Overheating & ammo - an interesting discovery

[waveform]

Just thought I'd put this out here, as I've never noticed this before...

Sometimes I shoot away my excess ammo with a machine gun, since that seems to increase Heavy Weapons skill. Today I was emptying drums of 7.62x39 ammo with an RPD, when I noticed the weapon overheated sooner than usual. Anyway, after some solid checking and testing, I discovered the ammo type affects how soon the gun overheats! Or rather, some ammo seems to be "dirtier" than other types. Damn! I've never seen anything like this in any game!

The test :
Round #1
RPD (in perfect condition) with 7.62x39 FMJ Ball ammo
At first, waited 5 minutes to make sure gun is fully cooled down
100 round burst
Gun gets 'Overheated' after about 70 rounds fired
After firing 100 rounds - Weapon condition: 3% Dirt: 9%

Round #2
Repaired the RPD with weapon repair kit
Waited 5 minutes
Loaded the RPD with 7.62x39 57N-something ammo (100 rounds)
100 round burst
Gun does NOT overheat during the burst
After firing 100 rounds - Weapon condition: 0% Dirt: 3% !!


I have to say though, it reads in the 7.62x39 FMJ ammo description that it is inferior, but still.. Damn, this game just keeps surprising me. I still need to test if same applies to 5.56mm Ball and M885 ammo...