a old soft railroad tie and a 2 1/2 sledge using L & R hands separately to pound on at least once a week. Works great.