New Cartridge/Pistol Idea -- "6.8mm Kel-Tec"

[6.8KT]

This is a silly, arbitrary target. A lighter bullet will lose momentum and kinetic energy, penetration potential (SD)... all around bad... handgun bullets rely upon weight to do their job. Running a lighter bullet to get to 1,000fps just to say it runs 1000fps is just a waste of time. The round isn’t viable. Plain and simple. That’s why we haven’t seen any firearm or ammunition developer produce one.

The engineers and product designers at these companies do this for a living, every day, 2080 hours a year. Your idea has been thoroughly evaluated at some point - smaller diameter, higher capacity - and it’s been passed over because it just doesn’t work. They didn’t waste their time with it. You shouldn’t either.

I had settled on 1,000 fps to maximize velocity, but just under the trans-sonic range. Plus 1,000 fps is sort of the mean velocity of many calibers. Anyway... it doesn't matter now. This particular brain-child has been aborted.

 

[6.8KT]

Kel Tec won't even make anything in .45ACP, let alone invent a new cartridge.

The issue with centerfire mouse calibers is that the ammo is more expensive than 9mm, making them non-cost effective. Invent a cartridge the size of .25ACP with .38 Special muzzle energy, and priced at or below 9mm and then we'll talk.

The muzzle energy of Armscor's 22TCM is impressive, but the case is big and it's not a cheap round.

My idea was basically to keep the case as thin as possible, but the projectile as big as possible -- i.e., straight walled -- to maximize capacity. And yeah, I realized that a new cartridge is not going to go from nonexistent to cheap and plentiful overnight.

 

[6.8KT]

Bullet diameter matters, I don't want a 6.8mm handgun.

I don't think your proposed dimensions would hit the velocity goals due to the case capacity and the sectional density of the bullet compared with traditional pistol bullets. The narrower you make the bullet the less area there is to be affected by the chamber pressure. So if you have two different bore sizes with the same weight bullet and same powder capacity, the larger bore will generate a higher muzzle velocity at a lower chamber pressure. You might be able to match 380 muzzle energies in a high pressure (40K psi) locked breach pistol because a 380 is a really low pressure (21K psi) cartridge, but its still going to be shooting a tiny little projectile that will rely on expansion.

Yes. That was explained to me earlier in the thread, and it's a concept I hadn't considered before, but makes sense.

Using existing 6.8spc projectiles is not realistic as they will not expand at subsonic velocities.

My purpose of digging up existing projectiles was just to show that the projectile size/weight specifications could be met. The 'final form' of the bullet, in my thinking, would've been more round-nosed or JHP or semi-wadcutter.

 

[Jim Watson]

Well, don't give up.
Your next idea might be a winner.
But do study the history so you will know what has gone before, and the ballistics so you will know what is reasonably attainable.

 

[6.8KT]

That's been said many times in 3 pages. Those of us who actually build guns and do wildcat cartridges, who understand the internal and terminal ballistics, keep explaining why, but the OP isn't listening. He's clearly not familiar with the 6.5mm Bergmann and 7mm Nambu, both of which used bottleneck cases longer than 19mm and still delivered paltry performance. The 7.65 Mannlicher and 7.65 MAS were basically .30 cal versions of what the OP is proposing, and they barely manage to produce his 85 gr. @ 1,000 FPS numbers from their larger cases.

I am familiar with those cartridges because I took a close look at this list https://en.wikipedia.org/wiki/List_of_handgun_cartridges before settling on 6.8mm. I even mentioned 6.5 Bergmann earlier in the thread, and have a picture of 7mm Penna in the OP. I looked at their sizes and velocities, etc.

Metallic firearm cartridges are a very mature technology, have been for some time. OP doesn't even understand what it is about 6mm, 6.5mm and 7mm caliber rifles that makes them such a good balance for hunting and target use. I hinted at that, but instead of asking, he just continues obstinately down the same path, believing he has some revolutionary idea, seemingly unaware that there have been numerous cartridges in the class of his proposed which are obsolete for a good reason.

