Help support TMP

"BS versus ACC" Topic

21 Posts

All members in good standing are free to post here. Opinions expressed here are solely those of the posters, and have not been cleared with nor are they endorsed by The Miniatures Page.

For more information, see the TMP FAQ.

Back to the SF Discussion Message Board

Back to the Modern Discussion (1946 to 2006) Message Board

Back to the Game Design Message Board

Action Log

13 Sep 2012 3:34 p.m. PST
by Editor in Chief Bill

  • Crossposted to Modern Discussion board
  • Crossposted to SF Discussion board

779 hits since 12 Sep 2012
©1994-2017 Bill Armintrout
Comments or corrections?

Wartopia Inactive Member12 Sep 2012 8:20 a.m. PST

No, ballistic skill, not that OTHER BS.


Some fellow gamers and I were discussing a topic the other day that I thought would be interesting to cover here. It pertains to game design theory broadly but is especially important for small unit gaming for moderns and sci-fi.

Games such as Infinity and 40K require a hit roll when shooting and the baseline factor is the shooter's "ballistic skill". In Infinity and the original Rogue Trader weapon accuracy could modify the base value based on range. Lots of games handle shooting this way.

In other games the inherent accuracy number of the weapon is the baseline value and a shooter's special ability might modify the weapon's baseline number.

So the baseline "to hit" value for shooting can reside in the model or in the weapon. You can have precisely the same probabilities with the two different approaches.

Personally I prefer the baseline to reside with the model and modify that number for stuff like weapon accuracy and/or range. But I've noticed that when running games for brand new gamers they tend to look to the weapon stats for this value since you're already looking there for stuff like weapon range, rate of fire, damage capability, etc. I've tested it both ways and consistently, in the absence of specific direction, people seem naturally inclined to look to the weapon for baseline accuracy and to the model as the modifier (eg "Assault rifle hits on X and when wielded by a militia it's -1 while spec ops get a +1").

So, what's your preference: do you prefer baseline hit probability to reside in the model's BS (ballistic skill) and modify that for weapon accuracy/range?

Or do you prefer baseline hit probability to reside in the weapon's ACC (accuracy) and modify that for model skill level wielding the weapon?

Again, a system with the BS approach can be completely the same statistically as a system with the weapon ACC approach. While I personally prefer the BS approach it just seems more natural for people to look to the weapon for baseline ACC since they're already there looking at range, ROF, etc.

Thomas Whitten12 Sep 2012 9:45 a.m. PST

When it comes to a miniatures game, you have models on the table. The idea of a separation of weapon from its operator (rifle and militia) is an abstract one.

So, I don't think it matters. If you want the baseline to be with the operator have it there. That is a seperation that makes since for the force building part of a game. What matters in game is that all the information (stats) pertaining to what a model does on the table be in one place. So any abstract separation in the rules is combined before play. During the game, the player shouldn't have to look up base and modifiers for operator and weapon. For the game, that data should already all be combined as much as possible. So the -1 for the militia is already combined with the weapon base as part of the BS. The same goes for the +1 for spec ops.

Personal logo Ditto Tango 2 3 Supporting Member of TMP Inactive Member12 Sep 2012 9:57 a.m. PST


Gabriel Landowski Fezian Inactive Member12 Sep 2012 10:00 a.m. PST

To me I assume the weapons systems are of sufficient quality that I don't worry about its accuracy. While it is true you could play a game where inferior weaponry provides a -1 penalty to hit, this penalty is applied to the figure's rated ability with the weapon.

So, yes, to hit is determined (to me) by the ability of the figure to wield the weapon, and not the weapon's accuracy or quality itself.

Wartopia Inactive Member12 Sep 2012 10:06 a.m. PST

I agree in theory with Tom but it depends on the game and how much data want and how flexible you want the system to be.

For example:

- assault rifle accuracy: 3
- bolt action rifle accuracy: 4

- militia -1
- spec ops +1

Here, for the vast majority of average troops, you generally need two data points to remember: the accuracy of the two rifles. The exceptions which are the troop quality brings the data points to four. And remembering that average troops do NOT get modified is easy…you only mod the abberrations…better and worse troops.

If you pre-calculate the accuracy values then you end up with six very different data points which are more difficult to remember relative to one another since there's no mnemonic "reference point"…

Average AR: 3
Average BAR: 4
Militia AR: 2
Militia BAR: 3
Spec Ops AR: 4
Spec Ops BAR: 5

The number of data points using a mod remains linear as you add weapons and skill types. Those explode geometrically if you pre-calculate them since you must multiply the number of weapons in the system times the number of troop types.

