Ok, if you load your Sierra 180 Pro Hunters to 2400fps, and your Sierra 150 Pro Hunters to 2500fps (Both of those velocities are easily attainable with modern Handloads), they will have virtually the same trajectory out to 500yds.
I used a 200yd zero in the calculations, but it doesn't matter what you zero at as far as the trajectory is concerned.

Quote Originally Posted by newcastle View Post
I have been saving all my .303 brass for many years and started looking around for flat based bullets. The best i can find are the Sierra pro hunter 180 and 150 grain. 180 grain, being pretty similar to the the 174 grain Mk 7 cartridges , I'm assuming i'll be able to recreate them quite well. Does anyone in North America have a recipe for reloading the 150 grain bullets that gives a similar trajectory at least over the first 300 yards or so (so i can use the standard sighting)?