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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.
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". 

alexsoddy

From: alexsoddy

9-Aug

QuintusO said:

You're effectively describing the 5.8x42mm Chinese.

The 5.8x42 Chinese has a COAL of only 2.3 inches (vs 2.401 inches) and a case head diameter of 0.41 inches (vs 0.422 inches). IMO, it is a little different from the 5.8x42mm Chinese.

QuintusO

From: QuintusO

9-Aug

The DBP-88 sniper round has a COAL of 2.404". Almost identical.

NealB4Wilson

From: NealB4Wilson

9-Aug

Can you explain what a poly cap is and where the neck is on the case? Cheers. Also Nath is your forum still running competitions or are you guys mainly active on discord?

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