Games such as FOW are similar to the first approach but simply use target skill as base value and mod only for one range band with weapon max range limiting weapon reach.

Wartopia Inactive Member12 Sep 2012 10:16 a.m. PST


I agree if we're only talking about slug throwers but what happens when you throw in weapons which increase the chances of scoring a hit through means such as area effect or being guided?

For example, you have two soldiers of different quality each taking turns firing two different weapons. One weapon is a slug thrower sending a single round down range. The other throws an explosive round that sprays an area thus increasing the chances of hitting the target (think some current/near future/sci-fi air bursting rounds.)

Certainly the higher quality soldier has a better chance hitting with the slug thrower. But both have a better chance Relative to their personal baseline of hitting with the air burst weapon since they only need to be roughly on target instead of perfectly on target.

In fact, one could argue that the history of small arms develop is based on the premise that the average soldier isn't all that great a marksman under combat conditions and needs to throw lots of lead down range to increase his chances of hitting something. It's why armies use assault rifles instead of sniper rifles as their basic weapons, even weatern armies.

Thomas Whitten12 Sep 2012 10:19 a.m. PST

Those explode geometrically if you pre-calculate them since you must multiply the number of weapons in the system times the number of troop types.

I see your point there. (My miniatures collection became untenable due to such a geometric progression.) And if I relied on memory, I'd have a problem. No matter the system, I like having data cards to go along with each type of model on the table. Under twenty models per side, I'll have a card per model (with individual name.)

It is on this card that I do all the combining. Thinking about it, maybe not the best way for experienced players. It has, though, helped me a ton in con games.

Wartopia Inactive Member12 Sep 2012 10:24 a.m. PST

Since Gabriel raised such an interesting point let's look at that in more detail using this near future/sci-fi example with two soldiers and two weapons…

Private Average
Private Elite

Semi-Automatic Slug Throwing Rifle
Programmable Air-Bursting Frag Round

Both soldiers clearly have a baseline capability of successfully using both weapons. But Pvt. Average is more likely to hit a target with the air-bursting round compared to the slug. Same goes for Pvt. Elite.

If the Air Bursting round has some sort of proximity detection, so much the better. Pvt. Elite is still more likely to put the round where it can do damage, but Pvt. Average is going to be much happier firing the air bursting round than the one bullet.

So the question becomes where do these skill and weapon capability values reside?

Wartopia Inactive Member12 Sep 2012 10:27 a.m. PST


That wa the approach taken by AT-43 and I liked it very much. The only problem was when I started making cards for all of our troops. Became a real pain in the butt and impossible just to "throw down some troops and terrain" and go at it. I made some really nice custom cards for each jnit but gave up and went back to more flexible data sheets with less stuff to remember.

Thomas Whitten12 Sep 2012 10:33 a.m. PST

Then I think go with ACC (though I prefer BS as well) because it caters better to what you see as the gamers natural tendencies.

Wartopia Inactive Member12 Sep 2012 10:38 a.m. PST

Just thinking some more about what Thomas suggested and there is probably a useful middle ground.

For our home grown rules we have a generic sci-fi army data sheet but we also have custom sheets for specific races (eg for our Necron collections…mine is different from my son's).

Since the sheets can be specific to a faction you can, to some degree, build in weapon and troop capability.

For example, our Space Orks are generally poor shoots, IG are average, and Space Marines above average. If a given weapon were to appear on all three reference sheets you could just tweak the weapon accuracy and avoid a troop quality mod excpet in special cases.

So IG bolters are ACC 3 while Space Marine bolters are ACC 4. And the IG sheet would need only one special rule/mod for our Storm Trooper figures (+1 to hit). They could be given a "Marksman" special rule.

Thomas Whitten12 Sep 2012 10:38 a.m. PST

How many skill values do you have vs weapon capability values? If you have 3 or 4 skill values green, normal, vetern, elite and a ton of different weapon capabilities, which is easier to remember? For me it would be the skill values. So the player looks up the weapon and adds the skill (without looking up).

Wartopia Inactive Member12 Sep 2012 10:40 a.m. PST

I think we cross-posted but hopefully my idea in the post above yours addresses the issue.

Broadly I can see a need for just two "exceptional" BS special rules: guys who are poor shots and those who are better than the army's average.

