I would take a hard look at the use of the 140 grain bullet in a CZ 550. The 140 grain bullet just isn't long enough to get anywhere near the lands of the rifling and still have enough bullet to seat the bullet shank in the case neck so everything holds together well. That, plus the fact that the CZ barrels in 7x57mm have a 1x8.66 twist, which, I am told is for the heavier bullets, such as the 160 grain and the 175 grain variety. I cannot tell you if the 140 grain and the 1x8.66 twist would be a combo that would work well. Someone else might be able to offer a bit more advice on this subject than I. Anyway, I use Remington cases, Hornady 162 grain bullets, Federal 210 primers and H414 powder. With 48.2 grains of H414, and the bullet ogive seated .01 inch off the lands, I get a velocity of 2,815 fps average and groups that go between .4 and .5 inches from sandbag rests. With 48.9 grains of H414 and the 162 grainer seated .01 inch from the lands, the velocity is 2,855 fps and the group is .216 inch. I need to do some more experimentation with this load though. I don't know if that group size was a fluke or not. If I seat the bullet deeper in the case, say where the case mouth meets the canlures, the groups open up to one inch and sometimes 1.25 inch, which still is pretty good, but not near as good as those ranging from .4 to .5 inches. The way I look at it, if I can push the 162 grain bullet 2,815 fps+, then I have no need for a 140 grain bullet. I have used the 162 grain bullet from wild turkey, to javelina, to wild pig, to whitetail deer, to elk and everything has been one-shot kills. Hope this helps ... Tom Purdom
