What type of jam is it? Fail to eject (stovepipe or empty casing jammed in action), fail to extract (casing left in chamber), fail to feed (casings not leaving magazine, or jamming into feed ramp), fail to fire (dud, or light strike)....?
I have a 5.5" MKIII 22/45 SS Target that runs reliably when it's clean, but after 300 rds I need to clean it or it starts to have fail-to-ejects where it will leave an empty casing jammed into the action next to the fresh one that's feeding. Also, if I fire shorts or CB's out of it, they leave a stubborn lead ring in the chamber that causes the same thing. It really takes scrubbing with a bronze brush to get the ring out.
I don't believe I've heard of anyone ever limp wristing a ruger MK series .22. I'll have to try it next time I go out, but I don't think it's possible that his technique is causing the problem.
Probably just needs cleaning or different ammo.
I use federal champion in 500rd bricks of 50rd boxes (NOT the 525rd loose bulk pack, I haven't had the same luck with that stuff), CCI stingers, and Remington Subsonic (half inch 25yd groups) in mine with no problems. I used to reccomend federal american eagle, but after trying the federal champion in the 500rd bricks I don't buy anything else in bulk. It's very consistent for the price. I've heard good things about the CCI mini mags, but they are pricey, and the federal shoots well for me.