I suspect that this is the reason for most brass failure when reloading the Hornet. It might be possible to slightly streamline that shoulder by spinning it on a grinding wheel or belt sander.
The factory Hornet round with expanding bullet is too destructive for small game you want to eat. But light cast reloads won't be, and I think they will produce little or no brass lengthening, which is the other limitation on the standard Hornet's brass life.
I doubt if the .22 rimfire shortage will last long, or be repeated. If something of the kind comes up again, it is just as likely to be small rifle primers, and you need one of either whatever you shoot. I tend to think of the .22 rimfire magnum as a slightly pointless way of falling between two stools. It might have some point for the non-reloader who has a need for long shots at the inedible. In theory the inside lube round could be made more accurate than the heel bullet Long Rifle, as could the obsolete .22 WRF. But I don't think either of them ever were.
A snare and a delusion, in my opinion, are the various hypervelocity rounds made for the .22LR chamber. They could be loaded to give higher velocity with the same bullet, but aren't, because people would inevitably use them in old guns which are unsuitable for higher pressure. Instead they use a lighter and usually very hollow bullet to produce more velocity and energy as approximately LR pressures.
CCI Stingers are the ones I know best. Their energy advantage over Eley .22 LR High Velocity is about all gone at 100 yards. When fired into water, a HV solid impacts sideways and fairly lightly on a rock after about 16in. A hollow point begins expanding in the water, and impacts nose first with similar force at around half that distance. But the Stinger, at 8in., flies to pieces and doesn't reach the 8in. rock. The largest piece is a small button which was the base of that thimble shaped bullet. I'd say they give more leeway for bullet placement on small game at longish rimfire ranges. But they don't give longer range, and they don't give you a better chance with larger game.