The one thing that many reloaders miss in loading the 30 carbine is that it loads just like a pistol with a straight wall case, without a rim. The case headspace's on the case mouth and with pressure, multiple reloads, the brass grows, plus the case mouth should be expanded for seating a cast bullet, especially and then crimped, only to a straight case, so the cartridge headspace is maintained. Lead shaving on the mouth of multiple loaded cases can build up, causing worn disconnector issues or a round to be fired with the bolt slightly out of battery. I have personally seen a 30 M-1 shear a right side bolt lug off, in a firing slightly out battery, incident. Examination of the remaining ammo indicated lead shavings w lube mixed was the cause, when combined with a slightly worn disconnector. Luckily no one was to the right of the shooter on the line. Took a new disconnector and bolt for repair. The 110-130 RN cast plain base works well for me when sized to groove diameter if PCed nose down in a rack. My 30 M-1s shoot to 1" at 50-100 with H-110/296. Plus the bullet shoots to the factory ammo POA. I prefer the Lyman 130 grain PBRN, but have owned the mould for many decades.
I have carried mine on stake-outs with the sheriff's department, at perp's houses, with J bullets, of course. Handy rifle for inside a vehicle, CQB or home defense.
The intent of the 30 Carbine was to replace the sidearm, not to be a battle rifle. Most noted disabling shot failures were when the little carbine was used as a battle rifle. Use of equipment beyond its intended purpose is almost a classic SOP of the military.