Velocity? Well it kinda depends. I contacted Berrys Mfg. and they said to keep the velocities of their bullets to 1200 fps, yet my Uncles PC4 in .40 S&W pushes them at 1300+ fps with no sign of leading. Rainier, I believe, lists on their website to keep them around 1400 fps. I dont think youll have much problem with the mag, but Id be cautious with the 444. No serious problems will arise, you just might get leading because the plating gets stripped off, which defeats the purpouse of the plated bullet. Hope this helps.
Brian M.