autogun said...

Don't forget that in my revised TFW the .276 replaces the .303 only in infantry squad weapons: rifles, ARs and LMGs. The .303 (in Mk VIII form) remains in use in legacy Vickers and Browning (for AFVs) MGs.

OK, that makes sense. Still not convinced on the weapons development timeline though.

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

stancrist said...

M2 Ball was replaced by M2 AP as the standard combat load about midway through WWII.

Which had even more energy and recoil, yes?

What was the reason? I thought if they wanted to save lead they would have used mild steel.

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.

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.

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.

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

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:

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

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. ' 

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

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.