Recoil for Single-Shot Weapons

[Ulzgoroth]

Originally Posted by roguebfl

Rcl is about shot grouping. weapons deigned to hive tight grouping has a low Rcl weapons with a wide shot grouping (weapon desgined to sprey) have a high Rcl.

This may make sense, but it doesn't appear to be true.

Rcl 1 pretty consistently indicates 'this weapon has exceptional properties that mean felt recoil won't affect shot distribution'. Whether that's because the recoil is negligible (beam weapons, multiple rocket launchers) or because the shots are away before the recoil is felt (shotloads, high-cyclic bursts).

Rcl 2 is characteristic of any guns that don't have such exceptional properties, unless they've got particularly strong recoil-to-weight, in which case they wind up with Rcl 3+.

[kdtipa]

The more I think about this, the more I want there to be some mechanism for carrying over from one round/turn/second to the next. Firing on round 1, and then firing again on round 2 seems like continuous firing to me. Why would the Rcl reset? As it stands, the rule is basically a way to have a penalty for consecutive shots in one round without having to roll the dice for each shot.

If you have something with full automatic fire that has an RoF of 10 and a Rcl of 1, each subsequent shot is less likely to hit than the previous. I know that the rules say it doesn't matter which shot it is that hits. If you make your attack roll with this example and you make it by 2, any three of the 10 shots hit (could have been the 3rd, 4th, and 10th for example).

Now if you fire on full auto one one round, and then again on the next, why do the numbers reset? The spray of bullets hasn't stopped. Why would the probability of hitting on each round be the same? The rules as they are now mean that the shots you fired on round 1 have no bearing on the shots fired on round 2. That makes no sense to me at all.

Based on this thread/discussion, I'm coming to the conclusion that I dislike the Rules As Written for Rcl.

[Ulzgoroth]

Originally Posted by kdtipa

The more I think about this, the more I want there to be some mechanism for carrying over from one round/turn/second to the next. Firing on round 1, and then firing again on round 2 seems like continuous firing to me. Why would the Rcl reset? As it stands, the rule is basically a way to have a penalty for consecutive shots in one round without having to roll the dice for each shot.

Well, there's your problem: that's not what the rapid fire rule represents.

It's true that a rule that did represent that might look the same. (And yes, that is indicative of a problem with the rule.) But trying to make the rule a better fit to a model that is neither what it's meant to fit, nor a good model, is not a fix.

[kdtipa]

Originally Posted by Ulzgoroth

But trying to make the rule a better fit to a model that is neither what it's meant to fit, nor a good model, is not a fix.

I think I disagree with two of your assertions in that sentence. First I disagree that a penalty on consecutive rounds of firing wouldn't be a good model (that's what's you're saying right?). Second, it seems to me that it would be fix.

An off the cuff house rule for Rcl
Rcl works as normal such that each multiple of Rcl your Margin of Success accounts for means another shot hit the target after the first one at MoS 0, and up to the RoF. If the weapon is fired on the following round, subtract Rcl from the skill as a penalty to model continuous fire without recovering. Otherwise, the character firing the weapon can use a ready action to recover and reset the penalty.

[Ulzgoroth]

Originally Posted by kdtipa

I think I disagree with two of your assertions in that sentence. First I disagree that a penalty on consecutive rounds of firing wouldn't be a good model (that's what's you're saying right?).

I am saying that, yes.

And it's a horribly wrong model for many weapons. I don't really have anything to add to what I posted previously:

Originally Posted by Ulzgoroth

It's wrong both for proper machine guns, which are not pushed off target while firing long bursts, and for (at least) light-caliber pistols which take much less than a second to recover from the recoil. I suspect the only things that it might be right for are lightweight, poorly-balanced full-automatic weapons.

A machine gun can steadily fire a stream of bullets at the same aimpoint for multiple seconds. This is a bad way to use a machine gun most of the time, because it overheats it, and because your target is unlikely to need that many bullets. But not because you won't be able to hit anywhere near what you're aiming at after the first second!

And, well, a light semi-automatic pistol also doesn't start flailing around like a dropped fire-hose when you fire it rapidly.

Originally Posted by kdtipa

Second, it seems to me that it would be fix.

That's not really distinct, since my sentence was a conditional form.

[swordtart]

Originally Posted by Ulzgoroth

The short answer without room for me to overreach my knowledge is 'relativity'.

To expand on that a bit, I'd suggest that rest mass is more meaningless than it is zero for something which is moving at c in all reference frames.

In any case, light most definitely does have momentum. You can verify this easily by searching on the subject.

I have now done so and unconditionally withdraw my question. How could I forget solar sails!

