What .17, .19, .20, or .22 cartridges are good in a 10" T/C barrel?

Related to my thread in Handguns about finding a good selection of 5 different T/C barrels to cover a wide range of shooting, I'm pondering what's best in .22 or smaller for a 10" or 14" barrel. It seems like a lot of those rounds might need considerably more barrel to get up to speed, so what are all good rounds that take advantage and aren't just turning powder into recoil and blast?

I started out thinking about .22 Hornet, but the brass fragility is dismaying. So I pondered things like .218 Bee and .224 Harvey K-Chuck, and then started thinking about the smaller rounds, which would also be cool contrast to more common bores. I'd thought for a bit that 5mm Remington Magnum Rimfire sounds great, especially since it has the 5mm Craig centerfire alternative, so I could either shoot the new factory 5mm loads or flip the switch to centerfire and shoot Craig handload, all in the same barrel. Not too many cartridges available in identical rim and center variants, and almost no guns other than T/C that switch so easily.

I'd read too that 5mm Rem loses very little speed going from rifle to pistol, so that's positive. However, other .20 rounds like the VarTarg leave them it in the dust. But then again maybe I don't need so much velocity and having low blast and scrimping on powder is good.

I don't have a particular purpose since I don't generally hunt, so just punching paper, ringing gongs. I do like silhouette shooting, but I think I'm set on 6.5 TCU for that (and that's why I'm looking small for contrast instead of .256 Win).

Any thoughts on such smallbores that are simply fun to shoot and load for?

If you want quicker/cheaper than custom Ed's Contenders has 12" .22 TCM Contender barrels in their "Hot" section: http://www.edstc.com/hot.html

If I go .22 bore, which honestly makes a lot of sense for bullet availability, I think .221 Fireball would be my top choice at this point. Not sure I want to go as small as .17. But the .20 bore still holds some attention for me, so I think it'll come down to one of those vs the Fireball. I found a good sum-up list of the many .20 wildcats on Saubier:

http://www.saubier.com/forum/archive/index.php/t-344.html said:

Recognized Twenty Caliber Wildcats
(listed from smallest volume to largest)
5mm Craig (5mm Remington Magnum)
5mm Schroeder (5mm Remington Magnum)
5mm Shrike (5.7x28 case)
5mm Skeeter (25 auto)
20 Eichelberger Dart (25 auto)
20 Squirrel (22 Hornet)
20 Mink (???)
20 Ackley Hornet (22 Hornet)
20 Ackley Bee (218 Bee)
20 Killer Bee (218 Bee)
20/30 Carbine (30 Carbine)
20 VarTarg (221 Fireball)
20/222 (222 Remington)
20 VarTarg Turbo (222 Remington)
20 Bobcat (222 Remington)
20 Duster (222 Remington)
20 Terminator (222 Remington Magnum)
20 TNT (17 Remington)
20 Practical (223 Remington)
20 Tactical (223 Remington)
20 PPC (22PPC or 6PPC)
20 Little Nasty (20 PPC with the reamer run in short)
20 Pup (22PPC or 6PPC)
20 Worth, Bishop, Bowerman (6PPC)
20 BR (6mm Remington Benchrest)
20 Ferguson Ace (6mm Remington Benchrest)
20 Dasher (6mm Remington Benchrest)
20 BR Express (6mm Remington Benchrest)
20 Classic (30-30 Winchester)
20-250 (22-250 Remington)

Click to expand...

Not surprised that the 5mm Craig is basically the smallest. That one does have a lot of appeal for something mellow, plus the novelty of having a barrel that can be used either centerfire or rimfire. VarTarg looks to be one of the more efficient ones, maybe a good one out of short barrels? And of the ones between the VT and the Craig, the Squirrel and the Killer Bee jump out as cartridges I'll need to read up on.

Apparently people have had even more fun than usual finding names for the .20 wildcats...

Bumping my own old thread since I'm back buying T/C barrels.

Other than as already discussed above, anyone have any strong argument for any of these smallbore cartridges being uniquely suited to shorter (10"-14") barrel lengths? I'm really down with the idea of getting a sub-caliber bore (I already have a .22 Hornet to cover pure smallbore), but really looking for one where I'm not wasting powder on flash and bang, but to the degree possible am using it all to get velocity out of a short barrel.

As an update since I started the thread, I now have a .22 Hornet barrel for my Contender, which I mainly got since it's the go-to cartridge for Silhouette in the Field/Hunter's categories. Plus it'll cover me well for the same plinking tasks that I considered the .222 and .221 for, just more efficiently with less blast.

I've been looking into the .204 Ruger, but I'm seeing a lot of postings online where people far savvier than I have mentioned they and their friends buying 14" .204 barrels for the Contender and swiftly selling them as just not a good platform/cart combo. As I understand, unpleasant blast, poor efficiency, etc. Bulberry has a great article where they cut a 24" .204 barrel down an inch at a time and chronoed it, and said 23" was a clear optimal, and at 18" muzzle blast was getting nasty, and at 16" they couldn't even get a clean chrono read.

I'm a fan of small and efficient cartridges, so in the 17-19-20 category for a 10-14" barrel, I think my strongest candidates are .20 VarTarg (.20-221), .20 Squirrel (.20-22 Hornet, shortened down to an inch) .19 Calhoon (.19-22 Hornet), and 5mm Craig (centerfire 5mm RMR, I can find an old 5mm Contender barrel and use it for the centerfire too since Contender's have a firing-pin switch for rim to center). I think those four are all towards the smaller/efficient end and might fare better in short barrels, right?

Brainstorm on the .20 Squirrel: if it's made from a notably shortened Hornet, and I have a .22 Hornet barrel and will quickly have a collection of brass with split/crumpled necks after enough reloadings, maybe the Squirrel would be a good way to "recycle" that spoiled brass?

Though not completely comprehensive, this image lays out the range quite well: