Alternative Ultra AC rules

[Karasu]

This is just a very basic thought that crossed my mind while thinking about ways to streamline things (by taking out the cluster table).

If fired on ultra mode, when a UAC hits, first roll for hit location of the first part of the salvo as usual.  Then roll for hit location again.  If the second location is not adjacent to (or the same as) the first location using the Damage Transfer Diagram, then it misses, otherwise it hits.

For reference, the links are

• Arm-> Side Torso
• Leg-> Side Torso
• Side Torso -> Centre Torso
• Head -> Centre Torso

Using the 2 column on the cluster hit for twin-shot Ultra fire produces a 41.7% chance of 2 hits.
Using this method produces a 39.8% chance on F/R table and 41.7% on Side table.

Any thoughts?

[Daryk]

Wouldn't it make more sense to just use the regular damage transfer chart (with the addition of the head)?

[Karasu]

Yes, that's what I was talking about.

[Daryk]

Ok... the restating of the links just threw me.

[Sabelkatten]

Do I understand the idea correctly: If I hit the RT the second shot must hit the RA, RL, RT or CT?

Doesn't sound like a terrible idea. Would be interesting to see if it could be used for other cluster weapons as well.

[Karasu]

Yes, that's right Sabelkatten.

I started trying to work out whether it would work with RACs, but things get quite complicated even at 3 shots, and 6 is 262k options!

[Alsadius]

Fire X shots, roll the location dice X times, they're a hit if they're adjacent to the original location. E.g., RAC firing six shots:
1) LT (first always hits)
2) RA (miss)
3) CT (hit, adjacent to LT)
4) RT (miss)
5) LL (hit, adjacent to LT)
6) RA (miss)

Or, if the math of that is too weak, they're a hit if they're adjacent to any location that's already been successfully hit. E.g., with the same location rolls as above:
1) LT (first always hits)
2) RA (miss)
3) CT (hit, adjacent to LT)
4) RT (hit, adjacent to CT)
5) LL (hit, adjacent to LT)
6) RA (hit, adjacent to RT)

It's not too complex in play, though I haven't run the numbers on expected values of either.

[Karasu]

I spent a bit of time analysing the 3-shot odds for the second option (adjacent to an existing hit):

The Cluster table gives an average of 2 hits, the new method gives 1.9 hits.  However the actual frequency is quite different.

Cluster
1  16.67%
2  66.7%
3  16.67%

Transferral
1  40.0%
2  34.9%
3  25.1%


I don't know enough statistics to accurately calculate this in general terms, so I'm doing large arrays and formulae on Excel to get the numbers, but these increase geometrically not arithmetically.

[RifleMech]

This might seem a bit silly but why not have both shots hit the same location and go in as normal? I ask because all the AC rounds normally hit the same location unless you intentionally walk your fire between two targets. Why should the hit separate locations just because you fire twice as fast?

[Alsadius]

This might seem a bit silly but why not have both shots hit the same location and go in as normal? I ask because all the AC rounds normally hit the same location unless you intentionally walk your fire between two targets. Why should the hit separate locations just because you fire twice as fast?

Because then the UAC/20 would be grossly overpowered.

[Daryk]

Heck, it would turn the UAC/10 into a long range AC/20 half the time too.

[RifleMech]

Because then the UAC/20 would be grossly overpowered.

Heck, it would turn the UAC/10 into a long range AC/20 half the time too.

Isn't that the point though? To make autocannons more deadly at the risk of jamming the weapon.

[Alsadius]

Isn't that the point though? To make autocannons more deadly at the risk of jamming the weapon.

More deadly, but not that much more deadly. 40 damage to a single location is just too strong in BT.

Phrased differently: the point of pulse lasers is to make it easier to hit with your lasers, but giving them -5 to hit would still be OP.

[Karasu]

I was trying to find some way to explain that, but having difficulty.  The Pulse Laser comparison is quite a good one.

[RifleMech]

why not give ACs a penalty to hit when rapid firing to reflect recoil? The bigger the AC the more the penalty?

[Karasu]

At that point we're not actually simplifying things, then.

It's an interesting idea, but I feel that it's not accomplishing the goal I set out to achieve.

[Kidd]

Simple: Roll as if making attacks with 2 weapons. What Ultra should have been all along IMO.

It should buff Ultra DPS quite a bit in practice, which is something for those who feel the poor guy's been left behind with all these upgrades and stuff.

[Sabelkatten]

40% damage increase is probably a bit much even for the poor UACs...

[Kidd]

40% damage increase is probably a bit much even for the poor UACs...

Yeah I guess a little...

Okay, then let the second shot hit on a 5+ or 6+. Maybe let it be 8+/7+/6+ or 7+/6+/5+ based on range bands (though I don't much like this type of rule) with the explanation that at close range the targets are harder to track.

[Sabelkatten]

But the OP is about removing the cluster roll completely to simplify play.

If you want UACs to be more attractive how about a -1 TN when fired at high RoF? Keep the jamming rule and the numbers look pretty balanced.

[Kidd]

But the OP is about removing the cluster roll completely to simplify play.

If you want UACs to be more attractive how about a -1 TN when fired at high RoF? Keep the jamming rule and the numbers look pretty balanced.

No, you need the extra damage to offset the heat

Ok how's this. On the usual To-hit roll, the second shot hits any time a 4, 5 or 6 is showing on any die - if my math is right, that's a 72% probability

If just 5 or 6 on any die, that's a 56% probability

[Ruger]

Yeah I guess a little...

