Torso destroyed ... ammo explosion

[Mechwars]

Hi guys,

we play with the battlemech manual rules set.
In our last game we faced the following problem:

One mech got his side torso destroyed.
In the torso location was ammunition.
Do we have to roll one time to see if a critical Hit "hits" the ammunition?

For example i roll a 9. So 1 critical Hit. Now i roll in the internal section to see if it hits the slot of the ammo. If this does not hit the ammo slot, the critical hit is just discarded and nothing else happens?
And if i roll for example just a 5, then nothing happens and there is no ammo Explosion?

And: the arm (including all arm mounted weapons) is also lost for the rest of the game, because of the destroyed side Torso.
Anything else we have to consider here?

Thanks in advance!

[garhkal]

IIRC the pilot would still suffer the 2 'head hits' from the ammo exploding. 

[Mechman08]

Your example is correct.  When a section with explosive components is destroyed, there’s a Determining Critical Hits roll made to see if any of them go off (with the attendant catastrophic effects).  After that, the section is effectively severed from the mech.  The arm attached to the destroyed torso section also falls off, but no crits would be rolled against the arm’s components.  BMM p.41 has the step by step.

[toomuchcucumber]

As a side note.
In Total Warfare p. 122 it does not have this rule. Does that mean that under TW rules it would not require a roll for explosive components and simply be considered destroyed? Instead the rules would require that you roll a to determine a critical hit once (for hitting internal structure) and if it happens to hit ammunition, you follow the rules to apply damage from explosion?

Is there a reason for this discrepancy or am I missing something?

[Mechman08]

I reread the BMM p.41 and TW p.122 sections dealing with this.  The wording is a little different, but the end result is going to be the same.

Let’s take a look at a COM-2D Commando that takes a Gauss Rifle hit to the Left Torso (15 damage vs. 6 armor, 6 structure).

Following the BMM steps, we have:
1.  DOES THE LOCATION/FACING HAVE ARMOR?
Yes; spend 6 of the 15 incoming damage ticking off the armor pips.  Go to Step 2.
2.  IS THERE DAMAGE REMAINING?
Yes; 6 more damage is applied, ticking off the structure pips.  Go to Step 3.
3.  DOES ANY INTERNAL STRUCTURE REMAIN IN THE LOCATION?
No; go to Step 5.
5.  ARE THERE EXPLOSIVE COMPONENTS IN THE LOCATION?
Yes; roll to determine crits, and see if any tag the ammo bin.  If yes, resolve the explosion (2 Pilot hits plus probably fatal ammo explosion damage).  If no, go to Step 6.
6.  IS THERE DAMAGE REMAINING?
Yes; go to Step 7.
7.  DID THE DAMAGE RESULT FROM AN AMMUNITION (OR OTHER INTERNAL COMPONENT) EXPLOSION?
No; transfer the remaining damage to the CT and return to Step 1.

Also note, now that the LT is destroyed, the torso destruction rules on BMM p. 45 apply.  Further hits in this phase that strike the LT (or LA) will automatically transfer towards the CT.

Following the TW p.122 steps:
1.  Does the location have armor?
Yes; apply 6 of the 15 damage ticking off the pips.
2.  Is there damage remaining?
Yes; go to step 3.
3.  Does the location have an internal structure?
Yes; spend 6 more damage ticking off the pips.  Go to Step 4.
4.  At the beginning of the current phase, did the location contain any components that could sustain a critical hit?
Yes; roll Determining Critical Hits and apply.  Go to Step 5.
5.  Does any internal structure remain in the location?
No; all crits and remaining armor are destroyed without exploding.  Go to step 6.
6.  Is there damage remaining?
Yes; go to Step 7.
7.  Did the damage result from an ammunition (or other internal component) explosion?
No; the remaining 3 damage transfers to the CT and the process repeats from step 1.

I think the confusion is in the wording of TW steps 4 and 5.  You will have checked for and resolved any crits (including possible explosions) before getting to step 5, where everything in the destroyed section is crit out (without detonating).

[NeonKnight]

As a side note.
In Total Warfare p. 122 it does not have this rule. Does that mean that under TW rules it would not require a roll for explosive components and simply be considered destroyed? Instead the rules would require that you roll a to determine a critical hit once (for hitting internal structure) and if it happens to hit ammunition, you follow the rules to apply damage from explosion?

Is there a reason for this discrepancy or am I missing something?

You need to look on Page 124 of TW under DESTROYED LOCATION

Destroyed Location: When a location is destroyed, rather
than just damaged, no check for critical hits in that location is
made unless it contains one or more explosive slots. In that case,
any resulting critical hits that strike explosive slots in that location
are resolved as normal (see Ammunition, p. 125); hits that
do not are always discarded without transferring.

[Xotl]

Yes, TW stashes it two pages later, away from most of the rest of the process, which is why it tends to be missed.

[Charistoph]

It should also be pointed out that if the 'Mech does not have CASE, and that Ammo Bay is Hit by the Crit, it will explode in to the Center Torso's Structure (provided that there is Ammo left and it is not inert like Gauss or Plasma Ammo).

[Paul]

IIRC the pilot would still suffer the 2 'head hits' from the ammo exploding.

Only if a critical hit resulted in an ammo explosion. If the location is destroyed without the ammo going off, there is no pilot damage.

For example i roll a 9. So 1 critical Hit. Now i roll in the internal section to see if it hits the slot of the ammo. If this does not hit the ammo slot, the critical hit is just discarded and nothing else happens?
And if i roll for example just a 5, then nothing happens and there is no ammo Explosion?

And: the arm (including all arm mounted weapons) is also lost for the rest of the game, because of the destroyed side Torso.

All of that is correct.

Anything else we have to consider here?

Just that if that final check does result in an ammo explosion, you do not check fort additional critical hits in the location that was destroyed.
For example, Location (RT) has 2 tons of ammo. Internal structure is destroyed, the critical hit result is an 8 or a 9, and the location is one of the 2 tons of ammo, which explodes. This will cause damage to the next location (unless CASE as someone pointed out) and likely would cause a critical hit check in the new location (CT in this example) if it doesn't outright destroy that new location. But you wouldn't make another check to see if that second ton of ammo in the RT also took critical damage.

[Daryk]

Pilot damage from a side torso being destroyed is an HBS thing...