About 1894 in France, a center fire round was created that was intended for bicycle riders to be used against attacking dogs. Thus the 5.75 Velo Dog was born. It was a black powder load, and was no more powerful than a .22 short, so given the latter was much more available and cheaper to shoot, the later versions of the initial gun was chambered in .22 rimfire, and the 5.75 Velo Dog became a fun foot note in load history.
The problem we still have with rimfire is reliability, the reason there's only two surviving rimfire families left, based on the original .22 short from 1857 updated to the .22 long rifle in 1884 and Winchester's 1890 .22 WRF warmed over and fixed in 1959 becoming the .22 WMRF. Whenever we talk about self defense reliability becomes a key factor and the only thing keeping rimfire chambered guns on the market is their capacity in small revolvers is usually 6-8 rounds and the revolver manual of arms for a misfire is (duh) pull the trigger again. Also even the magnum rounds out of a 2" barrel generate less than 100ft/lbs and many just create around 65ft/lbs the same as a .22lr. However it's enough to penetrate, even at those low energies as the frontal area is small, and sheds energy slowly.
I'm pretty fond of .32's for carry. Understand I'm a civilian, not a LEO, and my need in my estimation for 15 rounds is zero. Self defense for me is better served by a gun with no safety, the simplest of recoveries if something goes wrong, a round in the chamber or chambered by the time the first trigger pull is complete and with a heavy trigger and 150 years of history telling me a heavy trigger in a carry piece is a good idea. There's no legend of Revolver Leg. Also if it's a small gun I want the one good grip to be in my hand, one that doesn't require both hands to clear a jam and I can't push it out of battery jamming it in an assailant's side. And those .32s were the standard for concealed carry by civilians up to WWII. Since then the energies doubled then quadrupled and I'm quite convinced bad guys aren't any tougher than they were in 1890.
Thinking about .22 for self defense, it's never been addressed very well in revolvers. The FN 5.7 shows it can be an effective handgun round. So I decided to take a look and think about a centerfire .22, and Velo Dog popped up. Hmm, it has a rim at least.
The Velo Dog round was 1.4" long, so I'm going to suggest that the tried and true method of making the round longer in revolvers, and to put it in the same cylinder with the identical frame and cylinder spacing of chamber to axis as a .38spl, I suggest lengthen it to 1.5". So a theoretical .22 VelodogMag (VDM) would have a case about 1.26" long.
The .327 magnum is speced at 45kpsi, which is quite a bit more than the 9mm at 35kpsi. So measuring up a couple of examples of .327, we can safely set a wall thickness for a a similar pressure round in .22 VDM, although being smaller in diameter the actual force the cylinder sees in actually much less than the .327 cylinder does. So I'm erring way on the side of a large safety factor here.
Also I think we have a large amount of choices for projectiles, but the .224"dia 55gr the .223 shoots I think would be a good choice, it will penetrate deeply and and comes in softpoint and hollowpoint varieties, although we may have to open the hollow point up a bit to expand at pistol velocities.
Figuring out what the internal ballistics would look like, in Quickload I tried first a powder I know was designed for .22lr and works well in handgun loads, Vihtavuori 3N37. Pushing 100% of the case fill, I get 36kpsi. Trying a faster powder, Nitro 100 at 100% fill gets me to 42kpsi. Good so far. Trying Bullseye, 100% fill gets me to 48kpsi, over our target of 45kpsi, but only by 7% or so. Seems like this thing could be done safely.
Muzzle energies are pretty close to .22lr *rifle* energies out of short barrels, between 160 and 200 ft/lbs, or about 3x the energy of most .22s out of a short barrel. An these energies are coming with a 55gr bullet with the same frontal area as a 40gr round and should get some significantly deeper penetration.
OK, what about the gun? Well the constant complaint about revolvers is capacity. So if we restrict ourselves to the easy thing for the gun companies to do, 8 shot guns are very easy in the standard 1.3"dia small revolver cylinder. Same frame size and axis to chamber distance, it's two more holes which is exactly what they did with the .22 versions of small frame revolvers. Charter Arms recently figured out they had a frame combo they could put 7 rounds of .32 H&R mag into (the Bulldog frame I think, so not very small), so there are paths forward to getting revolvers competitive with autos in this way. If someone is willing to tool for a .32/.22 frame, as S&W once did, then in a small frame 7 shot .32 and 9 shot .22VDM is an easy reach. Bump the cylinder size to 1.5" and 12 rounds can be fit. Now we are talking.
