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anti material rifle not dead   General Military Discussion

Started 29/9/21 by Mr. T (MrT4); 11416 views.
gatnerd

From: gatnerd

3/10/21

EmericD said:

The 12.7x108 mm API B-32 (~52 mm long steel core) is nearly delivering identical AP capability as the 12.7x99 mm APEI NM140. The 12.7x99 mm PPI (~54 mm long steel core) is mid-way between the NM140 and the NM173 / NM185. The velocity to defeat 50% of the time a 21 mm RHA plate is around: 670 m/s for the 12.7 mm B-32, 660 m/s for the 12.7 mm NM140, 595 m/s for the 12.7 mm PPI, 545 m/s for the 12.7 mm NM173 / NM185.  The 14.5x114 mm API B-32 is using a 63.3 mm long, high hardness, steel core, the capability is much better than the NM173 (if the gun barrel is long enough).

Great info as always, thank you. 

Also quite the revelation. I hadn't realized 12.7 was so much more capable then .50 bmg (I had thought it to be a 9x17 vs 9x18 type of difference). 

Likewise, your data shows how penetrator length can really effect penetration, and how a long enough steel penetrator can mitigate the need to employ tungsten. 

In terms of the .50 bmg replacement we were discussing in the other thread, what would be the minimum practical caliber to have a 52-54mm PPI style penetrator? 

And has there been any study on penetrator shape as it relates to penetration? The PPI and others penetrators are rather blunt and sturdy points that looks like they would be fairly durable on impact. 

Would a finer, VLDish pointy penetrator tip effect its ability to penetrate? I wonder whether the finer point would be more susceptible to deforming/shattering on impact, reducing the efficacy of a "VLD-AP" PPI type projectile? If so that would kill off the hopes for a .375-416 style .50 replacement, as they rely so heavily on a VLD profile. 

EmericD

From: EmericD

4/10/21

gatnerd said:

Also quite the revelation. I hadn't realized 12.7 was so much more capable then .50 bmg (I had thought it to be a 9x17 vs 9x18 type of difference). 

The .50" M33 ball is just the "companion load" of the M8 API that was developped mainly for air-to-air use during WWII, hence the focus on the highest velocity, BC was less a factor at high altitude. Better loads for ground-to-ground exist, but the M8/M33 family seems to be good enough.

The NM140 is a multipurpose round, the penetration is just one part of the round capability portfolio.

gatnerd said:

In terms of the .50 bmg replacement we were discussing in the other thread, what would be the minimum practical caliber to have a 52-54mm PPI style penetrator?

.408" seems a good starting point, I've been told that the .375 EnABELR 400 gr API was also very capable, but anyway you will lack the HE payload of the NM140. That's why I think that the best bet for a .50 BMG replacement is necking up the case to 15-16 mm to accommodate for a bigger payload, and running the round at 350-380 MPa instead of the current 280-290 MPa.

gatnerd said:

Would a finer, VLDish pointy penetrator tip effect its ability to penetrate? I wonder whether the finer point would be more susceptible to deforming/shattering on impact, reducing the efficacy of a "VLD-AP" PPI type projectile? If so that would kill off the hopes for a .375-416 style .50 replacement, as they rely so heavily on a VLD profile.

That was exactly what the company "Stiletto" was offering, very long & pointy WC core, and the penetration capability at 0° AoA was outstanding. I don't know what would the the effect of increasing the AoA compared with blunter design.

As a rule of thumb, you need a steel core ~60% longer to achieve the same penetration capability as a WC core against RHA or thin ceramic plate at 0° obliquity and impact velocity below 800-850 m/s, above that speed the steel core will shatter, reducing the capability.

gatnerd

From: gatnerd

4/10/21

In terms of a necked up .50 to 15-16mm, what do you think that would look like in terms of projectile weight and velocity?

Good to know that +60% steel to WC rule of thumb, thank you. Also interesting about not having the velocity too high. Is there an optimal steel alloy / hardness as well? I had thought something like S7 tool steel, which is an impact resistant alloy used in jackhammer bits and tactical breaching axes.

In terms of Stilletto, I rember a few years back TFB / Forum had a lot of scepticism for their penetration claims. Cool to hear they were the real deal, especially as it keeps the VLD-AP hopes alive.

EmericD

From: EmericD

7/10/21

gatnerd said:

In terms of a necked up .50 to 15-16mm, what do you think that would look like in terms of projectile weight and velocity?

If I take the drawing of the .50 BMG in order to make a neckless upgrade, the difference between L6 (138.43 mm) and L2 (83.3 mm) is 53.13 mm or 2.09".

If the projectile diameter is increased to .61", then we have ~3.4 caliber to account for the ogive length, which is more than enough to accomodate a very sleek profile, so let's use a 0.90 i7 FF which could be achieved even with a flat-base design.

The current BC of the M8/M33 family is 0.35, so that mean that we should aim for a 0.61" projectile with a minimum weight of 820 gr / 53.2 g, launched at a MV ~850 m/s.

gatnerd

From: gatnerd

7/10/21

The specs for your .61 sound excellent. Do you think it would be backwards compatible with current .50 bmg weapons?

In terms of down range performance, do you see the value of the .61 primarily in increasing penetration, or increasing incendiary payload?

If the projectile is of comparable length to a .50/ .50 neckess, would the increased penetrator mass of the .61 still increase penetration even if the cores are the same length?

JPeelen

From: JPeelen

7/10/21

I cannot help but repeat my view that a cartridge according to requirements should be chosen first.

