Classichammer

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?

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.

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.

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.