gatnerd

Military Guns and Ammunition

Hosted by gatnerd

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

  • 3339
    MEMBERS
  • 189798
    MESSAGES
  • 1
    POSTS TODAY

Discussions

NGSW Phase 2 Consolidation and info   Small Arms <20mm

Started 30/8/19 by gatnerd; 505524 views.
Guardsman26

From: Guardsman26

26-May

Stan, 

SOCOM isn't developing an EPR bullet in 6.5 mm, RDECOM already has as part of the previous SAAC study. It developed EPR bullets in 6 mm, 6.35 mm, 6.5 mm, 6.8 mm and 7 mm. I guess the technical design package would be amiable to any US military organisation that wanted it. My understanding is that SOCOM units deploying with 6.5 and 6 mm weapons have an EPR loading. 

Un-related to the above and thinking back to your 6 mm Optimum; if you were asked to realise a contemporary  today, how would you go about it or change it? 

stancrist

From: stancrist

26-May

Guardsman26 said:

SOCOM isn't developing an EPR bullet in 6.5 mm, RDECOM already has as part of the previous SAAC study. It developed EPR bullets in 6 mm, 6.35 mm, 6.5 mm, 6.8 mm and 7 mm. I guess the technical design package would be amiable to any US military organisation that wanted it.

Okay, that seems logical.

Guardsman26 said:

My understanding is that SOCOM units deploying with 6.5 and 6 mm weapons have an EPR loading. 

Very interesting.  A pity we can't get a photo of either EPR bullet.  

Guardsman26 said:

Un-related to the above and thinking back to your 6 mm Optimum; if you were asked to realise a contemporary  today, how would you go about it or change it?

Oh wow.  I figured the 6mm Optimum was a long dead subject, and have given it no thought for years.

When I came up with the idea, it was still the lead-core bullet era.  So an obvious update would be EPR.

Also, I'd assumed that -- as in the past -- completely new rifles and machine guns would be developed.

The current practice seems to be to restrict OAL of candidate cartridges to that of 5.56x45 and 7.62x51.

Since nobody seems interested in making rifles and machine guns for intermediate-length cartridges, perhaps lengthen the 6mm Optimum case and increase COL to 2.80 inches, or shorten the case and reduce COL to 2.26 inches?

gatnerd

From: gatnerd

26-May

“Titanium is much less dense than the steel and copper used in EPR bullets and sectional density is very important to BC“

It is less dense(~40% less then steel) but with EPR construction a couple ideas come to mind:

-Shorten the titanium tip by ~40% to increase the length of the copper slug, resulting in comparable weight to copper/steel EPR 

-Replace copper slug with Bismuth to increase weight to offset titanium weight loss

Either seems easier then trying to match the weight and form factor with a pyrotechnic spotter/tracer, as those compounds are super lightweight.

stancrist

From: stancrist

26-May

gatnerd said:

Replace copper slug with Bismuth to increase weight to offset titanium weight loss

That does not seem feasible.  Early in M855A1 development bismuth was used, but had problems that caused a change to copper.

gatnerd said:

Either seems easier then trying to match the weight and form factor with a pyrotechnic spotter/tracer, as those compounds are super lightweight.

M62A1 Tracer weighs the same as M80A1 Ball, which indicates that matching the bullet weights may not be overly difficult.

It seems like it would be difficult to match form factors, considering how different are the shapes of EPR and Tracer bullets.

stancrist

From: stancrist

27-May

The History Behind Sig Sauer's XM250

Jason St. John recounts the whole story behind Sig Sauer's XM250 at Sig Freedom Days May 6-8, 2022.

graylion

From: graylion

27-May

sorry, my BSmeter went off too loudly for me to watch that

EmericD

From: EmericD

27-May

Guardsman26 said:

Emeric, I am not a ballistician, but what do you estimate would be the chamber pressure of a 6-7 gram 6.5 mm bullet fired from a 6.5x49 mm Creedmoor cartridge at 3,000 fps / 914 mps?

The 264 INT (the child of the 264 USA) is pushing a 6.7 g EPR bullet at 3010 fps out of a 20" barrel (and 2850 fps from a 14.5"), while staying below 62 kpsi.

  • Edited 27 May 2022 14:35  by  EmericD
Guardsman26

From: Guardsman26

27-May

How interesting. I was not aware of this cartridge. Can you point me towards more technical information about it. 

I am going to contact you separately to discuss NGSW!!! 

gatnerd

From: gatnerd

27-May

Great picture! I’d also like to know more about the .264 INT, and how it compares to 6.5C.

nincomp

From: nincomp

27-May

Disassembly of SIG Spear.

  Note, the "PDQ" that is mentioned a couple of times is the aftermarket "PDQ ambidextroud-bolt release" that Karl has used in the WWSD (What Would Stoner Do) carbine.

https://youtu.be/hO4IKxECNzI?t=351

TOP