Due to the unavailability of certain components, I’ve resorted to 165 gr .311” Hi Tek coated Whitetail #4 from Missouri Bullet Co for my Marlin 336. I’ve been loading 16 gr IMR-4227 for about 1500 FPS, and they do very well. Question is, how fast can I go with these bullets? The bore slugs at .310”, and most cast data I have shows gas checked loads with a starting velocity much higher than what I’m doing. I have other powders, but have been afraid of using them because the start data is usually 1700-1800 FPS, and I don’t want to lead the barrel.