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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, particularly in larger calibres (12.7+mm).

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Exploring The Design Space   Ammunition <20mm

Started 25/7/15 by NathanielF; 99559 views.
QuintusO

From: QuintusO

8-Aug

R1K1M said:

Different topic: I was talking with idiot/Derpk-74 (M-100) over in the combined defense discord, and he claimed that nowadays you can design a 6mm cartridge with the same or better performance than 7.62 if you use modern high pressure technologies (poly case etc.pp.). He cited 6mm unified as an example how you could design it. However, that is fired from a 720mm barrel, which is a lot compared to the 550-650mm typical 7.62 MGs/Sniper Rifles have. When designing a modern replacement for the 7.62 round using NGSW technolgies, how would your favourite look like ? Can it really be done in 6mm without running into some weird issues ?

Depends what you mean by "7.62 performance". If, for example, what you mean is just drop and drift and energy at 1km, then you could have done this with a 6mm round in 1920.

If you check this thread you can see many of the 7.62 replacements I've worked on. Exactly what form that should take depends entirely on what combination of roles you expect it to fill.

Farmplinker

From: Farmplinker

8-Aug

Obviously, we want a 1500 meter DMR/GPMG cartridge that also works for room clearing. Out of a 10.5 barrel. That doesn't need a suppressor to be hearing safe. Needs to penetrate Level IV+ plates at a minimum of 600 meters obviously. Oh, and can be produced cheaper than M855A1 would really, really be nice. While fitting in an M4A1.

Sound about right?;-)

QuintusO

From: QuintusO

8-Aug

Picatinny: You're hired!

alexsoddy

From: alexsoddy

9-Aug

Could you please provide other specifications for the 0.237 Antidote like case length , overall length, case taper, shoulder angle, rim thickness etc. ?

It is very attractive as a general purpose round due to its case taper.

Gripen287

From: Gripen287

9-Aug

Case length is 1.85", COAL is 2.8", case taper is .5 degrees, shoulder angle is 25 degrees, and rim thickness is 0.06". 

Other relevant information can be found here:

https://drive.google.com/drive/folders/1b_85r_UF061OVW-E4OfzRm-Eg0YexDye?usp=sharing

and here, including info for the Mk2 design:

 http://sturgeonshouse.ipbhost.com/topic/1883-mini-competition-sioux-scout-rifle-caliber/

QuintusO

From: QuintusO

9-Aug

Notably, the case taper is identical to 5.56mm.

alexsoddy

From: alexsoddy

9-Aug

Thank you @Gripen287 .

I have a fundamental question. Is it possible to scale up cartridges ? (i.e. increase the size while retaining the shape of both the case and the bullet)

I wonder if it would be possible to scale up the 5.45 x 39 cartridge by 7%.

The case head diameter would then equal that of the 6.8 SPC. The bullet diameter would increase to 0.236 inches. The COAL would increase to 2.401 inches. The case length would increase to 1.677 inches. It would not be compatible with AR-15 rifles though.

QuintusO

From: QuintusO

9-Aug

alexsoddy said:

I have a fundamental question. Is it possible to scale up cartridges ? (i.e. increase the size while retaining the shape of both the case and the bullet)

Yes, I do this all the time, especially with bullets. It is a shortcut where if I have arrived at a good design, I can just scale it up and down to different calibers to find the ideal application for it. I do it with cases, as well, but less often.

alexsoddy said:

I wonder if it would be possible to scale up the 5.45 x 39 cartridge by 7%.

Yes. I did this years ago. I called it the 6x44mm:



It was a 5.45x39 scaled up by 10%, to use standard 0.243" projectiles. The projectile was the 77gr taken from the 6mm Unified. I forget what the muzzle velocity was, probably 2,700-2,900 ft/s. I decided to increase case length by 2mm to improve performance and then dropped the project. However, several times I have come back to similar studies.
 

alexsoddy said:

The case head diameter would then equal that of the 6.8 SPC. The bullet diameter would increase to 0.236 inches. The COAL would increase to 2.401 inches. The case length would increase to 1.677 inches. It would not be compatible with AR-15 rifles though.

You're effectively describing the 5.8x42mm Chinese.

Gripen287

From: Gripen287

9-Aug

.230 Theriac is also similar to what you're describing. It's a 77 grain EPR with a steel penetrator, steel core, and a .236" integral driving band diameter. The case has a .42" rim diameter and a 1.685" stainless steel case with polymer cap. COAL is 2.5". 

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