I talked about that exact issue when I was trying to test .50s on the He-111 in my bug report. I had to use the Bf-110 as a surrogate as it offered direct unrestricted access to the fuel tanks.
Yeah. I wanted to use the Bf 110 in the first place but then ended up with the He 111.
I now tested the Bf 110 and it took around 10 hits to set the fuel on fire. Firing with just one MG at times.
So as expected, the fire chance of guns seems to have been nerfed quite heavily, since there were times where 1-3 .50cal would cause a fire.
You can have it SOMETIMES light up fuel tanks easily. Like on the Bf-109 F-4. But the amount of one shot fires I got pales in comparison to the amount of times like in the video provided where you’re hitting multiple times and you’re not doing much.
Yeah F-4s light up pretty fast using 12.7mm Berezin API-T. Often just one hit is enough from behind.
But maybe it’s due to the round kiling the pilot which lights the AI plane on fire automatically or something.
With Berezin API-T, Bf 110s also seem to take anything from 1-10 to light them on fire. Even though it felt more consistent than with Breda-Safat API-T. So I was thinking the fire chance might be related to the damage inflicted.
Universal belt, F4U-1A (AP-I/AP-I/AP-I/T/I). Made 3 passes: Pass 1 I barely nicked his tail. Pass 2 I didn’t hit any fuel tanks. Pass 3 I hit his engine. Uploaded above is the engine shot causing immediate fire.
- AP-I: M8 Armor-piercing incendiary bullet
- T: M1 Tracer bullet
- I: M1 Incendiary bullet
(notice that although his wing is yellow, i did NOT hit the fuel tank:

)