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True Velocity polymer case ammo   Ammunition <20mm

Started 17/11/17 by gatnerd; 12070 views.
autogun

From: autogun

17/9/20

EmericD said:

You mean, just like the Mle1898D bullet with a 8.15 mm shank riding in a 8.3 mm bore? That's one option, for sure, but you're still stuck with the very short ogive length of existing military cartridge.

Sure - but I was only trying to solve one potential problem without needing to alter the guns: the weakness of thin polymer necks. I wonder how the 7.62mm TV holds up when being hammered through a high-rof MG?

JPeelen

From: JPeelen

17/9/20

You are of course correct regarding the short ogive length offered by existing military cartridges. They are from a time when nobody thought that small arms would ever have any important role in combat again.  

But I cannot resist to remark that the 6.5x55 Swedish/Norwegian of 1894 offers 25 mm ogive length, compared to the "big" 23 mm of the new wonder cartridge 6.5 Creedmoor. Pity, that Norwegians and Swedes gave up their superior cartridge (sectional density)  for standardizing on 7.62 mm NATO, only to find out that 6.5 mm is now viewed as respresenting the future. 

  • Edited 17 September 2020 17:09  by  JPeelen
Red7272

From: Red7272

17/9/20

JPeelen said:

But I cannot resist to remark that the 6.5x55 Swedish/Norwegian of 1894 offers 25 mm ogive length, compared to the "big" 23 mm of the new wonder cartridge 6.5 Creedmoor. Pity, that Norwegians and Swedes gave up their superior cartridge (sectional density)  for standardizing on 7.62 mm NATO, only to find out that 6.5 mm is now viewed as respresenting the future. 

That was a Mauser thing after the 7.65x54. Everything from Mauser had 25 mm for the ogive. The US in their wisdom reduced it on the 30-03/6 and no one else thought it was a good idea at the time. 

nincomp

From: nincomp

17/9/20

Red7272 said...

Short necks are no different to long necks. The longer necks are just mechanically stronger and support the projectile better.

From what I could infer from the "stay out of the propellant" articles, the concern is that the turbulence of the combusting powder at the base of the bullet could effect the initial engraving into the rifling.  None of the articles specified whether the concern was simply bullet alignment or some other evil caused by propellant turbulence on the unprotected bullet base. (Wow! that almost sounds off-color :0  )

As for metallic case designs with the neck within the backwards necks.  Yes, I can see any number of problems when put into mass production.  It still would not surprise me if it had been tried and become one of those ratholes into which money was poured.  There is a big difference between having an IDEA and having A GOOD IDEA. ;)

 

 

nincomp

From: nincomp

17/9/20

Red7272 said...

Everything from Mauser had 25 mm for the ogive. The US in their wisdom reduced it on the 30-03/6 and no one else thought it was a good idea at the time. 

Yet another example of the difference between an IDEA and a GOOD IDEA.

QuintusO

From: QuintusO

18/9/20

You guys know all those decisions predated not just modern understanding, but really any comprehensive understanding of supersonic aerodynamics, right?

Different countries had different levels of (often secret) expertise in this at the time (the French understood it better than anyone else at least until the German wind tunnels arrived), but it's unreasonable to take it for granted that they "should have known" longer ogives would be better.

Only a few years prior to .30-06 (which really had its COAL set by .30-03, not by any aerodynamic principles) the French with their heights of understanding thought that the lowest drag ogive possible was a 2 caliber long tangent, based on atomic newtonian principles. The modeling available wasn't just bad, it was atrocious. The only way to optimize was to just do a ton of testing, but at the time that was EXTREMELY difficult. You can't see the bullets in flight, and the only way to measure retained energy is kinetically (how far does the pendulum move? Try hitting it at 1KM). Add to that their poor understanding of bullet stability and it's a mess. Not everyone figured it out. Certainly not the American Ordnance system, which before WWII was so impoverished it routinely outsourced almost all development to the private sector.

EmericD

From: EmericD

19/9/20

Only a few years prior to .30-06 (which really had its COAL set by .30-03, not by any aerodynamic principles) the French with their heights of understanding thought that the lowest drag ogive possible was a 2 caliber long tangent, based on atomic newtonian principles. 

