Cartridges You'd Like to See Invented or Developed

[spyderco monkey]

.251 Auto (6.35x21mm)


COL = 1.169" (same as 9x19)
SAAMI = 50kpsi (2x max of .25 ACP)
Cartridge weight = ~5g
Ballistics = 50gr @ ~1100fps from 3" pocket pistol barrel

Essentially, the '.251 Auto' is a lengthened, rimless version of the .25 ACP, run at high pressure. Because the .251 has such a narrow case, slim pocket pistols could use true double stack magazines while remaining thin, and even a short magazine would allow a large capacity.

A ~LCP/G42 sized pocket pistol could hold 15rds, while a spare G19 sized reload magazine could hold 20rds. Since the cartridge weight is only 5g (about 1/2 that of .380) the loaded 15+1 pocket pistol would be comparable in weight to a loaded 6+1 .380.

While the ballistics of '.251 Auto' would be marginal, they would be well above that of .25 ACP or .22lr, while offering much less recoil then .380 when fired from these tiny pocket pistols. So a shooter would have a low recoil, accurate, 15+1 pistol with good penetration that fits comfortably in a pocket.

[MistWolf]

I’d like to see the 45/70 and 45 Colt shortened enough to take out the air space and allow the same performance at moderate pressures with modern smokeless powders.

[mmc45414]

I’d like to see the 45/70 and 45 Colt shortened enough to take out the air space and allow the same performance at moderate pressures with modern smokeless powders.

I think that might be 454 Casull?

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[revolvergeek]

.251 Auto (6.35x21mm)


COL = 1.169" (same as 9x19)
SAAMI = 50kpsi (2x max of .25 ACP)
Cartridge weight = ~5g
Ballistics = 50gr @ ~1100fps from 3" pocket pistol barrel

Essentially, the '.251 Auto' is a lengthened, rimless version of the .25 ACP, run at high pressure. Because the .251 has such a narrow case, slim pocket pistols could use true double stack magazines while remaining thin, and even a short magazine would allow a large capacity.

A ~LCP/G42 sized pocket pistol could hold 15rds, while a spare G19 sized reload magazine could hold 20rds. Since the cartridge weight is only 5g (about 1/2 that of .380) the loaded 15+1 pocket pistol would be comparable in weight to a loaded 6+1 .380.

While the ballistics of '.251 Auto' would be marginal, they would be well above that of .25 ACP or .22lr, while offering much less recoil then .380 when fired from these tiny pocket pistols. So a shooter would have a low recoil, accurate, 15+1 pistol with good penetration that fits comfortably in a pocket.

Sounds fun to me. Put good sights and trigger on it and it would be a handy outdoors / trail gun for small stuff.

There is an older thread over on castboolits where someone did something kinda like this (but more intended for revolver use) with 5.7FN brass: Here

[Rick R]

I wonder what gauge that would work out to if you cut .50 cal cases off to three inches?

Hubel’s “12ga from Hell” is based on the .50 BMG.

https://thefiringline.com/forums/sho...d.php?t=197214

I’d think that some kind of round nosed plastic fairing over the shot to help feeding with a matching profile slug would be interesting in a magazine fed gun.

[MandoWookie]

Hubel’s “12ga from Hell” is based on the .50 BMG.

https://thefiringline.com/forums/sho...d.php?t=197214

I’d think that some kind of round nosed plastic fairing over the shot to help feeding with a matching profile slug would be interesting in a magazine fed gun.

I think that was tried before by a company several years ago. In a AR10 compatible upper I recall. Had black plastic shells that looked like huge pistol snap caps. I cannot remember what the company's name was though.

[the Schwartz]

.251 Auto (6.35x21mm)


COL = 1.169" (same as 9x19)
SAAMI = 50kpsi (2x max of .25 ACP)
Cartridge weight = ~5g
Ballistics = 50gr @ ~1100fps from 3" pocket pistol barrel

Essentially, the '.251 Auto' is a lengthened, rimless version of the .25 ACP, run at high pressure. Because the .251 has such a narrow case, slim pocket pistols could use true double stack magazines while remaining thin, and even a short magazine would allow a large capacity.

A ~LCP/G42 sized pocket pistol could hold 15rds, while a spare G19 sized reload magazine could hold 20rds. Since the cartridge weight is only 5g (about 1/2 that of .380) the loaded 15+1 pocket pistol would be comparable in weight to a loaded 6+1 .380.

While the ballistics of '.251 Auto' would be marginal, they would be well above that of .25 ACP or .22lr, while offering much less recoil then .380 when fired from these tiny pocket pistols. So a shooter would have a low recoil, accurate, 15+1 pistol with good penetration that fits comfortably in a pocket.

Paired with an appropriate JHP design, the .251 Auto is an interesting idea especially since its felt recoil would be quite mild making ''follow-up'' shots easy to execute.

While somewhat elevated pressure will be required to obtain 1,100 fps from a 3-inch barrel, I suspect that 50kpsi is probably higher than what will actually be needed. Assuming for the purpose of predicting the terminal performance of your conceptual design that the 50-grain JHP expands to 1.5x its initial diameter (≈ 0.377''), at 1,100 fps you can reasonably expect the (expanded) 50-grain JHP to penetrate to a depth of 11.4'' (mTHOR) to 12.70'' (Q-model). Predicted permanent wound cavity volume should be 1.04 in³ (mTHOR) to 1.16 in³ (Q-model).

The .251 Auto might not be a ''giant-killer'', but a couple of easily-controlled rounds fired COM might be enough to 'convince' someone intent on harming you that it is not worth it.

ETA: For those interested in how the MacPherson WTI model would evaluate the (assumed) performance of the .251 Auto, maximum penetration depth would be 11.23'' and permanent wound cavity volume would be 0.84 in³.

[4RNR]

OK, I'll play.

This is my conceptual design of the 0.375 USP (United States Police) cartridge. (the drawing is my own)

Attachment 76020

From a 4'' pistol barrel, it fires a 155-grain JHP (or FMJ) @ 1,215 fps or a 175-grain JHP (or FMJ) @ 1,075 fps.

Expansion of JHPs from the .375 USP is expected to be ≈1.5x caliber.

Predictive modeling with both the Q-model and the mTHOR model follows:

.375 USP 155-grain JHP
D_EXP = 0.565''
M = 155 grains
V = 1,215 fps

Q-model— Penetration Depth: 17.17 inches ; Wound Mass: 60.10 grams
mTHOR— Penetration Depth: 16.93 inches ; Wound Mass: 59.25 grams


.375 USP 175-grain JHP
D_EXP = 0.565''
M = 175 grains
V = 1,075 fps

Q-model— Penetration Depth: 17.98 inches ; Wound Mass: 62.93 grams
mTHOR— Penetration Depth: 17.46 inches ; Wound Mass: 61.11 grams

Reminds me of the 365tsw

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[MandoWookie]

I think that was tried before by a company several years ago. In a AR10 compatible upper I recall. Had black plastic shells that looked like huge pistol snap caps. I cannot remember what the company's name was though.

https://www.thefirearmblog.com/blog/...as-12-shotgun/

Found it. Used converted Magpul SR25 mags, and I recall the uppers showing up on CDNN not long after.
I dont know if they ever even got ammo production off the ground.

[MandoWookie]

https://www.thefirearmblog.com/blog/...as-12-shotgun/

Found it. Used converted Magpul SR25 mags, and I recall the uppers showing up on CDNN not long after.
I dont know if they ever even got ammo production off the ground.

https://www.brownells.com/shotgun-pa...rod142821.aspx

And here is a currently available iteration of the same concept, but it uses standard 12 gauge shells.