So that's how I entertained myself today. How you were entertained reading it, and add any ideas you have.
The problem we still have with rimfire is reliability, the reason there's only two surviving rimfire families left, based on the original .22 short from 1857 updated to the .22 long rifle in 1884 and Winchester's 1890 .22 WRF warmed over and fixed in 1959 becoming the .22 WMRF. Whenever we talk about self defense reliability becomes a key factor and the only thing keeping rimfire chambered guns on the market is their capacity in small revolvers is usually 6-8 rounds and the revolver manual of arms for a misfire is (duh) pull the trigger again. Also even the magnum rounds out of a 2" barrel generate less than 100ft/lbs and many just create around 65ft/lbs the same as a .22lr. However it's enough to penetrate, even at those low energies as the frontal area is small, and sheds energy slowly.
I'm pretty fond of .32's for carry. Understand I'm a civilian, not a LEO, and my need in my estimation for 15 rounds is zero. Self defense for me is better served by a gun with no safety, the simplest of recoveries if something goes wrong, a round in the chamber or chambered by the time the first trigger pull is complete and with a heavy trigger and 150 years of history telling me a heavy trigger in a carry piece is a good idea. There's no legend of Revolver Leg. Also if it's a small gun I want the one good grip to be in my hand, one that doesn't require both hands to clear a jam and I can't push it out of battery jamming it in an assailant's side. And those .32s were the standard for concealed carry by civilians up to WWII. Since then the energies doubled then quadrupled and I'm quite convinced bad guys aren't any tougher than they were in 1890.
Thinking about .22 for self defense, it's never been addressed very well in revolvers. The FN 5.7 shows it can be an effective handgun round. So I decided to take a look and think about a centerfire .22, and Velo Dog popped up. Hmm, it has a rim at least.
The Velo Dog round was 1.4" long, so I'm going to suggest that the tried and true method of making the round longer in revolvers, and to put it in the same cylinder with the identical frame and cylinder spacing of chamber to axis as a .38spl, I suggest lengthen it to 1.5". So a theoretical .22 VelodogMag (VDM) would have a case about 1.26" long.
The .327 magnum is speced at 45kpsi, which is quite a bit more than the 9mm at 35kpsi. So measuring up a couple of examples of .327, we can safely set a wall thickness for a a similar pressure round in .22 VDM, although being smaller in diameter the actual force the cylinder sees in actually much less than the .327 cylinder does. So I'm erring way on the side of a large safety factor here.
Also I think we have a large amount of choices for projectiles, but the .224"dia 55gr the .223 shoots I think would be a good choice, it will penetrate deeply and and comes in softpoint and hollowpoint varieties, although we may have to open the hollow point up a bit to expand at pistol velocities.
Figuring out what the internal ballistics would look like, in Quickload I tried first a powder I know was designed for .22lr and works well in handgun loads, Vihtavuori 3N37. Pushing 100% of the case fill, I get 36kpsi. Trying a faster powder, Nitro 100 at 100% fill gets me to 42kpsi. Good so far. Trying Bullseye, 100% fill gets me to 48kpsi, over our target of 45kpsi, but only by 7% or so. Seems like this thing could be done safely.
Muzzle energies are pretty close to .22lr *rifle* energies out of short barrels, between 160 and 200 ft/lbs, or about 3x the energy of most .22s out of a short barrel. An these energies are coming with a 55gr bullet with the same frontal area as a 40gr round and should get some significantly deeper penetration.
OK, what about the gun? Well the constant complaint about revolvers is capacity. So if we restrict ourselves to the easy thing for the gun companies to do, 8 shot guns are very easy in the standard 1.3"dia small revolver cylinder. Same frame size and axis to chamber distance, it's two more holes which is exactly what they did with the .22 versions of small frame revolvers. Charter Arms recently figured out they had a frame combo they could put 7 rounds of .32 H&R mag into (the Bulldog frame I think, so not very small), so there are paths forward to getting revolvers competitive with autos in this way. If someone is willing to tool for a .32/.22 frame, as S&W once did, then in a small frame 7 shot .32 and 9 shot .22VDM is an easy reach. Bump the cylinder size to 1.5" and 12 rounds can be fit. Now we are talking.
So that's how I entertained myself today. How you were entertained reading it, and add any ideas you have.