ruger MK 3 22/45 FTF

Had a problem at the range today that boggles the mind ! need any help or suggestions that might solve or at least give me a clue.

After firing about 100 rounds almost flawlessly, using Std Velocity Armscor FMJ, I switched to a box of Hi vel HP. also by Armscor.
Alternating using 2 mags with 10 rounds each ;
mag #1 no problem
mag #2 9th round had a Failure to Feed.
mag #1 9th round had a Failure to Feed.
mag # 2 9th round had a Failure to Feed.
mag # 1 9th round had a Failure to Feed.

Only clue is that each bullet was slightly askew when removed.

Thanks for any help,

Oldkvet