I've seen the South Africans shooting the new H&N 40 grain slugs at 1000(?) FPS (90 FPE), and am wondering how high of a reg. pressure is used, if the reg. is stock, what sort of hammer spring and weights are used to get this FPE and overcome the high back pressure on the valve?
The reason I ask is that I had recently tuned a .22 Maverick, and used the .30 hammer weight with the power kit weights (washers), Ernest transfer port, Superior Heavy liner, 155 bar reg. pressure, and got about 950 FPS with NSA 31.2 grain slugs (62.5 FPE).
So can someone explain the magic to get 90 FPE from a .22 caliber Impact (I'm assuming is like 180 to 190 bar reg. pressure and all that goes with it)? Is it reliable? Heavier valve components and high pressure reg.?
The reason I ask is that I had recently tuned a .22 Maverick, and used the .30 hammer weight with the power kit weights (washers), Ernest transfer port, Superior Heavy liner, 155 bar reg. pressure, and got about 950 FPS with NSA 31.2 grain slugs (62.5 FPE).
So can someone explain the magic to get 90 FPE from a .22 caliber Impact (I'm assuming is like 180 to 190 bar reg. pressure and all that goes with it)? Is it reliable? Heavier valve components and high pressure reg.?