I have not shot a 20 inch 416, but my Rigby came from the factory with a 22 inch barrel and a full length Mannlicher stock. My 400 g reloads and factory ammo chrono at ~2350 fps. I did have to move from RL25 to RL22, but am using slightly less than max powder load to get the desired velocity. I enjoy shooting it. Muzzle blast, muzzle jump, recoil etc are not noticeably different from any other big bore I have shot. Love the gun and hope to take a buff with it in May!