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Hello,

I know Free League wanted to keep things as simple as they could for the game and not dig into the minutia of every single piece of equipment. Still, I wanted to get some thoughts from other GMs on how to cover the blast panels and a few other safety features that exist* on most modern MBTs?

As a quick summation of what I'm talking about: modern tanks like the Leopard 2, Challenger, LeClerc, and Abrams are constructed with Magazine Blow Out panels, which redirect the force of an ammunition magazine detonation in a safe direction that protects the crew and allows the MBT to remain active—making the ammunition coking off in the moment more of a danger for those outside the vehicle when it occurs. Although unless I'm missing it, there is no RAW mechanic to represent this, and all vehicles who suffer an ammunition hit that causes their magazines to explode are immediately destroyed in such a manner as to render them beyond repair.

I was thinking for my games for vehicles so equipped; I might instead play the rules as designed, playing out the explosion on the area around the tank, but rather than having the tank Destroyed, I think I might reduce the vehicle's reliability by D3.

I'm looking forward to seeing peoples thoughts on this,
-Collinsas

*I was also thinking about what to do with onboard fire impression systems, but that's another question for now.

Thing is, those panels aren’t really a “get out of jail free” card in that way. And even when they work as intended, an ammo compartment hit is still an extremely violent event.

If the hit that makes the magazine cook off also somehow compromises the bulkhead between the bustle and the fighting compartment, it may still injure or kill the crew in the turret, if not the driver as well.

Another issue is that the ammo compartment door is a bit of a hassle. Some crews (or loaders) elect to leave it open to save time in loading. A hit can also occur during those precise few seconds when the loader has the door open to collect a round. Also, with the conditions later in the war, the mechanism may even have become jammed, and the door can’t be closed.
And if the door is open when the ammo goes, then the panels do no good whatsoever; the crew is just as dead anyway.

After the event, the tank should be salvageable. It may even be 100% operational, apart from having no magazine, and able to withdraw on its own tracks.

I’d consider introducing a die roll that determines a scale of possible outcomes, from the RAW at one end, to magazine destroyed and needs to be repaired but no other effects whatsoever at the other.

The shock of the explosion of the magazine would knock out many of the tank's systems. One of the reasons the Russians lost so many tanks in Grozny was that the ERA when detonated by satchel charges being tossed onto the tanks jammed the turret and autoloaders and left the tanks crippled and blind.

As Vader pointed out many tanks will be lost due to the doors being open at the point of penetration. The Turks lost Leopard 2s and the Saudis early Abrams due to ammo cookoffs with the doors being left open.

Thought I’d add: the event of the ammunition cooking off can look a few different ways. It can occur as one big explosion, if the hit can somehow ignite a large number of cases simultaneously, but it is much more likely to be a slower conflagration, with huge plumes of fire shooting out from the blown-off panels over a period of several minutes.

With no sealed enclosure to build pressure in, the propellant is apt to burn rather than detonate. Compare how gunpowder acts when you burn it in the open vs. when it’s sealed in something that can hold a bit of pressure.

None of these tanks use metal cartridge cases; they’re all fully or partially combustible, so there won’t be any pressure build-up in the ammunition itself, either.

Note that the ammunition burning will severely heat up the bulkhead and door. And you will not want to try to exit the tank while the fire is going.

Sorry for taking so long to reply; this has been excellent information. It makes sense that you can't bail out if there is a large fire burning on top of your turret, so what do you think would be a fair replacement reaction in such a situation? Beyond that, I'm trying to figure out what would make for a good luck roll to see if your bulkhead doors are closed during the impact?

Thing is, those panels aren’t really a “get out of jail free” card in that way. And even when they work as intended, an ammo compartment hit is still an extremely violent event. If the hit that makes the magazine cook off also somehow compromises the bulkhead between the bustle and the fighting compartment, it may still injure or kill the crew in the turret, if not the driver as well.
(snip)
After the event, the tank should be salvageable. It may even be 100% operational, apart from having no magazine, and able to withdraw on its own tracks.
I’d consider introducing a die roll that determines a scale of possible outcomes, from the RAW at one end, to magazine destroyed and needs to be repaired but no other effects whatsoever at the other.

Very true, the ammunition compartment cook off event in effect it suppresses the crew while the ammunition cooks off.
https://www.youtube.com/watch?v=CP8JiqItigE of a Iraqi M1A1 ammo cook-off event
M1 testing on YouTube https://www.youtube.com/watch?v=yG0zpGCLaVQ&t=375s

When you wrote;

Another issue is that the ammo compartment door is a bit of a hassle. Some crews (or loaders) elect to leave it open to save time in loading. A hit can also occur during those precise few seconds when the loader has the door open to collect a round. Also, with the conditions later in the war, the mechanism may even have become jammed, and the door can’t be closed. And if the door is open when the ammo goes, then the panels do no good whatsoever; the crew is just as dead anyway.

The event of an antitank munition striking the tank at the exact moment the ammo door is open is incredibly small. Really small.

On the mechanism still working after four years of war, well that is another matter. Lets take the M1 ammo door. The Operation of the door is electrically actuated and hydraulically operated by basically a piston. To access the ammunition in the semi-ready rack you must turn off the electrical actuators by turning off the circuit breaker, rotate the manual lock on the Ready rack (the main gun storage of tank ammunition the loader gets the ammo from. Then unlock the manual door and open it. It is very heavy and can be a bear to move if you are on an incline. Once you have the semi-ready door open you can pull rounds out and place them in your lap and then close the semi-ready, lock it and open the ready rack and take those rounds and put them away. I had to do this in Desert Storm (showing my age).
In T2K world where parts are not readily available before 2000 (game start) and the hydraulic actuator or electrical circuit is broken, I would think the crew would have a handle welded on the ready rack ammo door to open it and use the manual lock to keep it closed. If the crew gets lazy or the tank is on an incline and it is hard to close the door, then you are correct, the door is open and the ammo cook-off kills the crew. Sorry folks, even the driver.

So remember that tank commander in 'Fury' when his tank was hit and started burning and he came out and shot himself in the head. Yep, that is likely what will happen if you somehow survived. Even with Nomex fire resistant coveralls.
Anyway, I hope this helps in a small way.
Regards
Muns