I do, in fact, understand that what makes ~6.8mm rifle cartridges so effective is the high velocity combined with superior sectional densities and ballistic coefficients; and yes, at slower velocities, they won't be nearly as effective. But, they still punch a bigger hole than say, .22WMR or .25 ACP...

I still think my original idea would've been a good one, provided one could get enough powder in the case to launch it fast enough, and without increasing the pressures to +40K psi.
But I've been shown that neither is technically possible.

There are a few reasons .25 ACP & .32 ACP have managed to hang in there, firm entrenchment in the market with myriad tiny guns so chambered, many of them very well made and aesthetically pleasing, being the most salient.

Yes. They're legacy cartridges with a lot of momentum. I figured, with new powder technologies, a superior caliber could be made intermediate to those two, no longer than a 9mmx19, without obscene chamber pressures and with more power. I guess not.

 

[Dibbs]

Modern cartridge and firearms development has been an evolution, of sorts, where many
cartridges, calibers, and designs have fallen to the wayside to what's popular. I'm going to
step out on a limb here, and propose that perhaps the .380 ACP (9MM X 17MM) is, at this point
in time, the pinnacle of the combination of performance and compactness. Not only is the round very
efficient, manufacturers embrace the caliber, by specifically fabricating compact pistols dedicated
to concealed carry.

But I don't have a dog in this fight, because I don't own any 380s. My personal preferences
lean to 32ACP, and 9mm Luger. Which shows the "OTOH" side of the coin, individual choice.

One of the things which make both 10MM and 5.7X28MM standouts, today, is they have garnered
attention for their unique ballistics. If you are going to have any success with a 6.8MM round, it's going to
have to have outstanding and unique ballistics of it's own, as it faces, to say the least, stiff competition.

What you have to do is create a round which not only is popular with people, but will also catch on with
manufacturers, the way the .380 ACP & 10MM did. Otherwise, you're looking at an awful lot of trouble, for a
caliber which would only be a flash in the pan.

 

[joneb]

Maybe .32 Super is the way to go

Maybe, the issue I have with smaller calibers is you need a lot of velocity to be effective, this means OUCH MY EARS HURT.
The 17 WSM rimfire got me thinking, why not a 5mm and .22cal super mag or maybe a 25 cal.
Most wildcat cartridges are more successful when a bullet already exists. Your 6.8 cal idea would require a new bullet design and construction for the target velocity.

 

[kBob]

7.65 French

-kBob

 

[6.8KT]

7.65 French

-kBob

Yeah I was looking at that one, and one other, as sort of ideal .32 Super-type cartridges for a pocket pistol


Basically, it would allow for one more bullet in the mag in a P3AT/LCP sized gun, which is a marginal step up I guess...

 

[tactikel]

I would absolutely buy it. But would prefer a .32 locked breech magnum (NOT a Naa). Less than 9 oz , 7 rounds of jhp at 1000 fps+. Give us a.32 acp .10" longer and @ 32 psi (.30 Mauser, . 30 Luger) and I will buy 5, me , wife, daughters, and sils.

 

[WestKentucky]

Tokarev, 30 luger, 32 French long... I'm sure there are others...

Oh yeah, 32naa, 25naa...

 

[Jim Watson]

I see no advantage to a bottleneck.
The .32 Froggie is interesting, but not interesting enough for anybody but the French to use, and that only 1935-1950.

If you want to play with the OP's 6.8, the 5.7 FN case blown out straight and trimmed to fit a pocket pistol magazine would be a place to start.

 

[6.8KT]

I would absolutely buy it. But would prefer a .32 locked breech magnum (NOT a Naa). Less than 9 oz , 7 rounds of jhp at 1000 fps+. Give us a.32 acp .10" longer and @ 32 psi (.30 Mauser, . 30 Luger) and I will buy 5, me , wife, daughters, and sils.

