.251 TCR- It’s a Thing!

.251 Tinker Centerfire Rimmed (TCR) loaded with 31gr. LHPs, 38gr. LSWCs and 35 gr. Gold Dot Hollow Points

Regular readers will be familiar with this cartridge already, but here’s a refresher for new readers.

The Cartridge

Earlier this year I got to thinking that maybe a center-fire .25-caliber cartridge for revolvers might be a Good Thing. The concept was to be able to load anything from indoor ‘gallery’ loads to something with a bit more oomf than a .22 Magnum. Specifically this would be developed for handguns, so it would not be as obnoxious to fire as cartridges like .22 Magnum, whose loads are designed primarily for use in rifles.

The lowest powered loads would use .25 caliber airgun pellets, possibly propelled by a primer. The highest-powered would use jacketed rounds like the Speer 35gr. Gold Dot. The intent was for this to be a cartridge with center-fire reliability and fully re-loadable, but able to duplicate or exceed the full range of .22 rimfire cartridges.

The cartridge is based on the .22 Hornet cartridge, significantly modified into a straight-walled case for use in revolvers. I decided it should use .251 bullets, the same as are used in .25 ACP. This would also make swaging lead rounds relatively simple, and allow the use of .25-caliber airgun pellets in the low powered loads.

.251 TCR (top) with it’s parent case, .22 Hornet

Commercially available bullets are very limited- basically you can get a 50gr FMCRN or a .35gr. Gold Dot hollow-point. However by reaming a .250 hole in a block of steel I could easily swage 1/4″ lead wire into bullets. I did this, and made a punch to produce a semi-wadcutter profile.

The brass has an outside diameter of .275″ and is .980″ long. The rim diameter is approximately .350″.

The Bullets

As mentioned the selection of .250-.251 bullets is limited. To start I bought some PPU 50gr. FMCRN, a couple hundred Speer 35gr. Gold Dot Hollow-points, and a tin of H&N Grizzly .31gr. LHP airgun pellets. I also swaged some 38gr. LSWCs. I figured this to be a decent sampling to start with.

The Gun

Naturally there are no guns chambered for a completely new cartridge, and I went through several ideas before settling on an Uberti 1873 BP. This is a bit of an oddball; it’s a cap-and-ball revolver built on their 1873 frame, primarily for sale in countries where modern cartridge firearms are difficult to own. I picked one up cheap, intending to convert it to fire metallic cartridges. I went so far as to make a .45 Colt cylinder for it but never completed the gun.

The Uberti 1873 BP with a section of .25 ACP barrel liner from JT’s, courtesy of Magnumwheelman

Let me tell you, if you come across one of these guns cheap with the notion that you can drop a .45 Colt cylinder in and fire cartridges you’ve got another think coming. Not going to go into detail right now, but Uberti has employed several tricks to prevent you from doing so. If you aren’t a skilled metalworker I would just spend the extra money to get a proper cartridge version to begin with.

The original intent was to retain the 4-5/8″ barrel, but it turned out my reamer was too short, and I had to cut the barrel top 3-1/2″. I bored out the barrel and turned a section of the barrel liner (who are they kidding? At 9/16″ in diameter this is a barrel!) and press-fit it into the reamed barrel, then cut-and-crowned it at the muzzle. I flattened the sides of the barrel to produce a ‘slab-sided’ look, then moved on to the cylinder.

I removed the nipples from the back of the cylinder, then bored the chambers out and reamed them to .454″, then turned down sections of 4140 round bar to fit, liberally slathered them with Loctite Red and press-fit them into the chambers. Afterwards I line-bored the chambers, reamed them to .250, then reamed them from the breech-end to .275 to accommodate the cartridges.

Finished- the first gun to chamber this cartridge, and likely to remain the only… at least until I make another.

Sort of a ‘Sheriff’s Model,’ but it will do for now. I’d planned to shorten the ejector and mount it, but the chambers are so small this would entail significant modifications to the ejector… and it might not work. In the meantime the ejector-housing on the frame is in the way of simply using a rod to poke the empties out, so for now I just remove the cylinder for unloading. Eventually I plan to turn a proper cylinder for this, at which point I’ll revisit the whole ejector issue.

The Loads

For test purposes I loaded the initial rounds to land in the .25 ACP power range, and miraculously it actually worked out that way. As I am convalescing at the moment, and forbidden to do heavy work, I mucked about today with various loads to explore the envelope.

The first two test loads used Unique, and the second set done today used Power Pistol, which seems to suit this cartridge very well indeed. I attempted some primer-propelled loads using the H&N Grizzly pellets, but they tended to jam in the forcing cone, so these were not a good choice. I’ll increase my pellet selection and return to this effort later.

While I think it vanishingly unlikely that anyone will run out and attempt to duplicate my efforts here, I have to make the usual disclaimer. If you use this reloading data you do so at your own risk, and I assume no liability for the use or misuse of this data.

All loads use Federal #100 Small Pistol primers

Unique Loads

38gr LSWC- 1.5gr. 860 fps. 63 ft/lbs.

35gr GDHP- 1.5gr. 870 fps. 59 ft/lbs

Power Pistol Loads

38gr. LSWC- 2.0gr. 698 fps. 41 ft/lbs

38gr. LSWC- 2.7gr. 912 fps. 70 ft/lbs

50gr. FMC- 2.7gr. 831 fps. 77 ft/lbs

50gr. FMC- 3.5gr 1065 fps. 126 ft/lbs

35gr. GDHP- 2.7gr. 769 fps. 41 ft/lbs

35gr. GDHP- 3.5gr. 1214 fps. 115 ft/lbs

35gr. GDHP- 4.0gr. 1464 fps. 167 ft.lbs*

*This figure is suspect; I was only able to get a good reading on one round of this string. This should also be considered a Maximum Load using the Federal primer.

The goal of exceeding .22 magnum is certainly achieved! I was unable to discover a .22 WMR load that approached the muzzle energy of the most powerful load from a 3-1/2″ barrel.

It’s early days yet, but so far it’s looking like I’m achieving the benchmarks I set for this cartridge. The hallmarks I was looking for included versatility, and it seems that’s working out. I also have to say I am very pleased with Power Pistol; it seems to be a very good match for this round.

I want to try some heavier Semi-wadcutters and maybe even some wadcutters as well as the ultra-light loads, and there are interesting times ahead when I get set-up for gel testing! At this point I am inclined to call this experiment a success.

I also wanted to mention that I was surprised at the relatively tolerable muzzle-blast of even the hottest of these loads; they were nowhere near as loud and violent as .22 Magnum loads. An effect of the Power Pistol powder? I don’t know, but I am grateful! This round might even have potential as a low-recoil self-defense round.

Accuracy also was very good; at one point I realized I needed to start scattering my shots because I was slowly chewing a hole in my backstop!

I’ll keep you abreast of developments as I go.

Michael Tinker Pearce, 18 November 2019


2 thoughts on “.251 TCR- It’s a Thing!

  1. Nigel Barker

    What an interesting journey this is. 31 gr. eh, that’s a pretty heavy airgun pellet. But it’s also a very inexpensive bullet. I’d be interested to see how it behaves with a smidgen of powder behind it.


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