The Ultimate Combat Round

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Something like these? These were for a Mini-30 project and would have funtioned from a Pro-Mag 10 rd magazine. Velocities would have been similar to the standard 35 Remington using 357 Magnum bullets for defense and small game and 35 Rem bullets for deer and hogs.

From the left: Shortened 6.5 Carcano brass(new manufacter from Norma, .450 diameter, just a hair larger than 7.62x39), 35 Remington(.460 diameter), and 358 Win(.470 diameter).
 

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Similar to what I was thinking of, but the case for the .357 would be a straight-walled one, not necked.
Plus, it'd have a sabot.
 
Understood.:) I like what I've read here and I'm trying to get you guys to increase the case capacity by using the largest diameter case that will function from an AR mag. ;)

Grendel or shortened AR-10 mag.
SOCOM .471 bolt head.


Edit: My software has .30 saboted bullets in it from Remingtons old 55 gr .22 cal Accelerator 30-06 ammo. It also has one for the 30-30, I don't remember that loading. Tell me which case specs and barrel length and I can run it. No telling how accurate the data will be. I don't have any other diameter sabot loads but I can neck it up or down to .308 first. I can also change the weight of the .22 bullet.
 
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I'm not sure that we're too worried about keeping it AR compatible. This isn't the most realistic thread, if you've noticed. :D
Edit: My software has .30 saboted bullets in it from Remingtons old 55 gr .22 cal Accelerator 30-06 ammo. It also has one for the 30-30, I don't remember that loading. Tell me which case specs and barrel length and I can run it. No telling how accurate the data will be. I don't have any other diameter sabot loads but I can neck it up or down to .308 first. I can also change the weight of the .22 bullet.
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As I said earlier, it would just be a blown out 5.56. So a 9.6mm case head, 45mm length case... that's really it. 9mm sabot. 77- or 82-grain bullet in the sabot.
By the way, have you read the entire thread? It's a big read, but there's some neat stuff in it.
 
OAL 2.265" from a 20" barrel. I'll keep the pressures around 52,000 CUP. I'll use the same powders where possible.

5.56x45 straight .377 with .357 cal 110 grain Hornady XTP, 2970 using 33 gr N120.

With .357 cal 158 grain XTP, 2400 fps using 29 gr N120.

With .357 cal 180 grain XTP, 2200 fps using 25 gr AR2205.

Necked to .308 using the 55 gr Accelerator sabot, 3600 fps using 24 gr AR2205. A bit hard to believe. This is why I earlier said that I didn't know how good this data would be.

With the same sabot but changing the bullet weight to 75 gr, 3150 fps using 24 gr AR2205.

Trying to cross check this is with the Lyman 77 gr .308 cast bullet, 3200 fps using 29 gr N120. This bullet is too short so I had to use a 2.2" OAL. It's barely in the case at all which might explain the velocity.

Even though the Lyman bullet seems to cross check the data with the 75 gr.22 sabot load, I still have trouble believing the sabot data. Then again I'm certainly no expert.

I'd kept up on the thread up until a couple of months ago and I caught up by reading the rest before I posted today. I'd stopped reading because it looked to me like it was going into the theorertical. When I caught up today I was impressed on how those theoretical tangents had been discussed and discarded and everything came back around to present technologies. I agree, it is a good read.
 
I don't. The data seems to be okay. The weapon just went from pushing a .22 caliber bullet to pushing a .30 caliber bullet. A net gain of about 200 f/s is quite reasonable. Now, we just need a .357 caliber sabot. Think! Shooting an 82-grain Lapua Scenar-style bullet at 3000 f/s out of a 20-inch barrel! That's roughly 2800 f/s out of a 16-incher. You'll devastate anyone at any range.
 
The only available sabots that I know of. https://www.eabco.com/reload02.html I think that the .308 sabot is better for this case anyway due to the lack of taper in the narrow 5.56 case. Use the 6.5 Carcano or LARGER DIAMETER :D case and a 9mm sabot would work fine, if there is one. I once read of a sabot for 6mm bullets so I'm sure that someone can manufacture different caliber versions.

I agree with Tony Williams that a saboted bullet probably won't be accurate enough for long range. And if it's only a medium range load does the velocity gain offset the smaller bullet diameter?

The cartridge that I'm looking at should launch an .30 cal 155 AMAX at around 2500 fps. This should be devastating at civilian defensive ranges and will be a fine deer/hog load out to 300 yards with the 130 TSX or the 150s. There is something to gain with bullet diameter providing it has enough velocity for good bullet performance.
 
You and your big, fat cases...
The problem I have with them is weight. They're heavy. They actually have a better weight-to-volume ration, but they're physically heavy. I don't like to go over 10.5mm for a light assault rifle (5.56-6mms).
 
Mine is a civilian cartridge using civilian bullets. The .308 diameter is great for the huge range of available bullets.

For a military cartridge I'd neck it to 6.5mm. Call it a 6.5mm Lapua short.

That would lighten it up, well a little. :)
 
Mine is a civilian cartridge using civilian bullets. The .308 diameter is great for the huge range of available bullets.

For a military cartridge I'd neck it to 6.5mm. Call it a 6.5mm Lapua short.

That would lighten it up, well a little.
Click to expand...
Well, you just made 6.5 GunTech.
Besides, that's not a good caliber for a light assault rifle.
 
Kinda, except mine runs from an AR and AR mags. If THAT'S not a good assault rifle cartridge then I'll just step back out of this thread for a few more months. Enjoy.
 
Why abide by the silly Hague Convention? I don't think anyone still cares about that part of the HC anymore (maybe the Euros, but their boys aren't getting shot), so why keep it up?
Click to expand...

