My dream handgun it uses no percussion caps as the ignition source and instead use primers. They're cheaper, they won't get stuck in the actions of revolvers, they don't blow themselves apart and also, I can use a firing pin in the revolver so it would make cartridge conversions easier to make and use.
I think it's already "doable" though not yet in a revolver...,
First, cartridge conversion using a single firing pin was one of the original ways that 1858 Remington Revolvers were modified to take cylinders that held cartridges...those cylinders were very very similar to the modern cylinders
http://www.taylorsfirearms.com/hand...ions/1858-remington-conversion-cylinders.html , and they are where the idea was born. It's not a new thing.
The modern conversion cylinders use 6 firing pins, one per chamber, while the original Remington conversions had a firing pin added to the hammer, that went through a hole in the cylinder base plate to strike the primers on the cartridges held within. The firing pin was held in place on the hammer by a single screw with the idea that the shooter could, if cartridges were scarce, remove the firing screw and thus remove the firing pin, and replace the old cap fired cylinder into the revolver, and use it old style until cartridges could be obtained.
So you're thinking of converting a fixed cylinder that takes powder, to firing with primers. Well you might be able to come up with a cylinder that has threads to accept a primer conversion of a caplock.
https://www.cabelas.com/product/Davide-Pedersoli-Primer-Nipple-Conversion-Kit/1608590.uts ..., though these can be bulky. Here's another one that is less cumbersome
http://www.warrencustomoutdoor.com/mag-spark.html, but may be still too big. So something along that idea, which would maintain the handgun's lack of cartridge use, and thus not come under cartridge-gun bans.
I most definitely would NOT make it take smokeless powder. For the very fact that smokeless is a very different creature than black powder, and you'd need chambers sooo shallow to prevent the shooter from using too much nitro powder to over pressure your concept revolver's cylinder. Typically chambers use at least 20 grains. So Imagine you made your cylinders to use Lil Gun or W296 to give your customer a good load similar to a "hot" BP load for a .45 Colt? Waaay too easy for the shooter to use something like W231, Unique, or A No. 5 and end up loading
twice the powder used for a super hot "Encore or Ruger Only" .45 load.
Sure, you could make your cylinder from steel capable of handling such loads, but what will that do to overall price?
Stay with black powder, and in fact some places the folks might be a market for your idea, they are restricted from handling modern powder in case it's used to make an IED....
I mentioned it's already something that might be done. Perhaps a Howdah
https://www.davide-pedersoli.com/tipologia-prodotti.asp/l_en/idt_29/pistols-howdah-hunter.html converted over to use primers? The drawback for the Howdah is that the shooter is basically walking around like Mad Max.
How about a Bond Arms PT2A?
https://bondarms.com/bond-arms-hand...oft&utm_campaign=PT2A&utm_content=gun-carosel? They are long enough to take a .410 shotgun shell. (they also have a 6" barreled "Texan" and a .357 long barreled "Snake Slayer"...all are long enough) Only have the barrels made with the breech side closed, AND with a pair of pockets to hold the primers. You'd still have enough room to load powder and ball or a modern style bullet made with softer lead. They are already designed with a firing pin, all that is needed is a barrel modification. The steel is made to take smokeless pistol/shotgun loads, so you could possibly use loose, smokeless powder, but I still think you should stick to black powder or a substitute. Only two shots...true...., so the person should carry a brace of the things.
LD