gatnerd

Military Guns and Ammunition

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This is intended for people interested in the subject of military guns and their ammunition, with emphasis on automatic weapons.

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Neckless ammo   Ammunition <20mm

Started 20/8/21 by EmericD; 41935 views.
QuintusO

From: QuintusO

20/8/21

If you eventually want to fire these from standard 5.56 chambers, what's your plan to address the long bullet jump? Some sort of weird neck extension?

QuintusO

From: QuintusO

20/8/21

I was quite put out that you chose to use the 1:7 twist when I recommended 1:6.5 or tighter, and then insisted it could not be a stability issue when it didn't shake out (it obviously was). I understand now why you used 1:7 (it seems you plan to use neckless cases in HK416Fs), although IIRC that wasn't really explained to me at the time.

Had communication been better, I could have sent you a VKO that I expected to work better with 1:7 from the start to verify the i7. But c'est la vie.

https://www.youtube.com/watch?v=1OeiYxdteTQ

QuintusO

From: QuintusO

20/8/21

And for the record, the VKO-Short is simming at about 0.84 i7, and fits standard 5.56 cases without issue.

  • Edited 20 August 2021 20:10  by  QuintusO
gatnerd

From: gatnerd

21/8/21

stancrist said:

I was thinking a VLD solid would be fine for military Ball ammo, but what would you do for VLD Tracer and AP.

One of the questions I've had for awhile and havent found an answer for is how Steel AP cores are manufactured.

Are they turned on a automatic lathe? Are they cast? Are they swaged/pressed? MIM?

If the cores are made on a lathe, then that would certainly allow very nice VLD AP projectiles. They could make a sort of 'AP EPR' that doesnt fragment, where the entire exposed ogive is lathe turned hardened steel, and then the base is jacketed. 

With other methods, I'm not sure if they could make one as fine. 

gatnerd

From: gatnerd

21/8/21

QuintusO said:

And for the record, the VKO-Short is simming at about 0.84 i7, and fits standard 5.56 cases without issue

That sounds very promising, and seems like it would also be of quite a bit of civilian interest in the US - not much available now for real VLD 5.56 loads. 

autogun

From: autogun

21/8/21

Gatnerd, could you check your PMs please?

stancrist

From: stancrist

21/8/21

gatnerd said:

One of the questions I've had for awhile and havent found an answer for is how Steel AP cores are manufactured.

Are they turned on a automatic lathe? Are they cast? Are they swaged/pressed? MIM?

If I ever read about how AP cores are made, I forgot it long ago.

Photos show what look like tool marks from lathe manufacture.

Perhaps Hackley Volume III has info on the production method?

EmericD

From: EmericD

21/8/21

gatnerd said:

Were the bullets brass or copper?  And what would a 6mm version look like in terms of weight / estimated BC?  Curious how the modern Balle D shape stacks up vs the 6mm Flatline. 

The bullets are made of a free machining copper alloy with low elongation and high mechanical resistance.

A 6 mm version would weight 81 gr, with a .234 G7 BC, significantly less than the 6 mm Flatline which is heavier, longer (31.6 mm vs. 29.3 mm), and with a better form factor.

Being shorter & lighter, the "D" version could be pushed at a higher MV...

Using the reloading tables for the 6 mm Flatline and the Powley computer, the 88 gr FL can achieve 3050 fps in a 28" barrel at 48 kCUP, which translates to 2790 fps (851 m/s) in a 16" barrel. The "D" would reach 2910 fps (887 m/s) in this same configuration.

The "D" would have a velocity "edge" over the Flatline for the first 600 m, "better" ToF up to 900 m, but slightly less energy (both loads would be very similar).

EmericD

From: EmericD

21/8/21

That's the problem when you try to "kill two birds with one stone", sometimes the stars are not aligned in a good way.

I still don't think that the "counter performance" of the 70 gr VKO was linked to the bullet stability, because after dealing with the launch AoA, the bullets flew well up to 2500 m. But maybe you want to point out that it could be linked with bullet angle of repose not being ~0°, and shorter twist could (sometimes) mitigate this problem (or not).

EmericD

From: EmericD

21/8/21

gatnerd said:

One of the questions I've had for awhile and havent found an answer for is how Steel AP cores are manufactured. Are they turned on a automatic lathe? Are they cast? Are they swaged/pressed? MIM?

Grinding machines, so don't expect tight manufacturing tolerance and fine geometry.

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