High Ef Bolt Thrower Math (6th Edition)

[mattyfenby]

Is it EVER mathematically the right call to fire a single bolt rather than the 6?

I tried gaming out shooting at a big terrifying monster like a Giant or a Dragon at long range.

Single Bolt: BS4, need 3s to hit, at long range w large target still 3s to hit. With 100 firing attempts, we would shoot 100 bolts and expect 66 to hit. At S6 vs a T6 target, 4’s cause damage, so we expect 33 of those. They cause 1-3 wounds apiece, with an expected average of 2, meaning we expect 66-67 wounds.

Repeater: Still 3s to hit. 100 attempts = 600 shots. 400 hits. S4 vs T6, 6s wound. 1/6 x 400 = 66-67. Not only does the Repeater generate the same amount of expected wounds, it also provides a safer spread with less of a chance of whiffing entirely with one bad to-wound roll.

Against a T7 target, something unexpected happens. S4 can still manage to generate wounds on 6s, while the S6 attacks slide to only generating wounds on 5s, meaning that counter-intuitively against the tougher target you STILL want those repeater S4 shots.

The only things I can think of is the fact that single bolt denies Armour Save, and the fact that S4 can’t wound a T8 or higher opponent.

Unless you are facing an enemy that is T8 or greater (what would those even be?), is there EVER a good reason to opt for single bolt? Against an enemy with a good Armour Save, does the single bolt become the stronger choice? Have I forgotten something, made an error in my math, or otherwise left something out of this?

[Just Tony]

No, I think you hit it pretty much on the head. I can't remember the last time I fired a single bolt with my repeater Bolt throwers.

[Jonathan E]

Steam Tanks. That's about all I can think of in terms of high-Toughness, multiple-Wound targets with solid armour saves where it'd be worth chucking the single shot out. Maybe some niche case like a 0+ save character.

Volume of fire is generally preferable, given the hit-wound-save whittling down process inherent in Warhammer, and especially when there's the Armour Piercing factor in play to give the multiple shots that little extra fillip.

[Alarantalara]

People have done the math for this before, e.g. https://docs.google.com/spreadsheets/d/ ... sp=sharing
(Ignore the crossbow option—it's for the improved 7th edition version of the dark elves)

Anyway, heavy cavalry flank shots and equivalent are worth it. i.e. 2+ or better save and at least 3-4 "ranks". If the save is 3+ or worse, or you don't have 3 ranks at toughness 4 or 4 ranks at toughness 3, the volley is better. (And yes T8, if you can find it.)

Addendum: While normal heavy cavalry are "worth it", the margin is small (about 1 extra kill/5 rounds of firing). Unless you have a lot of bolt throwers, the reduced deviation from the volley is probably preferable. Always go for the single shot against the flank of chosen chaos knights though.