Explosive bullets and why they don't matter

Players have long demanded explosive bullets to be implemented, greatly buffing the firepower of Italian and Japanese planes using 12.7mm HMGs for their fighters, which were generally severly out-gunned by US planes using more powerfull 12.7mm rounds.

People swore by the MG 131 capabilities due to also employing explosive bullets, obviously more destructive than mere armor piercing and incendiary bullets.

There also was a voice for doing the same with 7.7mm rifle bullets for light machine guns, with Japan being the only nation to employ a rifle caliber soley explosive bullet, carrying around 0.5g PETN.

Sweden started the whole trend having a 13.2mm explosive bullet, which carries a considerable large explosive amount, resulting in killing power more akin to a 20mm cannon in-game.

Then there’s the US, foolishly only ever employing Incendiary bullets.
What’s up with that?
Did they just miss the opportunity, didn’t they consider it to be worth while or was there simply never be a good reason for it?

The answer: They are not worthwhile.

The full answer: Incendiary filler was simply more effective.

The reason for that can be found in experiments done by the UK during and after the war:

The conclusion from this and the previous experiements were that incendiary filler (flash powder) has practically the same or even better blast performance then using just explosive material.

Due to the high temperature flash and heat relaese from the detonation or deflagration, flash powder achives both great incendiary capabilities as well as pressure inducing damage.

Does that mean that explosive is completely redundant? No.

This is because flash powder and explosives work in different ways.

While flash powder releases a lot more energy in the form of heat and the resulting pressure built up, explosives create a shockwave that is more desturctive.
What this generally means is that explosive are required for effective fragmentation of shells and that they can destroy components with direct hits that can withstand the pressure built-up from incendiary rounds.

The blast effect is particular effective against structurely weak planes like Bi-Planes and planes made from wood were particular vulnerable to the blast effect of explosive or incendiary ammunition.

12.7mm MDZ (~2.85g explosive-incendiary filler) vs. Yak-9 wing

Here it becomes clear why explosive bullets are not worth it:
LMG and HMG bullets are simply too light to have an effective fragmentation effect.

Therefore you get the most bang for your buck by loading the bullet with just flash powder, increasing the destructive performance with enhanced blast effect, while also delivering and incendiary effect that can take out even large planes by setting them on fire.

Both Germany, Italy and Japan learned about the advantages of incendiary ammunition for small and large caliber shells during the war and replaced their previous explosive rounds with more effective incendiary ammunition.

In the end, neither Italian nor Japanese 12.7mm HMGs are able to match the destructive power of US .50cal API or Incendiary rounds.

High capacity bullets like the US M23 Incendiary (5.83g flash powder) and the Japanese Ma-102 HEI (~1.75g PETN + ~1.46g flash powder) were quite effective for their caliber but had issues with bullets detonating prematurely from heated up barrels.

Still, while the M23 Incendiary is too light and thin to posess and fragmentation potential, the blast effect blows all other HMG bullets out of the window.

This shows how inaccurate the current depiction of explosive ammunition is in the game.

If US .50cals had their M23 bullets hit harder than Swedish 13.2mm HE-T, they would simply outperform any 20mm cannon and the BRs of US planes would sky rocket.


The only reason we asked them to model the 12.7mm explosive rounds was because some game mechanics were lacking another way we achieved this was by increasing the rate of fire of the Japanese 12.7mm and Ho-5 20mm cannon and this was the best way at the time to increase their effectiveness we knew about the other rounds and their effective properties but they were’nt modeled properly and without a possible change being visible in the forceable future due to modern tanks and aircraft taking the forefront we took whatever change we could get with the current meta and game mechanics