Why some HMG break wings & others don't

[Pursuivant]

As part of my damage model bug stomping extravaganza, I've started to look at how various heavy machine guns work in the game.

My first test really made it very clear why the M2 .50 caliber MG seems "underpowered" in the game. The answer: lack of HE bullets in the belting.

By contrast, both the UBT 12.7 & MG131 13 mm MG include some variety of explosive bullet in the mix.

Regardless of weight of fire that hits a particular part, the game's damage modeling seems to need an explosive effect to trigger breaking parts for some planes. The MG 131 and UBT have that explosive effect, the M2 doesn't.

This isn't necessarily unrealistic. The USAAF made a clear decision with its choice of the M2 .50 caliber as its weapon of choice, and standardized beltings of AP, API, Incendiary and Tracer bullets. They were out to hunt fighters, not bombers, and their pilots and gunners were trained to go for engines, fuel tanks and cockpits - not airframes.

Looking at gun camera films by USAAF fighters, I don't see many instances where an enemy plane's wing was blown off as a result of gunfire alone (vs. secondary explosion). Reports of Japanese planes falling apart under .50 caliber fire might just be effects of fuel tank explosions or damaged wings failing under high G turns.

But, were the game to allow customized ammo beltings, with the option of including HE rounds for the M2, then I think that there would be no further complaints about that weapon's combat effectiveness.

Edit: There's also an argument to be made that the UBT and other 12.7mm or 13 mm machine guns (but not MG131) shouldn't have any special ability to break parts that the M2 can't. The USAAF did tests using HE bullets for the M2 and came to the conclusion that API shells carried a greater weight of fire. That is, they were the more combat effective round.

Typical .50 caliber, 12.7mm or 13 mm HE bullets of the era carried a very small explosive charge, but with a disproportionate reduction in bullet mass and effective penetration, so there is very good logic to the USAAF's decision.

The exception to the rule was the German 13 mm Minengeschoss bullet, which carried a much larger mass of explosive in a very thin-walled bullet case. These had a much more powerful explosive effect, but at the expense of much reduced penetration.

While the Allies were aware of minengeschoss ammo, for some reason they never reproduced it, since seems odd since it's an excellent choice for hunting fighters.