When it comes to pellet weights. I shot alot of pellets through the guns I own to find the best and when it came down to the 10.65 gr pellets I only shoot them through the 350 mag. My hunter and Big cat shot them in the low 800's so the actual power (fpe) was close to the same of a 7.33-8.8 gr at low to mid 900's.(Velocity x Velocity x pellet weight / 450240= FPE) The difference was accuracy. My hunter and Big cat shoot much more accurately with lighter pellets. My 350 slings them so fast that they are not acceptable in the accuracy department. Big lead falls alot at longer range. Light lead has a flatter trajectory. Also heavier lead takes more energy to get moving, so more strain on the internals of the gun. I have run them through the F-1 Chrony at 20 inches from the barrel and about 30 ft from the barrel to check this.
SO out of my hunter and big cat I shoot 7.33-8.4 gr JSB's and out of the 350 I shoot 10.65 gr H&N. My Gamo hunter will punch through a 1 gallon milk jug full of water at 35 ft and go through a squirrel from left eye to right shoulder at 18 yards. Thats plenty of power in my eyes. The 350 has blown through everything but the back stops.
And lead free super light weight pellets are CRAP! super dooper fast but cant hit the broad side of a barn it worthless. Down with PBA AMMO!