[Shotguns] Is this a house rule?

[Anthony]

Originally Posted by Ulzgoroth

The rapid fire rules as written aren't particularly realistic or respectful of physics. While they do suggest a physical rationale of a progressively deflected aimpoint, that rationale is not at all realistic and not actually specified by the rules. What they are is mostly simple and somewhat balanced against achieving massive damage via the additive combination of many small hits.

Realistic implementation of rapid fire is basically applying the flyswatter principle: difficulty of hitting is determined by the size of the area you target, rather than the size of the target. The drawback is many of your shots will miss, and if don't use at least (size of area)/(size of target) bullets, the target might slip through holes in your flyswatter.

[Varyon]

Originally Posted by Plane

I'm not sure I'm understanding the benefits here though... if dice and DR are both multiplied by the same amount yet your RoF for determining hits goes down, then what's the advantage?

At such close range, the pellets haven't spread enough to justify any bonus to the chance to hit, hence lack of said bonus. Something you may be missing in all this, however, is that being at such close range changes the damage type from pi to pi++. This was later clarified by Kromm, and later still made it into print in Tactical Shooting. So, roughly speaking, being within 10% of 1/2D range deals half the damage, but all the Injury, of hitting with every pellet individually.

[Rupert]

Originally Posted by Anthony

Realistic implementation of rapid fire is basically applying the flyswatter principle: difficulty of hitting is determined by the size of the area you target, rather than the size of the target. The drawback is many of your shots will miss, and if don't use at least (size of area)/(size of target) bullets, the target might slip through holes in your flyswatter.

That's how 'rapid fire' is generally used in the real world. However there's another use, often found in RPGs and occasionally in the real world (mainly when using autocannon to kill armoured vehicles), where the objective is to hit the target many times, rather than to use a spread of shots to increase hit chances.

GURPS lumps these together, which works okay most of the time, but not so well with high RoF weapons with low Rcl (lasers, shotguns), which can effectively do both at once.

To fix this probably requires making two forms of rapid fire attack, one in which shots are spread out that grants a large hit bonus but only allows 1-2 hits per target within the volume attacked, and another that grants the possibility of multiple hits, but only a very modest increase in hit chance.

[Ulzgoroth]

Originally Posted by Anthony

Realistic implementation of rapid fire is basically applying the flyswatter principle: difficulty of hitting is determined by the size of the area you target, rather than the size of the target. The drawback is many of your shots will miss, and if don't use at least (size of area)/(size of target) bullets, the target might slip through holes in your flyswatter.

That analysis doesn't usually usefully apply to handheld weapons and sometimes fails to apply well to heavier weapons as well, though. It's not exactly wrong, but a shotgun or assault rifle isn't (typically) aimed to produce a beaten zone like a HMG - it's aimed at an individual target just as a single-shot weapon would be, but then discharges multiple projectiles. (Also in some cases the beaten zone is smaller than the target. Or the mechanically-generated beaten zone would be if you replaced the human shooter with a fixed mounting.)

[Anthony]

Originally Posted by Ulzgoroth

It's not exactly wrong, but a shotgun or assault rifle isn't (typically) aimed to produce a beaten zone like a HMG - it's aimed at an individual target just as a single-shot weapon would be, but then discharges multiple projectiles.

The beaten zone does not have to be an area effect as GURPS defines it. The reason you use a shotgun for bird hunting is because the shot pattern is larger than the bird, and for an assault rifle you are walking the shot across the likely target location (or if you aren't, it's not going to help your hit probability).

[Ulzgoroth]

Originally Posted by Anthony

The beaten zone does not have to be an area effect as GURPS defines it. The reason you use a shotgun for bird hunting is because the shot pattern is larger than the bird, and for an assault rifle you are walking the shot across the likely target location (or if you aren't, it's not going to help your hit probability).

I don't have the direct experience, but I'm pretty sure that you are absolutely in no way supposed to 'walk' a three-round burst anywhere.

More generally, it is distinctly unclear to me that you can effectively use the same mechanical approach to intentionally creating a beaten zone and de-facto creating a beaten zone when aiming for a point target.

[Rupert]

Three-round bursts were intended to increase hit chances because the movement of the rifle as it fired would create dispersion of the rounds. So they were 'walked' by recoil.

The belief was that after three rounds the shooter would be so far off-target that any extra rounds would just be wasted, so putting in a burst limiter would save ammunition without reducing the effectiveness of the burst. Soldiers were trained to fire 3-5 round bursts anyway (for the same reason), so the burst limiters were essentially a way of getting short bursts from soldiers who might not've been as well-trained in fire discipline as their commanders would've liked.

[Polydamas]

Originally Posted by Rupert

That's how 'rapid fire' is generally used in the real world. However there's another use, often found in RPGs and occasionally in the real world (mainly when using autocannon to kill armoured vehicles), where the objective is to hit the target many times, rather than to use a spread of shots to increase hit chances.

Isn't close-ranged rapid fire with semi-automatic weapons and revolvers often meant to score multiple hits, such as the good old "two in the chest and one in the head?" And a close-ranged handgun shooting is probably the modal use of a firearm in GURPS.

Pump-action shotguns also combine the "fire hose" type of rapid fire with the "spray can" kind. A bursting cannister behaves differently than a burst from an electric gatling gun, even if both put the same number of rounds downstream in a second.

[Rupert]

Originally Posted by Polydamas

Isn't close-ranged rapid fire with semi-automatic weapons and revolvers often meant to score multiple hits, such as the good old "two in the chest and one in the head?" And a close-ranged handgun shooting is probably the modal use of a firearm in GURPS.

In theory, sometimes. In practice it's usually "shoot until they stop", and that's usually poorly aimed fire that goes all over the place, sometimes including into the actual target.

[Varyon]

Originally Posted by Polydamas

Isn't close-ranged rapid fire with semi-automatic weapons and revolvers often meant to score multiple hits, such as the good old "two in the chest and one in the head?" And a close-ranged handgun shooting is probably the modal use of a firearm in GURPS.

I suspect that isn't really meant for scoring multiple hits, honestly. You shoot two bullets at the chest to make it more likely at least one of them will hit*, and the shot to the head is because a) that's where recoil naturally "walks" your aimpoint to anyway and b) if a hit to the chest didn't stop them, another probably won't either, so you need a CNS hit. Personally, I wonder if going pelvis->chest->head might not be better (it's still in the natural direction for recoil, and has the first shot have a good chance of knocking them down by functionally crippling their legs, the second shot being one with a higher hit chance that still has a decent chance of stopping the target, and the last being a go-for-broke option. But I assume there are good reasons to go chest->chest->head.

*GURPS doesn't model this that well, given you need RoF 4+ to get any sort of bonus. It does have it to a small degree, however - firing with RoF 2-3 means you have a chance of scoring multiple hits, which makes it more difficult for the foe to Dodge all of them. Honestly, I think it would smooth out the progression if you did +1 at RoF 2, +2 at 3-5, +3 at 6-10, +4 at 11-20, +5 at 20-50, +6 at 51-100, and so forth, for +1 to hit per +2 SSR to RoF. It lets lower RoF accomplish something, is consistent throughout the entire progression, and - most importantly IMO - means you can generate the table simply from the SSR progression rather than having to look it up constantly.