The obvious argument against not dropping the Hague Convention is that if we do, everyone else will, too. As a potential end recipient of ordnance in that sort of scenario, I'm not too keen on the idea.

As for the Europeans -- they've got guys in Afghanistan, Iraq, etc., depending on which nation(s) you mean. Even the quintessential stereotype of Europeans, the French, are almost as eager to stick their noses in 3rd World Hell Holes as we are, sometimes more so if they've got a history in a region.
 
Kinda, except mine runs from an AR and AR mags. If THAT'S not a good assault rifle cartridge then I'll just step back out of this thread for a few more months. Enjoy.
Click to expand...
Oh, it's fine for an assault rifle, just not a light one. I'm a rather all-out person. So, if I'm gonna go with a 6.5mm cartridge, I'm not really going to worry about the OAL of an M16, I'm gonna go longer, because I really need to.
I consider the AR to be a light assault rifle. The AK, though it has a shorter mag (because it operates on the big and slow theory) is a medium assault rifle. If the EM-2 had ever been adopted, it would have been a large assault rifle.
Do the Euros still have boys in Iraq (Afghanistan, I know). The Brits do, is there any other European country that's still in? Didn't Poland pull out? Besides, I don't see anyone we're fighting abiding by the HC anyway, so what difference does it make?
 
Besides, I don't see anyone we're fighting abiding by the HC anyway, so what difference does it make?
Click to expand...

The guys we're fighting don't abide by the HC in their conduct, but whoever they buy bullets from abides by it. When Russia, China, Iran, et al, start cranking out enhanced lethality, non-Hague compliant rounds (or maybe "more enhanced" is the better term, since everyone including us have been tweaking lethality within the FMJ framework for years), we'll start catching them coming back at us, too . . .
 
Hmmm...
That's a really good point...
Is there a way we can not be Hague compliant and still look like we're Hague compliant?
 
I wouldn't say that saboted bullets aren't accurate enough at long range - the Swedish Army adopted a saboted 7.62x51 round for their sniper rifle. The dispersion is greater than with full calibre rounds, but the thing has a ray-gun like trajectory which means that aiming is relatively simple, so the practical hit probability is higher than you might think.

We already do stretch the Hague Conventions to the limit. Apart from the specific ban on expanding bullets in the 1899 Convention, the 1907 Convention states that:

"In addition to the prohibitions provided by special Conventions, it is especially forbidden:…To employ arms, projectiles, or material calculated to cause unnecessary suffering"

This could well be taken to include fragmenting bullets. The only defence is that the bullets aren't designed to fragment, it just sort of happens.
 
The MV of the Steyr ACR was on the order of 1,200 m/s, so the sabot approach certainly does have its merits. Among other things, a drag stabilized projectile can have a BC that spin stabilized bullets can only dream of.
 
I have a triumphantly new idea for cheating the propellant pressure curve, improving ballistic coefficient, and generally making the wonderwaffen that we all need in our ever-expanding collections! It's uncouth, radical, and likely impractical, but it has the virtue of having already been tried, and not actually being my idea.


Extended Range Full Bore rifling seems to be all the rage these days in artillery. Why not scale it down to small-arms size?

No more engraving pressure means that the case crimp is less important to accuracy, and no more gas slipping by the bullet means less fouling.

What say ye?
 
I think that Wiki entry on ERFB shells is wrong. The stub fins on the ogive of the shell are there because the very long, fine point used to achieve the high ballistic coefficient needs some support, otherwise the shell would flop about in the barrel. The fins are bore-riders, not groove followers (I don't see how they could be the latter, as they are used in autoloading artillery which has no means of marrying up the fins with the grooves. And they are too thick anyway - stubs rather than fins). Obturation and connection with the rifling is achieved in the usual way with artillery shells, by a driving or rotating band near the base of the shell, which is forced into the rifling grooves as usual.

There have been some shells in the past which were designed to fit into rifling grooves; they were very specialised ultra-long range jobs like the WW1 Paris guns. And way back in the 19th century, some of the earliest forms of rifling had a couple of big grooves to which studs on the shells were mated up by hand. I think that WW2 was the last time that such ammo may have been used, though.
 
Glad to hear you chime in on this Tony!

Looking at the Denel information sheet on their ERFB carrier shells, I could see it either way:

http://www.denel.co.za/Landsystems/LS_ArtillerySysERFB.pdf

There's something near the base that looks a whole lot like a driving band, but it also doesn't appear to protrude as far as the fins/groove followers.

Edit:

D'oh! The document in question explicitly refers to a gilding metal driving band.

So what exactly makes these things special?
 
It's the shape. Compared with a conventional HE shell the very long, fine nose greatly reduces the aerodynamic drag and thereby significantly increases the range. Those stub fins also don't just support the nose in the bore; they also develop a small amount of lift to add further to the range. And these rounds often have a base-bleed unit screwed to the base, which reduces drag further.
 
Even without the base-bleed, Denel is claiming ranges with their 105mm pieces comparable or superior to other 155mm pieces.

Thank you for clearing up my misconception of how these things work.

Any reason why ERFB munitions could not be scaled down for use in rifle calibers?

and do you know how much was gained with the groove-following shells?
 
You have to be careful that you're comparing like with like: Denel's new 105mm gun uses a massive propellant charge to provide a very high muzzle velocity, which works together with new aerodynamic shell designs to provide a much longer range than other 105mm.

In a sense, ERFB is being applied to small-arms bullets. take a look at Hornady A-MAX and similar bullets designed for long-range sniping: they have very fine points and extremely high ballistic coefficients. They just haven't used stub fins.

I think that the use of splined, groove-following shells was made necessary by the extremely high pressures and velocities developed by such as the Paris guns. A conventional copper driving band would have been shredded and ripped off.
 
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