M2 to be retired after 94 years of service.

My understanding is that with modern technology you can make a useful explosive round for much smaller projectiles than was possible in WWII. Last time I looked at this most countries chose 20mm as the break point between mg's and cannons for that reason. Which does bring up the question of whether the defition is now out of date if that is the defiing characteristic.

 

I'm sure the definitions do change. But, really, when you get down to something the size of a 20mm the explosive potential would only be effective on unarmored targets - aircraft, trucks. I know the Bradley fighting vehicles use 25mm shells with depleted uranium that were/are effective against armored vehicles. They don't explode but they will pierce pretty heavy armor.

 

The 25mm DU rounds were sabot. I think I've heard of 20mm HEAT rounds but no idea what their pentration would be.
https://en.wikipedia.org/wiki/High-explosive_anti-tank_warhead
Suggest that the most advanced HEAT rounds can penetrate ~7 times the diamter of the round. I doubt 20mm rounds would be that efficient though. Still might be able to penetrate a light armored vehicle though.

I think the 25mm and possible 20 mm HEAT rounds I was thinking of were smart grenade rounds I know it mentions one for the XM25 in:
https://en.wikipedia.org/wiki/XM25_CDTE
I.e. it's a AP round that penetrates 50mm can't see it being anything other than HEAT or HEP/HESH but could be wrong.

 

Did not the M 2 undergo some minor alterations a few years back, I thought a quick change barrel and some other stuff but fundamentally was a sort of modified M2. My memory is suspect.

If so did the designation change . It and the 1911 are certainly testimony to Mr. Browning's genius..

 

Well it went from the M2 to the M2HB (heavy barrel) at some point. There have also been a number of other minor changes. Looking at:
https://en.wikipedia.org/wiki/M2_Browning
It's now the M2A1 and previously there was an M2E2. That page goes into some detail on varriants.

 

The M2 is a bit borderline as an infantry weapon, only a highly mechanized force like US Army could really afford something like it in WW2, besides the massive gun itself the ammo is also quite heavy, any squad having to drag it around on foot would soon get rid of it in favour of something more manageable.

Like all air cooled weapons it cannot do sustained continuous fire, but as the huge majority of engagement scenarios last a few seconds that's not a real limitation.

DU is more likely to get you good penetration with small calibers than shaped charge rounds, especially if fired at high velocity from a rifled barrel though 50mm for a 12.7 is a lot.

 

I remember reading somewhere that they were working on a sabot round for the M2 but it had a penetration problem. Seems it was penetrating the sides of the barrel occasionally. This wasn't considered acceptable. HEAT is only really worth considering for smaller rounds when you have something like an auto grenade launcher in which case you might get enough penetration in something 20mm or more to make it worthwhile. Note that 50mm was for a shaped charge of ~20mm while the rule of thumb would suggest you could get that much or more out of a12.y I suspect that the rule of thumb doesn't work that well once you get much below 30mm.

 

The M903 SLAP round is a saboted light armor penetrating round (the M962 SLAP-T is the tracer version). It uses a .30 caliber tungsten penetrator and has 2-3 times greater penetration ability (both range and armor thickness) than the M2 Armor piercing ball, M8 API, or Mk 211 Mod 0 API (which has a 13 gram Comp-A4 explosive charge). The 7.62 version of the SLAP round was unsuccessful and did come through the sides of the barrel, the M903 is not authorized for use in .50 sniper rifles. The Marine Corps developed the round during the late-1980's and fielded it during Desert Shield/Storm in 1990. The US Army adopted it sometime in the mid-90's.

 

Thanks. Illustrates how fallible my memory is.

 

Not at all, you did remember that the problem with the development of SLAP in the 7.62 was exactly as you described, the sabot would fragment, the penetrator would skew and catastrophic barrel failure resulted, usually with the barrel being penetrated. The increase in penetration in the 7.62 was also not as dramatic as with the .50cal.

 

My dad said that the 50's legendery penetrating capability proved to really be a great life saving asset in Korea. When the Chicoms were performing their "human wave" frontal assaults, their bodies were piled up in heaps in front of his postition. And they kept coming over the top towards them. So he kept firing, at the ones coming over the top of the heaps and then into the heaps to get the ones a little further back, you know, just in case they were thinking of scaling the heaps to continue their assault. The 50 kept them from being overrun many a time he said. That and a lot of ammo. I imagine a lot of nerve would help too. Anyway, I'm sure he'd have an arguement or two about keeping them on until they develope a rapid fire laser-phaser thingee.

He was really PO'd about the US doing away with the 45 too. He plinked a few Chinamen with his, while some were staggering up to the line and got too close to depress his gun down on them. He also bitched about the black boots that I was issued when I was in the Army, always saying the brown boots that they had were better too. Not really sure how that worked into the conversation about 45s and 50s, but he always found a way to do it. Then I'd get up to get a beer for him and ask him to tell the story about when he got wounded and not awarded the Purple Heart for it. Or when the pogue LT wouldn't let him take his Rooskie made semi-automatic pistol home with him when he rotated out. "Well no sh1t, there we were"....

 

the strategy page has an interesting article on this under the title of "the forever machinegun". Unfortunately copy and paste doesn't seam to be working for me to day especially with urls.