I'll let you know how things go. I changed out the 130 spring I had for a 120 SHS which was to hand. Strangely it went up to 380, so careful about the quality of your spring. I'm sure an M130 SHS will push it to 400+
Thanks a lot, I'll certainly contemplate that. I'm on the hunt for a new spring so when I find I'll get the tech to do some tests