After that, an "optimal"  (compromise of conflicting design goals) weapon should be designed around it.

In my view, it is usually overlooked that, in the long run, ammunition is the expensive item, not the weapon. The backwards compatibilty issue looks at a single weapon, more or less from the perspective similar to the private owner. He does not shoot enough to wear out the gun. He enjoys an unlimited life-cycle.  

But in military use, guns have to be reconditioned and even replaced on a routine basis. Life-cycle is really limited. We live in an environment with an industrial base which is most economical at mass production, not mimicking gunmaker style.    

Using backwards compatibility as the goal is by no means as cheap as it looks on first sight. At the same time it severely limits possibilities of achieving up to date ballistics.         

EmericD

From: EmericD

7/10/21

JPeelen said:

But in military use, guns have to be reconditioned and even replaced on a routine basis. Life-cycle is really limited. We live in an environment with an industrial base which is most economical at mass production, not mimicking gunmaker style.    

I agree for most of the weapons, but the M2HB is a special piece of hardware.

The French army is still using ~10,000 M2HB manufactured before 1944, and we used then heavily since the war in Indochina.

stancrist

From: stancrist

7/10/21

JPeelen said:

I cannot help but repeat my view that a cartridge according to requirements should be chosen first. After that, an "optimal"  (compromise of conflicting design goals) weapon should be designed around it.

I disagree.  In my view, the weapon and cartridge must be designed together as a system.

To design one without regard to the other, seems unlikely to produce the optimal results.

JPeelen said:

Using backwards compatibility as the goal is by no means as cheap as it looks on first sight. At the same time it severely limits possibilities of achieving up to date ballistics.

Normally I would agree, because for the last 100-plus years, backwards compatibility with existing weapons has rarely -- if ever -- been a real concern, let alone a military requirement.

In the mid-19th century some armies adopted new metallic cartridges to upgrade old muzzleloaders, but since then the practice has been to acquire new weapons for any new cartridge.

However, Emeric presents a good argument that the M2 Browning may be a special case, a unique exception to the rule.

gatnerd

From: gatnerd

7/10/21

"The French army is still using ~10,000 M2HB manufactured before 1944, and we used then heavily since the war in Indochina."

Thats awesome.

The US has had similar results - there was a discovery of one made in 1933 that was still in service and operating perfectly:

https://www.firearmsnews.com/editorial/oldest-m2-browning-50-caliber-mg-still-in-service/383060

I recall reading numerous anecdotal reports of guys in Iraq whose M2's receivers were marked 'General Motors' and 'Frigidaire' indicating WW2 manufacture.

The design seems to be so successful that it has essentially killed off any competition. As far as I can tell the only alternative .50 bmg machine gun is the STK50 from singapore?

https://www.stengg.com/media/30308/50mg-brochure.pdf

gatnerd

From: gatnerd

7/10/21

JPeelen said:

I cannot help but repeat my view that a cartridge according to requirements should be chosen first. After that, an "optimal"  (compromise of conflicting design goals) weapon should be designed around it.

Thats certainly the ideal...

The question is whether we will actually see that occur. Theres been talk of a desire for a 'GPC' type intermediary cartridge for 15+ years, yet theres yet to be any manufacturer step up to the plate and create an intermediary sized weapon. Perhaps the LWRC SIX8 as an exception. 

Meanwhile the cartridge we're seeing genuinely take off a bit militarily as a 5.56/7.62 alternative is 6.5 Creedmoor (and .260 Remington per Emeric for French SF.) The reason is that it offers enhanced ballistics with a simple barrel change. 

A superior round, but requiring a brand new series of assault rifles and LMG's to be developed to fire it, would likely still be a topic of debate on internet forums...

For a .50 replacement, the prospects of a 'perfect' cartridge are even grimmer. A rifle is complex, but at the end of the day, it's a rifle, which most small arms manufacturers are capable of designing and manufacturing. Whereas a Machine Gun is both much more complex and requires far more in terms of testing and long terms durability, and far fewer small arms companies are capable/familiar with producing them. Much less producing a HMG that could compete with the prolific, legendary, and beloved M2... that would be a risky R&D venture to undertake without a gov't contract behind it. And until the new weapon was developed, the new cartridge design could not be tested. 

Whereas if '.61 Emeric' is backwards compatible with .50 bmg weapons, that bad boy could be tested within a year and with a fraction of the R&D budget. Get a firearms company or even machine shop to turn a new .61 M2 barrel, neck up some .50 BMG brass, and lathe turn some brass .61 solids, and you're in testing mode. Thats of course a bit flipant in terms of the work involved, but its certainly a much easier prospect than creating a new cartridge brass, new bullet, and new automatic weapon all at once. 

The last issue is one of requirements. Since the .50 BMG/M2 is a sort of ballistic 'Swiss army knife' (never the perfect tool for the job, but a tool that works for many jobs in the field) it's hard to pin down what the requirement would be to optimize the cartridge for. Is the goal a lighter cartridge/weapon with comparable penetration to .50 API? Is the goal better supersonic range than .50 API? Better incindiary effect? More penetration? More power then .50 BMG but with smaller weapon than 20mm cannon? etc. 

In that light, ".61E" is potentially promising. Get a more powerful / more API round than current .50bmg, while keeping polymer cartridge weight comparable to current .50 bmg brass, and the ability to be used in legacy weapons / future .50 sized weapons and mounts. 

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