Depends on what you call "a few years prior".

In France, nearly all the work on modern bullets was done between 1893 & 1896, and i7 bullet form factor as low as 0.82 were achieved at this time (and they had access to better instruments than only ballistic pendulum, electricity was known at this time).

So, 7 years before the adoption of the .30-03 everything was known (but kept secret), so ok let's say that the .30-03 and the .30-06 were just a bad timing...

The USA produced the Mle1898D bullet during WWII, and were perfectly aware of its ballistic advantage. By 1917, they did know that the shape of the Mle1906 bullet was not as good as it was supposed to be, so they copied the Swiss GP11 to make the .30 M1. During the '20s, when the "impoverished" US ordnance developped the .276 Pedersen, the bullet shape was following the best recipe known at this time.

They reverted to the Mle1906 shape for the .30 M2 excatly because the M1 had too much range, and not enough drag...

During the development of the M59 bullet, the US did known that better shapes were available because they used a secant ogive instead of a tangent ogive, but it was a very short one and didn't even cared to use all the space available. They selected a 1.8 calibre secant ogive when they have space for a 2.5 calibres ogive.

During the production of the .223 Remington, they did know that the 5.5 radius ogive used by Remington to load the cartridge was very inferior to the Sierra bullet used during development.

So, did they know that better shapes were available, I think the answer is "yes".

Did they cared? Not really.

QuintusO

From: QuintusO

19/9/20

EmericD said:

Depends on what you call "a few years prior". In France, nearly all the work on modern bullets was done between 1893 & 1896, and i7 bullet form factor as low as 0.82 were achieved at this time (and they had access to better instruments than only ballistic pendulum, electricity was known at this time). So, 7 years before the adoption of the .30-03 everything was known (but kept secret), so ok let's say that the .30-03 and the .30-06 were just a bad timing...

Correct, but these would have been secret for quite some time, correct? The US had no such ballistic program during this period.

 

EmericD said:

The USA produced the Mle1898D bullet during WWII, and were perfectly aware of its ballistic advantage. By 1917, they did know that the shape of the Mle1906 bullet was not as good as it was supposed to be, so they copied the Swiss GP11 to make the .30 M1. During the '20s, when the "impoverished" US ordnance developped the .276 Pedersen, the bullet shape was following the best recipe known at this time.

Correct, and it really confuses the heck out of me why the projectile shape for .276 Pedersen wasn't inherited by the .30 T65 program. I honestly have no answer to this, they simply went back to the M1906 shape in 1944 for seemingly no reason and then they kind of half-assed a secant ogive in there last minute.

EmericD said:

During the production of the .223 Remington, they did know that the 5.5 radius ogive used by Remington to load the cartridge was very inferior to the Sierra bullet used during development.

The .222 Remington Special was really a crash program. The people designing it (Stoner, etc) had never designed a small arms round before and were using what they knew. Should more effort have been put in? Sure. In fact, I demonstrated casually that they could have had an 0.73 i7 ogive at the time using only features present in extant bullets in the early 1950s.

EmericD said:

So, did they know that better shapes were available, I think the answer is "yes". Did they cared? Not really.

When I said they didn't know, I meant specifically during the development of the .30 M1906. Anytime after 1925? Yes, they knew, and it's extremely frustrating that they didn't seem to care.

Farmplinker

From: Farmplinker

19/9/20

I would blame the NRA. As long as the bullet was good enough for target shooting, why bother with further development? Especially if it results in higher ammo costs.

EmericD

From: EmericD

19/9/20

QuintusO said:

When I said they didn't know, I meant specifically during the development of the .30 M1906. Anytime after 1925? Yes, they knew, and it's extremely frustrating that they didn't seem to care.

You're right for the Mle1906, and I extended the discussion too fast.

I agree that reducing the ogive height from 25 mm down to 23 mm in 1906, while a move in the wrong direction, can't be regarded as a bad decision at this time.

Further reducing the ogive height from 23 mm to 20 mm for the T65 cartridge, while at the same time focusing on bullet penetration up to 1800 m, was really a bad move.

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