Did it malfunction in one or both guns?
If it was just the Ruger, there might be some brass shavings around the firing pin that need to be cleaned out, or perhaps the breech area had some crud that did not allow the bolt to seat all the way down and made the strikes a bit light.
Did these rounds fire the second time you tried them, if you put them back in the gun? If they did, it's likely the gun has some crud in it or the priming mix didnt go all the way around the rim.
My Buckmark will start to misfire after three or four range sessions without cleaning it from build up of crud. I know what you're thinking...
