I have the exact issue with my .30 Carbine Blackhawk. I have a fair number of Ruger single action revolvers, about half of which with cylinders for rimless cartridges, and the .30 is by far the most finicky of them all. If the brass is right at max length it's too long for the chambers and the cylinder won't want to turn. And then I get light primer strikes almost every time I take the gun out shooting. I thought it might be brass too short, but it's within spec. And after tearing it down, the same brass will fire the next time around. I switched to using small pistol (regular or magnum, depending on what powder I'm using), and it helps, but it's not 100%.
After one range session with a relatively high number of duds, I went home and measured the firing pin protrusion on all of my Ruger revolvers. While the .30 had the shortest, there were a couple others that were within a couple thousandths, and they have never had an issue. I have a .357 Blackhawk which has the next shortest firing pin protrusion. Checking with feeler gauges, it also has a similar clearance between the rear of the cartridge and where the firing pin comes through the rear of the receiver. I pulled down the failed cartridges and carefully pushed out the dud primers. I then seated them in some .38 Special brass and loaded them in the .357 revolver. All of them fired. And only took two strikes the rest all fired on the first try. I had struck them each twice in the .30 Carbine with no luck.
I have been thinking about getting an extra heavy hammer spring to see if that will help. I have also thought about just selling it and getting something else. But it shoots like a laser. Hitting an 8"x10" steel plate offhand at 50 yards is a breeze. And I can hit it offhand at 100 yards more often than not. Maybe that's no big feat for some, but I'm pretty happy with it. It's also better than I can do with most of my other handguns. If I could find a Blackhawk in .327 Fed, I might swap it out for that. They only made that one for a year or two. I already load for .32 H&R and some reason it seems silly to stock bullets that are only .003" difference in diameter.
I have shot very little factory ammo in mine. I did go buy a box of Herter's ammo just to see if they would run. They did all go bang, except for the one that was too long and wouldn't allow the cylinder to rotate. That case actually measured slightly over spec, but I suspect it wouldn't have been an issue in an M1 Carbine. But as I said, the revolver is finicky.
If you figure it out, let us know.
ETA: I haven't tried Rem primers in mine. I've used CCI 400, 450, and 500. All have had some duds. The pistol primers (CCI 500) seem to do the best, and showed no signs of excessive pressure. In fact, the cases usually just drop out of the chambers without having to use the ejector rod. I had wanted to try some small pistol magnum primers with H110 but apparently I'm out, so I've only used 450s with that powder.