Shrapnel, Beehive, and Chance to Hit

[WinSPShrapnel]

Hi,
I'm a newbie to GURPS and I'm setting a campaign in the late 19th Century. I'm looking at the rules for shrapnel and beehive rounds (HT173) and I'm confused on the rules for the chance to hit and the margin of success. For example, with shrapnel, I could treat it like a giant shotgun, but that makes little sense because a) that's not how shrapnel and beehive shells work in real life and b) the existence of canister shot in High Tech, which behaves exactly like a giant shotgun in both GURPS and IRL, implies that different rules are in play. I could treat it like ordinary fragmentation, but shrapnel and beehive have a fixed RoF (i.e RoF 1x270 for the Mle 1897 on HT140) for its attacks, as opposed to fragmentation which has effectively unlimited projectiles but a flat skill check of 15, with Rcl 3 and range penalties applying. Furthermore, how many hexes would a shrapnel shell cover, since it is roughly a cone of shrapnel distributed over a large area? If so, should I consider the RoF for the shrapnel to be the max RoF for everything in the area, or should I break down to an evenly distributed RoF per hex?
So, to reiterate:
What should the value of the check to hit the target be for the shrapnel proper, rather than just the shell, what is the size of the area a shrapnel shell effects, and what is the RoF per hex if so?

[jason taylor]

Originally Posted by WinSPShrapnel

Hi,
I'm a newbie to GURPS and I'm setting a campaign in the late 19th Century. I'm looking at the rules for shrapnel and beehive rounds (HT173) and I'm confused on the rules for the chance to hit and the margin of success. For example, with shrapnel, I could treat it like a giant shotgun, but that makes little sense because a) that's not how shrapnel and beehive shells work in real life and b) the existence of canister shot in High Tech, which behaves exactly like a giant shotgun in both GURPS and IRL, implies that different rules are in play. I could treat it like ordinary fragmentation, but shrapnel and beehive have a fixed RoF (i.e RoF 1x270 for the Mle 1897 on HT140) for its attacks, as opposed to fragmentation which has effectively unlimited projectiles but a flat skill check of 15, with Rcl 3 and range penalties applying. Furthermore, how many hexes would a shrapnel shell cover, since it is roughly a cone of shrapnel distributed over a large area? If so, should I consider the RoF for the shrapnel to be the max RoF for everything in the area, or should I break down to an evenly distributed RoF per hex?
So, to reiterate:
What should the value of the check to hit the target be for the shrapnel proper, rather than just the shell, what is the size of the area a shrapnel s hell effects, and what is the RoF per hex if so?

I think beehive is a brand name for a type of canister that uses flechettes instead of the musket ball sized rounds of the eighteenth century. Beehive did not come on the scene until after WWII.

Also you are making no distinction between shrapnel and canister. Shrapnel today means "junk flying everywhere" but when it was invented it meant rounds of grape or canister (I can't remember which) placed in an explosive shell to extend range. Canister is simply fired out the barrel of a cannon with an effect similar to that of a machine gun at close range.

[WinSPShrapnel]

You're right, beehive is a separate kind that was invented after WW2, I'm just curious because the rules for both shrapnel and beehive seem to be similar. Also, I do make a distinction between shrapnel and canister in the section where I talk about why I cant treat shrapnel like a giant shotgun. I am aware that shrapnel projectiles are dispersed in a kind of proto-airburst shell. That is the crux of the question: I am confused as how the rules for this differ from the standard fragmentation rules, which they clearly do.

[jason taylor]

Originally Posted by WinSPShrapnel

You're right, beehive is a separate kind that was invented after WW2, I'm just curious because the rules for both shrapnel and beehive seem to be similar. Also, I do make a distinction between shrapnel and canister in the section where I talk about why I cant treat shrapnel like a giant shotgun. I am aware that shrapnel projectiles are dispersed in a kind of proto-airburst shell. That is the crux of the question: I am confused as how the rules for this differ from the standard fragmentation rules, which they clearly do.

I'm guessing that you should use canister as a base and then to convert to shrapnel, increase the effective range (because it has a shell to deliver the attack) and decrease the damage (because fewer rounds can be carried in a shell then straight out of a cannon).

[WinSPShrapnel]

There are already rules in High Tech for the damage and range. What I want to know is what the base dice number required to hit for these attacks is, how does it attack multiple hexes if at all, and if it does effect multiple hexes how to divide the shots between them.

[Pursuivant]

Originally Posted by WinSPShrapnel

There are already rules in High Tech for the damage and range. What I want to know is what the base dice number required to hit for these attacks is, how does it attack multiple hexes if at all, and if it does effect multiple hexes how to divide the shots between them.

Looking at the High Tech rules, I don't think that the authors did a good job of explaining the difference between explosive projectiles that burst at a distance from the gun and multiple projectile rounds that turn a cannon into a giant shotgun.

For shrapnel from explosions, start with a base chance to hit of 15, modify the roll by target Size, Posture, and Range from the blast center. For airbursts, ignore posture. Basic blast and shrapnel damage is divided by 3 x yards. Assume that the explosion and shrapnel affects a sphere unless there's solid cover that blocks damage in a given direction. For ground bursts, this means the blast affects a hemispheric volume but for simplicity you can just use area of the blast diameter.

For "giant shotguns" start with the gunner's skill, then modify by number of projectiles in the shot (listed by gun type), range from the gun to the nearest target, then target Posture and Size. The gunner's margin of success vs. the weapon's Rcl stat determines how many projectiles hit after the first, hence damage to a given target.

If there other targets beyond the nearest target, assume that any projectiles that didn't hit the first target continue downrange. IIRC, they get treated as wild shots that hit on 9 or less on 3d. If any of the projectiles hit, subtract them from the group, apply damage to the target, and roll again to see if the remaining projectiles hit the next target in line.

The assumption is that you don't get serious spread of projectiles until some distance from the gun, so all the projectiles in the group fill a single hex. They only count as a single shot if the nearest target is within 10% of the gun's 1/2D range. In that case, both damage and target DR get multiplied by half the gun's normal RoF modifier.

If I'm reading the High Tech rules for shrapnel shells right, the shell remains as a projectile until it reaches a given range and then explodes, creating an airburst explosion (with explosive damage ignored) and shoots metal projectiles downward and forward from the point of the explosion, creating a multiple projectile at the burst point.