Okay, then let the second shot hit on a 5+ or 6+. Maybe let it be 8+/7+/6+ or 7+/6+/5+ based on range bands (though I don't much like this type of rule) with the explanation that at close range the targets are harder to track.

I actually played this way when I first started playing the game, as the group I played with used what they termed "following fire" rules...they actually made units like the Dragon very deadly...and the penalties we used were not as high as you suggest here, but they helped make the AC's competitive or even desirable vs other weapons...so much so that our unit's XO, who was a naturall gunner (Mechwarrior 2nd Edition RPG thing) eventually used a Daikyu modified with 2 UAC-2's (instead of the 5's) over his original Marauder...

If requested, I can try to type up the penalties we used after I get off work this evening.

Ruger

[Alsadius]

40% damage increase is probably a bit much even for the poor UACs...

Depends on the jam rule. "Roll to-hit six times, jam on any single roll of 2-4" basically makes the weapon a one-shot, statistically. Even if it's jam on any roll of 2, that's still pretty rough. I think you can play with that to get something moderately balanced, though it may be frustrating for all involved.

How about "Each shot has a THN that's +1 worse than the previous"? You could maybe even eliminate the jam rule there.

On a base THN of 6, for example, you'd hit with the following number of shots on average:
1: 0.72 shots.
2: 1.02 shots canon rule, 1.31 shots proposed rule.
3: 1.44 shots canon rule, 1.72 shots proposed rule.
4: 1.91 shots canon rule, 2.00 shots proposed rule.
5: 2.28 shots canon rule, 2.17 shots proposed rule.
6: 2.88 shots canon rule, 2.25 shots proposed rule.

This helps smaller bursts a lot, particularly UACs, but big RAC bursts get worse unless the THNs get very low(a 6-shot burst is better than the canon rule on THNs of 2-4, and worse if it's higher).

[Sabelkatten]

No, you need the extra damage to offset the heat

Ok how's this. On the usual To-hit roll, the second shot hits any time a 4, 5 or 6 is showing on any die - if my math is right, that's a 72% probability

If just 5 or 6 on any die, that's a 56% probability

You do realize that better to hit = more damage?

But your idea doesn't really work. It's TN dependent, if you're hitting on 7 and need to roll 5-6 on one die to hit with both rounds it's an 86% chance both rounds will hit if you hit. At TN2 it's 56%, at TN9 it's 100%.

[Kidd]

You do realize that better to hit = more damage?

But your idea doesn't really work. It's TN dependent, if you're hitting on 7 and need to roll 5-6 on one die to hit with both rounds it's an 86% chance both rounds will hit if you hit. At TN2 it's 56%, at TN9 it's 100%.

Yeah I do, but I don't want an accuracy mechanic, I want raw damage at the same accuracy

No, it's not TN dependent. The first shot is as normal. The second shot depends solely on the dice roll. So as with the current Ultra rules, if the first misses then so does the second. Once the first hits, the probability of hitting with the 2nd is as I posted - either 72% if 456 or 56% if 56. The probability is fixed and independent of the TN.

[Sabelkatten]

Yeah I do, but I don't want an accuracy mechanic, I want raw damage at the same accuracy

No, it's not TN dependent. The first shot is as normal. The second shot depends solely on the dice roll. So as with the current Ultra rules, if the first misses then so does the second. Once the first hits, the probability of hitting with the 2nd is as I posted - either 72% if 456 or 56% if 56. The probability is fixed and independent of the TN.

Then which die roll is you referring to? Is it just an alternate cluster roll?

[Kidd]

Then which die roll is you referring to? Is it just an alternate cluster roll?

Sorry, let me demo:

Blitzkrieg fires UAC20. THN is 5. Rolls 2d6.

Result is 4 and 3, total 7. Because 7>5, the first shot hits. Because there is a 4 in the result, the second shot hits. Roll for 2 locations.

Blitzkrieg fires again. THN is 4. Rolls 2d6.

Result is 2 and 3, total 5. Because 5>4, first shot hits. Because there's no 4, 5 or 6 in the dice, the second shot misses. Roll for 1 location.

If the first shot misses, the second shot misses regardless of dice result.

If the rule is "success on 4 5 or 6", the hit probability of the second shot is 72%. If success is 5 or 6, the hit probability is 56%.

[Sabelkatten]

Nope, you've got the math wrong. Or rather, you're not thinking of how many shots that hit if you hit at all.

On a TN of 5 and the second shot hitting on a die of 4+ the chance of hitting with both shots if you hit is 90%. If the TN is 7+ you will always hit with both rounds (100%) if you hit at all (every possible result totaling 7+ contain at least one 4, 5 or 6).

[Kidd]

Nope, you've got the math wrong. Or rather, you're not thinking of how many shots that hit if you hit at all.

On a TN of 5 and the second shot hitting on a die of 4+ the chance of hitting with both shots if you hit is 90%. If the TN is 7+ you will always hit with both rounds (100%) if you hit at all (every possible result totaling 7+ contain at least one 4, 5 or 6).

Ah I see what you're getting at. Yeah I hadn't thought of that. Did my combinatorial math in isolation from the 1st shot, which I shouldn't have.

That'd be pretty OP, heh?  ;D

[Mattlov]

My house rule for Ultras is really simple:  Roll to hit for the first shot as normal.  To represent recoil, the second shot needs the original TN +1.  Roll separate hit locations as normal.  You can only jam on the first shot.

Never understood while firing at the prone, shutdown, adjacent 'Mech the first shot auto-hits (unless it jams!), but that second shot will still need an 8+!

I can see your rule making sense in a semi-realistic way of walking the fire around, but this is Battletech.  Reality is not welcome here.  :)