I've got a bullberry 20 inch bull barrel that shoots winchester 40 grain FMJ and JHPs into one ragged hole at 50 yards, it shoots the winchester dynapoint into about an inch and a quarter and CCI FMJs into about an inch and a half. I haven't gotten any other brands, but will try them when I can get my hands on some...Federal, remington, who ever else makes them.
The key to success with the 22 mag is finding the ammo your gun shoots best and then sticking with it. I have never been a 22 mag fan, but this barrel shoots much better than my bullberry 22 hornet barrel on a routine basis. I actually bought the barrel to rechamber to a 221 fireball, but it is so consistent that would be a crime...the hornet may get the fireball rechamber...
regards,
graycg