You can download the manual for your gun at this link http://www.cva.com/lifetime.html. It should be covered by the Inline Owners Manual and the max powder is probably 100gr loose powder and if it's the magnum version it may be approved for 150gr of pellets, please verify with the manual and/or call CVA. Since it is a 54 the max could be 10 or 20 grains more so verify for yourself. The best thing to do is to call CVA and give them the serial number to get the most accurate info on it. Good luck with it.