So basically, exactly the two rounds I pictured in post #84 above.
The .32ACP is ~.32x17mm.
The 7.65mm Long is ~.32x20mm
The 7.65 Mannlicher is ~.32x21mm
...And those would fit 7+1 in a P3AT-sized gun. A gain of one round and with roughly equal energy to .380ACP.

The .30 Luger (7.65×21mm Parabellum), however, is akin to a .38 Super (a long 9mm) necked down to .32 -- which defeats the purpose because then we lose magazine capacity.
Same with Tokarev and Mauser except they're even longer, equal to a .22WMR in length.

I see no advantage to a bottleneck.
The .32 Froggie is interesting, but not interesting enough for anybody but the French to use, and that only 1935-1950.

If you want to play with the OP's 6.8, the 5.7 FN case blown out straight and trimmed to fit a pocket pistol magazine would be a place to start.

If you chop the 5.7x28mm just below the shoulder, you're at .32x23mm, the next step up from the Mannlicher (.32x21mm)

In sum, I think a lot of us agree that something between .32x20mm to .32x23mm would be the best compromise for small packaging, additional magazine capacity, no real loss of energy compared to .380, and better penetration while perhaps giving up some stopping power to the larger caliber.

 

[BigBlue 94]

32 NAA is such an underappreciated round. The old 60gr bullets would zip out the barrel faster than a 38 and with more punch than a 32. The bottleneck aids in feeding in autos too. Even my tiny guardian pistol will hold 6+1 single stack.

 

[Jim Watson]

If you chop the 5.7x28mm just below the shoulder, you're at .32x23mm, the next step up from the Mannlicher (.32x21mm)

The 5.7 is smaller in head diameter than the various .32s, I was thinking of it as a basis for your original 6.8xXX. It would have a bit of taper, but if blown out straight it might make a 7mm. I was looking at the .270 REN (.270 Hornet) as a basis.

 

[6.8KT]

Seems like the 5.7mm is actually a really long .32 necked down to an extra light .223 bullet.

In any case, they pretty much proved earlier in the thread that ~6.8mm wouldn't work within my length constraints. It would have to be at least as long as .22WMR, maybe longer, plus a longer barrel, to get the performance that people would demand.

At this point, I'm thinking the optimal cartridge will be something like .32x21mm with an overall length of <31mm -- provided that wouldn't be too long to fit in the grip of current 9mm-sized guns. The idea being that existing 9mm frames could be chambered in the new cartridge without having to alter their grip/mag dimensions too much.

So, we'd gain +1 capacity in a P3AT/LCP, maybe +3 or 4 in a Glock 19 -- which isn't the gain I was hoping for in my original idea. I still think it would be worth it for something like this to exist in the marketplace. People would buy it.

 

[Coal Dragger]

I don’t think it is a

*disclaimer* I am in no way affiliated with KT.

What do you guys think of this idea?
View attachment 821269

I don’t think it is a viable plan, and you have included factually incorrect information about 6.8mm SPC being adopted as an official service rifle cartridge.

For starters your ballistics projections are optimistic.

Then there’s marketability vs the development cost, and the hassle of getting a major ammunition manufacturer to tool up to make the round even if ballistics could be achieved at reasonable pressures.

I won’t get into Keltec’s QA/QC issues but the one’s I’ve seen left a lot to be desired in a gun I would trust as life saving equipment.

 

[Varminterror]

So, we'd gain +1 capacity in a P3AT/LCP, maybe +3 or 4 in a Glock 19

And still have poorer stopping power, regardless of arbitrary kinetic energy hurdles or velocity hurdles you’ve set for yourself, and all you’ve done is gain a couple rounds which can already be bought for these pistols - pistols which shoot existing, common, inexpensive, easily sourced, better stopping power cartridges - by adding extended mags or base plates... the horse is dead, accept the fact you’re not gonna win the derby on this one...