Wartopia Inactive Member12 Sep 2012 10:42 a.m. PST

I should note too that for our rules troop quality goes way beyond shooting skill. It includes other stuff like Mojo, CC skill, etc.

Thomas Whitten12 Sep 2012 10:47 a.m. PST

Nice, sounds like you have a good handle on it. I think what you have come up with will work well.

Wartopia Inactive Member12 Sep 2012 10:51 a.m. PST

Thanks for the help in noodling it through!

Elenderil13 Sep 2012 4:42 a.m. PST

It makes sense to me to start with the soldier as he is the one using the weapon. The weapon stats will stay the same but the soldiers skills may change as a campaign develops. Also as gamers it is the soldier we identify with rather than the weap[on.

Lion in the Stars13 Sep 2012 4:05 p.m. PST

I certainly identify with the Soldier's skill and the weapons accuracy modifying that (Infinity style).

I think the difference comes from the online gamers where a new weapon gives a new hit%, and it generally doesn't matter what the character's skill is. This is basically a programmer's crutch to use fewer table data-calls.

tnjrp13 Sep 2012 11:36 p.m. PST

Wartopia 12 Sep 2012 8:20 a.m. PST:

So, what's your preference: do you prefer baseline hit probability to reside in the model's BS (ballistic skill) and modify that for weapon accuracy/range?
If the game doesn't feature troopers with different skills (at the mechanic's level of resolution) picking up weapons from less skilled troopers and/or campaign rules where such skill differences may develop, then it's pointless to represent a separate skill value for the trooper and have modifiers to that based on the gun. Having single target number for a trooper to hit with a weapon is much more expedient. Most games I play at all regularly are of the sort where a single target number would suffice but still most of them do go the "BS + modifiers" route so it prolly is what designers like and/or think the players will like.

Wartopia Inactive Member14 Sep 2012 6:02 a.m. PST

Went through our data sheets and it looks like to minimize data points it will be better to stay with BS + weapon mod. However, we don't need an ACC column since only certain weapons get a mod.

For example, the difference in accuracy between a 7.62mm semi-auto rifle and 5.56mm assault rifle is best handled in effective range and shooter skill. Our ARs can shoot 24" beyond which a negative BS mod kicks in for range for other weapons. Out "battle rifles" can shoot 36" and so they can shoot farther than the ARs but at reduced BS and a lower ROF. Thus you get the weapons' relative strengths: the ARs are superior at the shorter, typical tabletop engagement ranges while the battle rifles can shoot farther but produce less firepower.

Meanwhile weapons such as blast weapons, flame throwers, etc. get BS+1 in their notes column and some others such as pistols and SMGs get a BS-1 note. All is right with the world again. :-) This also eliminates the need for "special rules" and terms related to hit probabilities for area effect weapons (see related thread!).

As a video/computer gamer who has played "shooters" since the original Doom I gotta say Lion has it 100% wrong.

Yes, as in real life, different video game weapons have different levels of accuracy. But you take three gamers such as my wife, my son, and me and put us in a Call of Duty team death match and my wife probably won't score a kill, my son will get a solid positive KDR (kill death ratio) and I'll have a huge positive KDR with very few deaths regardless of which weapons we use.

In fact, hardcore gamers often ignore what they consider to be "noob" weapons with which it's too easy to kill and instead use weapons they consider to be a challenge. Online shooters are definitely about skill and not just aiming and shooting skills: far more important are knowing terrain, how to move across the battlefield, and how NOT to get killed if you want to actually win in TDM or objective based games. And since most games include a "kill cam" to hint at the killer's location good players need to know how to shoot-n-scoot well. Even skills such as how to use concealment are important (eg don't skyline yourself, don't poke your weapon out of window, look around rather than over walls, etc.) My son even stopped challenging me to one-on-one Call of Duty matches since I'm able to track him and repeatedly wound him without him knowing where I am as we move across the battlefield.

Zelekendel Inactive Member14 Sep 2012 9:36 a.m. PST

AT-43 had a system where all the unit's weapon systems were listed in the unit entry with their respective accuracy values. The same weapon could in theory have different Accuracy values with different units (though I don't know if they actually did that). Still, the end user only had to look at the ACC value to know how accurate the weapon was and at what ranges. There were no separate "ranges", the accuracy value was compared with the distance to target and the roll required to hit was determined that way. This had the side-effect that sniper rifles hit automatically in close quarters, not necessarily something to be desired…

Sorry - only verified members can post on the forums.