Spotlight: Never Tell Me The Odds

This week, we’ve got another article from Bolt Action maths whiz Rob Cook – he’s been taking a look at playing the odds with anti-tank weapons!

The last game I played featured little in the way of substantial anti-tank assets. No big cats for my Germans, no super heavy 17 pounder for my British opponent. Yet the three armoured vehicles on the table still ended up in flames. How was this so? Are the big AT guns overrated? Will a light AT gun or a one-shot Panzerfaust suffice? Time once again to look at some statistics!

On Paper

Unlike my previous article on the statistics of shooting in Bolt Action, AT weapons have a few more variables in play. Penetration value and hitting the side or rear armour, can all affect the odds of brewing up the enemy. Before we look at those complications, let’s establish a baseline set of odds for AT guns under idealised conditions.

In your sights is an enemy AFV – front on, in the open, not at long range, and your firing unit is not burdened with any pins. What are the odds of that single shot letting you roll on the damage chart?

A 3+ is needed to hit, so that’s odds of 4/6 – or approximately 66%. Penetration requires a roll that equals or exceeds the target’s armour rating. We think of this as a D6 roll plus the pen value, versus the target armour, but we can equally think of it as a D6 roll, versus the target armour minus the pen value. So for a light AT gun (pen value +4), against a vehicle with 7+ armour, a roll of 3+ is needed to penetrate it – odds of 4/6. Taken together, the odds of getting to roll on the damage chart are approximately 44%.

That’s not great. Especially as the damage chart only gives us a 1/2 chance of actually destroying the vehicle first time around (or not at all if we only equalled the armour rating on our penetration roll). What do the rest of the odds look like?

Weapon 7+ 8+ 9+ 10+ 11+ 12
Light AT (+4 Pen) 44% 33% 22% 11%
Medium AT (+5 Pen) 55% 44% 33% 22% 11%
Heavy AT 55% 55% 44% 33% 22% 11%
Super Heavy AT 55% 55% 55% 44% 33% 22%

In Bolt Action, AT guns behave the same whether they are static artillery pieces or mounted in an AFV, so the odds above apply to both. Another thing to bear in mind is that a roll of a 1 when trying to penetrate a vehicle is always a fail – so there’s a point at which those large pen values stop increasing the odds.

At first glance, these odds look pretty dismal but don’t forget they are for a single shot. If your light AT gun had 6 shots during the course of a game under these same conditions, at a 7+ armour target, the odds of at least one of them giving you a chance to roll on the damage table goes up to approximately 91%.

Lesson learnt – sustained fire at the same target is much better than a one-off pot shot.

Increasing the Odds: Penetration

Taking on an armoured target from the front is seldom wise. Odds aside, if you are shooting at the front of a vehicle, it means it likely has its weapons pointed straight at you in return! Flanking is the order of the day when stalking an armoured target. But how much difference does it make?

Hitting the side of an armoured vehicle typically gives a +1 bonus to the penetration roll; rear armour a +2. Therefore a light AT gun hitting a 9+ vehicle from the side is the same as hitting an 8+ vehicle from the front. Put another way, a light AT gun hitting from the side has the same odds profile as a medium AT gun hitting from the front.

Despite this, there is still an upper limit of 55% odds. The penetration roll will always have to be, at best, a 2+ roll, no matter what pen bonuses apply. To get even better odds, we need to increase the chance of hitting in the first place.

Lesson learnt – attacking from the flanks makes even light AT guns a threat to the big cats.

Increasing the Odds: Range

Weapons in Bolt Action have three ranges – long, normal, and point blank. So far we have assumed our AT gun is firing at normal range (no further than half its maximum range). To do better than that, we need to get to point-blank range – 6″ or less. This is scarily close as far as vehicular combat goes, so is it worth it?

Weapon 7+ 8+ 9+ 10+ 11+ 12
Light AT (+4 Pen) 55% 42% 28% 14%
Medium AT (+5 Pen) 69% 55% 42% 28% 14%
Heavy AT 69% 69% 55% 42% 28% 14%
Super Heavy AT 69% 69% 69% 55% 42% 28%

As before, we can also see the effect of a flank shot by dropping the target armour value by the appropriate modifier when looking up the odds.

If we are going to get this close to a vehicle though, why bother with AT guns at all?

Man-portable AT weapons are a good deal cheaper than a vehicle with an AT gun, and much more mobile than an artillery piece. The decrease in range is a moot point if we are getting close anyway, and shaped charge weapons don’t suffer the -1 penetration modifier for long range (making them viable even at their maximum distance). Add to this the penalty your opponent will suffer for shooting at a small team, and a Bazooka begins to look like a very tempting AT option indeed!

Lesson learnt – if you are going to get in close anyway, use man-portable AT.

Final Analysis

Knowing the on paper statistics of your AT assets can aid in decision making, but in the heat of battle things don’t always turn out that way. On more than one occasion I’ve been on the receiving end of a British Piat team dismounting from a Bren carrier, aiming at a medium tank, and lighting it up first go. Not to mention the time my Pak40 fired an AT round at a lone forward observer holding an objective, hit him, then failed the damage roll despite the enormous pen value. Presumably the shell bounced off his binoculars!

The ridiculous and the sublime are never far away in Bolt Action.