I've been down that road and made 200 ft lbs with modifications. I felt that it was being pushed past it's limits so I put that 800mm barrel in my Panthera and was able to make 215 ft lbs with 108 grain NSA slugs which I felt was right at it's maximum for power for the gun and bullet combo. I...
Good work. I shot a buck at 80yds opening morning and two does Sunday evening. Buck didn't have a clue what happened when he got hit, jumped and ran for about 20 yards, stopped for maybe 10 seconds then tipped over. Used Panthera 35 cal with 108gr NSA at 950ish. Has 800mm barrel and a Emperor...
I do lube the O-ring with silicone oil before putting it in and a little on the bottom of the gauge. Have done this with many Impact gauges with no failures, usually hand tight or just a touch more.