He is using a Marlin lever action guide gun 45-70 the gun is 2 months old he is handloading now and very safe with pressure and so forth he has loaded some fairly mild 300 gr hollowpints behind a charge of 54 gr IMR 3031 veclocity from a chronograph is 1500 fps, idealy he wants more velocity what amount of xcharge would you use? no signs of pressure whatsover thanks