Sorry, I'm still not seeing how your method is accurate.

I'll use a new example for simplicity.

New Example.

Assuming you've already rolled location as Side Torso & you have 7 slots in this new example.

Upper 6 = 3-XL Slots + 3-DHS Slots

Lower 6 = 1-MedLas + 5-Empty/Roll Again

Using your formula the odds of hitting the 7 slots in the breaks down below.

XL = 50% Top * 50% (3/6 Slots) = 25%

DHS = 50% Top * 50% (3/6 Slots) = 25%

MedLas = 50% Bottom * 100% (1/1 Slots) = 50%

I know its been 25 years since I took any sort of Math or Statistics course but I do know you don't have a 50% chance of hitting a ML when its 1/7 slots in either Side-Torso location.

It looks like your procedure isn't accounting for Roll Again Slots which is making the 50/50 top bottom role irrelevant and all slots equal.

You have 7 slots on what is effectively a D12 Roll using 2 D6's to determine the D12. Each slot has an equal chance of rolling thanks to the roll again.

I did miscalculate.

You need a "6" for the right torso, which is a 13.88% chance on 2d6.

Accounting for the "roll again spots: 2/3 viable slots is a 67% chance.

And, the 50% needed to roll "bottom".

13.88%* 67%* 50%=4.6% chance of hitting those ammo bins.

In your example:

13.88% chance of hitting the RT * 50% chance of "bottom" * 100% (you can ONLY hit the medium laser if everything else is "roll again")= 6.9%. And, with floating crit rules, that's pretty high because the medium laser is the only viable slot in that area.

Since we're talking about floating crits, you need to include the probability of hitting different locations as that drastically lowers the probability. With CT crit rules, you don't have that extra roll which dramatically increases the chance of doing tearing up an engine or a gyro. Even with all of the tinkering with multiplication, you're typically looking at a 10x greater chance of hitting a gyro under CT rules than hitting something critical with floating crits. Bear in mind that taking out a big weapon with a lot of slots is much more probable with floating crit rules. Let's look at taking out an LRM in that Timber Wolf Prime with floating crit rules:

13.88% chance of LT* 50% of hitting "top"* 50% chance of hitting the LRM= 3.5%

13.88% chance of LT* 50% chance of bottom*50% chance of hitting LRM= 3.5%

13.88% chance of RT* 50% chance of "top" *50% chance of hitting LRM= 3.5%

13.88% chance of RT *50% chance of "bottom" * 33% chance of hitting LRM= 2.3%

3.5%+3.5%+3.5%+2.3%= 12.8%