I'm new to this forum and hope you welcome me. I need some help with a Steyr Match 88,I purchased this for my Grandson to use in BR, He grew out of it and it's been in my safe resting, A year ago I had it resealed by Pilkington. I tried to refill the CO2 Cartridge, and I guess I'm doing it wrong. How do I find out how much CO2 I'm putting in? Can't find the ls manual that came with the gun. Purchased in 1998. Any Help is appreciated.

Fred J