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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.

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For Your Amusement   General Army topics

Started 15/9/21 by stancrist; 15304 views.
stancrist

From: stancrist

26-Aug

I want to say the reason for switching from M2 Ball to M2 AP was for better barrier penetration, but I am not sure if I'm remembering correctly.

It's been well over 20 years since I read about it.  I think it was in Collector Grade's The '03 Era, if you want to check it and have access to a copy.*

*ETA:  My memory of where I read it may be faulty.  It might actually have been HWS Vol II.  See Msg 127 below.

  • Edited 26 August 2022 17:06  by  stancrist
EmericD

From: EmericD

26-Aug

stancrist said:

I want to say the reason for switching from M2 Ball to M2 AP was for better barrier penetration, but I am not sure if I'm remembering correctly.

I thought that the US ground forces started to use the APM2, after large stocks were made available by the decision of the "air force" to remove the .30" MGs and use only .50" on planes.

autogun

From: autogun

26-Aug

hobbes154 said:

Edit: I notice you have changed "GPMG" to "LMG" ;)

Such designations are relative.....

A lightweight belt-fed MG with a quick-change barrel in .276 would normally be an LMG in WW2, but on a tripod and with long-range sights could be a  GPMG.

Farmplinker

From: Farmplinker

26-Aug

Maybe the author will get the book out again now that Collector Grade is no more?

stancrist

From: stancrist

26-Aug

EmericD said:

I thought that the US ground forces started to use the APM2, after large stocks were made available by the decision of the "air force" to remove the .30" MGs and use only .50" on planes.

Can you cite an authoritative source?  I just did a brief search, but found nothing to support that idea.

The only reason for the switch from Ball to AP that I came across supports what I recalled having read:

As discussed in "A History of Modern U.S. Military Small Arms Ammunition, Vol. ll." It is further stated that "in July 1943 the Ordnance Committee reevaluated the basic ammunition requirements for ground combat and decided that, because of the large amount of metal on a modern battlefield, Armor -Piercing ammunition should take the place of Ball for general combat use."

What type of ammo was generally used during WWII? [Archive] - CMP Forums (thecmp.org)

PRM2

From: PRM2

27-Aug

In your bullet drag research, have you come across any research into the 'fumer' effect for reducing projectile base drag?

Page 306 of the Black Rifle book no.1 briefly refers to this in a section that describes the 1970s FABRL project and includes the following quote about the second phase:

'The fumer phenomenon is an approach to reducing projectile base drag by injecting heat and/or mass behind the base of the bullet. A projectile has three drag components; wave drag, skin drag, and base drag. The base drag is the result of a low pressure, "dead air region" behind the base of the bullet. The injection of heat and/or mass.. increases the pressure and approaches an equilibrium state, thereby reducing the base drug component. This effect is similar, but more pronounced than that achieved with tracer ammunition. ' 

taschoene

From: taschoene

27-Aug

The effect is well known at artillery scale -- base bleed shells use gas generators at the base of the round to reduce base drag and achieve significantly increased range.

I did find a paper about tests of fumer compounds in small-caliber ammo.  They tested with 7.62 but the ultimate application was 20mm, where they thought they could dramatically.improver penetration by increasing retained velocity/energy at long range.

https://apps.dtic.mil/sti/pdfs/ADA026147.pdf

PRM2

From: PRM2

27-Aug

Thank you, that is a very interesting paper. I wonder if the closure of Frankfort arsenal in 1977 halted the research and it was wasn't worth progressing due to cost and complexity.

JPeelen

From: JPeelen

27-Aug

The drag reduction by gas blowing into the bullet wake is well known.

The problem is the increased change of drag from shot to shot. This results in increased dispersion of small arms tracer.

While the accuracy requirement for the 7.62 M80 has been a mean radius of 7.5 inch at 600 yards, it is double that dispersion (15.0 inch) for its M62 tracer and M276 dim tracer companions. For snipers, much more restrictive requirements are necessary.  

The increased dispersion of tracer is a drawback that is not considered in the Frankford Arsenal report AD-A026147 mentioned by taschoene. As far as I know, base bleed artillery projectiles also show quite an increase of dispersion.  

  • Edited 27 August 2022 8:58  by  JPeelen
taschoene

From: taschoene

27-Aug

It's odd because, as you say, base bleed is usually said to increase dispersion.  But there are some Swedes who say it actually improves dispersion.  It may depend on how precisely you add gas -- simple burners are inconsistent but fancier approaches may do better?

https://onlinelibrary.wiley.com/doi/10.1002/prep.19760010402

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