 

[481]

After running the proposed .277-inch, 85-grain FMJ @ 1,000 fps design through the MacPherson and Schwartz bullet penetration models to predict its maximum penetration depth and its dissipation of KE to depth of 15cm for use in the US Army BRL's probability of incapacitation equation, the proposed design would offer tremendous straight line penetration depth and nominal probability of incapacitation.

The MacPherson bullet penetration model predicts 31.18 inches of penetration and the Schwartz bullet penetration model predicts 30.92 inches of penetration. The BRL-predicted incapacitation (for a single fired shot) is 53.77%.

Assuming that the proposed design is meant to compete against the very popular (these days) 3'' - 3.5'' barreled .380 semi-auto pistol loaded with a (0.355'') 95-grain FMJ @ 900 fps as a conservative baseline, predicted penetration is 18.83'' (Schwartz) and 20.13'' (MacPherson) with a BRL-predicted incapacitation (for a single fired shot) of 56.57% compared to the above example.

Not sure that an extra round or two is worth the trouble when it struggles to ''keep pace'' with .380 ball.

 

[6.8KT]

And still have poorer stopping power

I don't know. Maybe but maybe not. Look at the numbers for the the Mannlicher and Longue above. They have case lengths of 20 and 21, and throw ~80 grain bullets at 1,100fps.
So, with more modern powders in a case 22mm long -- maybe we could get north of 1,200fps; or up the projectile weight to 90gr at 1,100fps+.
This would be exceeding typical .380 energy, albeit in a slightly smaller diameter... but that would mean better penetration, and maybe more reliable expansion at the higher velocities.

by adding extended mags or base plates...

Which make the pistol that much less pocketable.

, pistols which shoot existing, common, inexpensive, easily sourced, better stopping power cartridges

I acknowledged that in my opening remarks -- that 90% of the battle is the logistics of a new cartridge for which little or nothing currently exists.

My goal is/was just that other 10% -- coming up with a good idea and filling a niche.

 

[6.8KT]

After running the proposed .277-inch, 85-grain FMJ @ 1,000 fps design through the MacPherson and Schwartz bullet penetration models to predict its maximum penetration depth and its dissipation of KE to depth of 15cm for use in the US Army BRL's probability of incapacitation equation, the proposed deign would offer tremendous straight line penetration depth and nominal probability of incapacitation.

The MacPherson bullet penetration model predicts 31.18 inches of penetration and the Schwartz bullet penetration model predicts 30.92 inches of penetration. The BRL-predicted incapacitation (for a single fired shot) is 53.77%.

Assuming that the proposed design is meant to compete against the very popular (these days) 3'' 3.5'' barreled .380 semi-auto pistol loaded with a (0.355'') 95-grain FMJ @ 900 fps as a conservative baseline, predicted penetration is 18.83'' (Schwartz) and 20.13'' (MacPherson) with a BRL-predicted incapacitation (for a single fired shot) of 56.57% compared to the above example.

Not sure that an extra round or two is worth the trouble when it struggles to ''keep pace'' with .380 ball.

Wow. Thanks for that. Who remembers when I estimated a ~50% one-shot stop probability on page 1?

Well, we established that 6.8mm straight-walled wouldn't work for other reasons -- namely case capacity.
Now I've moved on to .32x21mm or .32x22mm ... I'm thinking 85-90gr at 1,150fps (although that's getting up in the "high pressure/blast/recoil" zone)... Would you run the numbers on that?

 

[481]

Wow. Thanks for that. Who remembers when I estimated a ~50% one-shot stop probability on page 1?

Yeah, good guess. Go grab a PowerBall ticket for yourself tomorrow. Maybe it's your lucky day!

