I've successfully shot X's out of my 16 twist CZ - but the 50gr. was a tich too long for that twist. I chucked them up in the small lathe and cut 1/8" off the base, leaving a 41gr. "X" bullets. These, driven by 13.3gr. Lil'Gun in the CZ or Ruger only, run right around 3,250fps and shot into just under .5" for 5 at 100 meters off the bags. I've not had to opportunity to use them on deer, moose or bear, but you just never know. Living in game-rich territory helps.