Hi Snuffy,
I have not worked on that particular rifle-
However, cutting the mainspring to reduce the power and tame the shot cycle is a common practice, but takes some care to do right. Do a Google search and you should find some info on the process. Do NOT try to disassemble any spring gun without a spring compressor! Some mainsprings have a lot of preload tension and can send parts flying at dangerous speed. Safety First!
John
PS-I sent you a message