Well, we established that 6.8mm straight-walled wouldn't work for other reasons -- namely case capacity.
Now I've moved on to .32x21mm or .32x22mm ... I'm thinking 85-90gr at 1,150fps (although that's getting up in the "high pressure/blast/recoil" zone)... Would you run the numbers on that?

Sure.

For a 0.3125''-diameter 90-grain FMJ @ 1,150 fps:
Schwartz predicted penetration depth is 27.22 inches.
MacPherson predicted penetration depth is 27.93 inches.
US BRL Incapacitation Probability (for one shot) is 61.66%.

Using a 9mm (0.355'') 115-grain FMJ @ 1,155 fps for the sake of comparison, we get:
Schwartz predicted penetration depth is 26.49 inches.
MacPherson predicted penetration depth is 28.39 inches.
US BRL Incapacitation Probability (for one shot) is 65.97%.

 

[6.8KT]

Yeah, good guess. Go grab a PowerBall ticket for yourself tomorrow. Maybe it's your lucky day!

I actually did put some thought into it though. I looked at all the handgun one-shot stop numbers and surmised my hypothetical round would be about like a .38 Special FMJ.

Sure.

For a 0.3125''-diameter 90-grain FMJ @ 1,150 fps:
Schwartz predicted penetration depth is 27.22 inches.
MacPherson predicted penetration depth is 27.93 inches.
US BRL Incapacitation Probability (for one shot) is 61.66%.

Using a 9mm (0.355'') 115-grain FMJ @ 1,155 fps for the sake of comparison, we get:
Schwartz predicted penetration depth is 26.49 inches.
MacPherson predicted penetration depth is 28.39 inches.
US BRL Incapacitation Probability (for one shot) is 65.97%.

Outstanding. See now we're getting somewhere. We're nearly matching 9mm numbers with less recoil and the capacity of .32ACP.

 

[481]

I actually did put some thought into it though. I looked at all the handgun one-shot stop numbers and surmised my hypothetical round would be about like a .38 Special FMJ.

I am sure that you did. Didn't mean to imply that you hadn't thought about it.

Outstanding. See now we're getting somewhere. We're nearly matching 9mm numbers with less recoil and the capacity of .32ACP.

Well, maybe. You still need to produce a center fire pistol cartridge with the correct internal design/dimensions that can support the performance you are suggesting. Not saying that it cannot be done, but that that task is a big one, not to be taken lightly.

Then there's getting an ammunition manufacturer to support and produce it and a firearm manufacturer to chamber it in their firearm. That's an awfully tall order these days especially for a smaller 'low-power' caliber like that with no real JHP options at this time.

 

[6.8KT]

I am sure that you did. Didn't mean to imply that you hadn't thought about it.



Well, maybe. You still need to produce a center fire pistol cartridge with the correct internal design/dimensions that can support the performance you are suggesting. Not saying that it cannot be done, but that that task is a big one, not to be taken lightly.

Then there's getting an ammunition manufacturer to support and produce it and a firearm manufacturer to chamber it in their firearm. That's an awfully tall order these days especially for a smaller 'low-power' caliber like that with no real JHP options at this time.

You're right and I totally get that. The thing is, I've been a --- how do I put this -- a 'keyboard shooter --' for a long time. I've read so much about firearms over the years, looked at so many offerings from all the retailers online. But I almost never go to the range. LOL! I am a good shot though.

My point is, after 15 years of reading thousands of peoples' opinions in forums and articles and what not... Everyone seems to be faced with the same conundrum. They want capacity and stopping power with relatively little recoil in a small package.

So a lot people kind of waffle back and forth between .32ACP, .380ACP, 9mm, .38 Special... and many tend to end up just carrying a little P32 or LCP after realizing they won't faithfully carry anything else. This tells me there is a huge demand out there for something that can bridge the gap between tiny & weak and too big and too little capacity. (Edit: The P365 made a good effort at this, hence its enormous popularity last year.)

Ergo... if the gun/ammo manufacturers make this, the people will come [and buy it].