Quote Originally Posted by themariners View Post
the Hmr head doesent weight 18 grains quite a bit more
Um, no one mentioned HMR, which are commonly 17 or 20 gr loads and gets nowhere near your quoted figures (2250ish with a 20gr) using modern powder, ok probably only only 5 gr of powder but smaller cartridge so higher pressure, tripling the powder won't more than double the velocity.

If you're referring to Guesty's post then he is talking .17 hornet, same cartridge as yours necked down and renowned as a bit of a speed demon for capacity, yet it falls 1000 fps short of your reported figure without the wad slowing things down and using modern powder.