oneb,
I owned a Ruger .44 Carbine in the early 70s that would not function properly. The owner's manual claimed that reduced power loads, lead loads, and even 180 grain loads may not allow the rifle to function properly. I was using various factory 240 grain, jacketed bullet loads. Disassembly and thorough cleaning never stopped the problem. So, back to Ruger the rifle went. They did fix it, even sent a repair itemization back with the rifle. If memory serves me, they replaced some of the magazine parts and removed a burr on the action somewhere. After that the rifle functioned okay, but it required cleaning after every 100 rounds or so to prevent jamming. You may want to contact Ruger. I have found their service department to be reasonable in cost and very customer oriented.