That is what you get for playing Car Wars and drinking beer when you should have been studying quantum mech (plus it was all 25 years ago in a university far far away and those equations still give me the willies).

As for the rest I am content to chalk it up to the Rcl stat not being what it purports to be (or not being very good at simulating what it wants to be).

[kdtipa]

Originally Posted by Ulzgoroth

A machine gun can steadily fire a stream of bullets at the same aimpoint for multiple seconds.

Then why make the distinction between rounds? On one round the more accurate way to model it in game would be to skip the Rcl entirely and have the player roll for each shot, since what you're saying is that the previous shots don't affect the aim. I've never fired a full auto firearm before, but with pistols (9mm mostly), I notice that if I fire as fast as I can, I'm much less accurate than if I pause after a "burst" of three (three consecutive trigger pulls), or even better, pause after one shot. I get that this is anecdotal evidence (and therefore not useful scientifically), but it's what I have to go on.

[Edges]

Since no one has linked the uFAQ for this, I guess I will. FWIW.

[Varyon]

Originally Posted by kdtipa

Then why make the distinction between rounds? On one round the more accurate way to model it in game would be to skip the Rcl entirely and have the player roll for each shot, since what you're saying is that the previous shots don't affect the aim.

Even if this is the case, do note that this isn't something that's all that feasible in play. Nobody wants to sit around while the guy with RoF 30 rolls 30 freaking times. You'll also cause a ridiculous inflation in critical rates.

Originally Posted by kdtipa

I've never fired a full auto firearm before, but with pistols (9mm mostly), I notice that if I fire as fast as I can, I'm much less accurate than if I pause after a "burst" of three (three consecutive trigger pulls), or even better, pause after one shot. I get that this is anecdotal evidence (and therefore not useful scientifically), but it's what I have to go on.

Those results actually mesh well with current GURPS rules - pausing after firing a 3-round burst (full RoF for a pistol) allows you to re-establish your Aim between shots. As noted, the current rules actually work alright when you have a situation of humans using modern small arms against humans.

That said, I actually did experiment a bit with the idea of taking a penalty based on Rcl for not pausing between shots in my Initiative Overhaul. That has the disadvantage of being chained to the bulky Initiative system, however. You could probably excise it, although that still means a character might be rolling upwards of 5 times for a single attack.

[Ulzgoroth]

Originally Posted by kdtipa

Then why make the distinction between rounds? On one round the more accurate way to model it in game would be to skip the Rcl entirely and have the player roll for each shot, since what you're saying is that the previous shots don't affect the aim.

Well, bear in mind that you've put me in the position of justifying a mechanic I've already said I think is quite bad...

Main reason: because they don't want that many rolls! I'm given to understand that GURPS 3e did something like that (rolling for small batches rather than single shots I think) and that this was something they wanted to get away from. So, roll for each shot is right out.

There are other reasons. The autofire mechanics are covering a lot of ground, probably too much for any single mechanic to cover without a loose fit. For some weapons, previous shots likely do affect the aim significantly. If a gun has rcl > 2, that's probably why, and some light rcl 2 full-auto weapons may suffer as well. These are probably why the stat is called 'recoil'! For those guns some kind of cumulative penalty on consecutive rounds of rapid fire might be correct.

Even for a gun where recoil is easily controlled from shot to shot, firing more discrete shots in the second means less time to aim (within the Attack maneuver) each one. So something making 3 semi-auto shots less accurate than 1 semi-auto shot is appropriate for any weapon.

For heavier full-auto weapons where recoil doesn't really mess up your aim, you're still not usually going to hit a target with all of your shots in a burst, unless it's a pretty big target. Your shots are spread over a cone which, at the ranges the weapons are meant for, is usually bigger than an individual target. For even better fit, in at least some cases the scatter in the cone is in part from the working of the gun during automatic fire, so if you fire a single shot it really is much more precise. (Vietnam sniping with M2 HMGs...)

Originally Posted by kdtipa

I've never fired a full auto firearm before, but with pistols (9mm mostly), I notice that if I fire as fast as I can, I'm much less accurate than if I pause after a "burst" of three (three consecutive trigger pulls), or even better, pause after one shot. I get that this is anecdotal evidence (and therefore not useful scientifically), but it's what I have to go on.

Note that GURPS models that already without modification. If you pause after a burst, you probably Aim, which has obvious benefits for the next shots. And if you fire three shots in a second, you need a roll 4 (well, 2xrcl) better to hit with 100% of shots than you do if you fire only one shot in a second.

So if what you want is for one shot every other second to be the most accurate way to shoot, you've already got that.