Good thread, Loony Dan.
Dan is dodging a bit, as he is at Doctorate level (he's the Campfire Jesuit that was on a quest for 22 rimfire substitutes) and probably found (created) a well found avenue.
Perhaps cartridges mentioned are in order.
I can speak only for myself, but I really enjoy handguns. I knew I couldn't afford to shoot them as much as I'd like or get the practice in to fully enjoy them without having more economical, yet precision bullets at hand.
Home brewing your projectiles keep what could be dormant arms functioning at top levels. This is especially true if one owns a gun in what is defunct at time when ammo ceases to exist or just isn't practical.
My cartridges that get this nod are:
Hornady defunct its only commercially available bullet (.222) and it shoots best with a cast (.224). The nominal size of the throats, which keeps forcing cone wear down.
22 Hornet- The Hornet doesn't need jacketed bullets to be at it's best. The 221, 222 and 223 also have a lot of practical room up to 3,000 fps. Someone mentioned 22 moulds. I have a Herter's, two NEI's and an LBT that cover 38-70 grains. 22's, within reason, have a ton of potential and a lot of experimentation with a minimum amount of expenditure in alloy and funds.This is also the best "trainer" caliber out there. Anything in 22 teaches, simply because none in a handgun or rifle creates flinches.
32 S&W Long, 32 H&R, 32-20, 327 Federal, 30 Mauser and Tokarev, 30 Carbine
These 30 caliber handgun rounds have a ton of potential, all of them. There aren't many decent jacketed bullets that accommodate them at reduced levels, nor are there many that make them the ballistic devils they are all, quite literally, capable of. Imagine a load that knocks the pants off of the next larger caliber, the 357-358, with the same or exceedingly greater BC with the use of quieter or less of a "loud"powder charge. The 30 caliber handguns do easily what anything larger cannot do without more noise, pressure, racket and recoil: duplicate the 22 LR in noise, racket and a little step in recoil. They can be made easily to have the same flight path. Nothing larger has these attributes.
The 38 S&W
Not a dire need for most, but if one wants greater accuracy and a tailored load for this often owned but seldom used cartridge, casting is the route for best results. Using soft, undersized bullets for the throat is a half assed attempt at getting one to work at its best. The only reason for caring is there are some really decent irons in 38 S&W.
The rage on the Campfire seems to be 10mm Autos. It's odd I've been loading cast 180-200gr. fodder for several years for the 40 and 10mm without knowing how awesome they were. The loads that kept the guns fed never knew they would be bear stoppers or demand the price tags boutique companies load "custom" ammo for. My loads don't hobble and seem to have flatter noses than the ones deemed "best", but I'll shut up since Cor-Bon, others and Buffalo Bore have many buffaloed into buying stuff one can readily make oneself at a fraction of what bear defense is going for. We'll even not post the actual hardness tests of the over the counter component makers here....
The 41 caliber is mentioned here because few jacketed bullets exist for it, despite being a caliber that can readily be used in both rifle and handgun application.
In a handgun it's best cast options make it a step above the 35's and right with the 44's. It would be downright difficult to be proficient with a 41 caliber handgun shooting jacketed bullets without some decent dinero and an even better supply chain of components. It's being phased out.
Anyone that uses the 44 Special realizes two things: The 44 Magnum isn't really needed for most things and factory 44 Specials have a great deal room for improvement. It, along with the 45 Colt, are what "mid magnum" is all about. They can keel over most anything and if pepped up a bit beyond anemic factory levels can do so, easily, inside of a hundred yards and kill big game without a lot of nonsense, a flat nose and some decent bullet weight. If there are any factory loads with the bullets capable of what one can cast and load themselves can do, I am not aware of it.
I've used the 45-70 at Trapdoor levels, in Ruger #1's with 500 grain stompers and in Marlin level loads in handguns ad riflesfor hunting deer, all with home brewed cast bullets of some iteration.
A friend asked what we could get for his sister for her house gun, a Marlin 1895 carbine. Some Unique, a Winchester 410 shot cup, some Winchester 9 shot topped off by a pure lead .459 round ball mould creation crimped for cycling and as a "conversation" starter made a pretty good house defense item for a young single lady. Inside a house and not enough far outside of it, it would get things done.
Again, just another thing you can't go out and buy right now, if not ever.