How to calculate fantasy claymore mine

[Lameth]

In my fantasy game two of the PCs are modern soldiers brought over with some tech. In my current plot they have found the area of a planned massive ritual of three faerie hags to “undo man”. In truth is a ritual to cease human fertility within thousands of miles radius. They have decided to ambush them before the hags get to the ritual by planting three claymore mines in strategic places I the ritual ruins and then to get them all at once. In anticipation of this they used their various skills, improvisation, and some mystical help to replace the metal balls in the claymores with 100s of small cold iron pieces to be used as fragmentation to rip and shred the hags. On my world cold iron does on average 1d6 extra damage, or more, and also drains 1 or more fatigue per hour if the creature is constantly in touch, surrounded or bound by it.

How would this work as far as damage? And how do you figure out claymore damage in the first place ? if the three hags are hit by all three, let alone one of them how much would that be? Thoughts? Thx

[Nereidalbel]

Claymores can be found on pg189 of High-Tech. Just add the extra 1d per hit to the hags, and make sure no friendlies are in the murder cone.

[Culture20]

I assume “cold iron” is some magical substance, otherwise the iron will be warm from the detonation.

[mr beer]

Nereidalbel has it covered I think. My question marks would be over the payload and the explosive charges.

Are the iron balls equivalent to the 700 steel pellets used in an actual claymore? The rules provided in the entry in High Tech allow you to dial up or down for more or fewer balls. If the balls are smaller, they should do less damage I think, more if larger.

The actual claymore uses 1.5 lbs of C4, so if the fantasy version uses gunpowder for example, it will require a larger charge to be effective. Also, C4 is a high explosive and I don't know if that makes a difference, whether the same effect will be achieved or not with gunpowder. Still, gunpowder obviously can be used to propel metal to kill so I don't see why not.

Say each hag is in the cone of 2 claymores at 20 yards distance, that's skill 9 + 9 - 6 = skill 12. Each degree of success adds 1 hit. Each hit is for 2d (0.5) + 1d. If they don't know about the attack, they cannot Dodge. If they can Dodge, they can drop for +3. Seems to me if they don't get to Dodge, it's likely they are going to get shredded, if they can Dodge it might go either way.

[starslayer]

Lack of high explosives would basically make a claymore design useless, that rapid expansion is crural, fortunately he mentioned the PCs brought tech with them.

The lack of hard steel for the projectiles is likely going to be huge but not insurmountable, I would full on half damage.

[mr beer]

Originally Posted by starslayer

Lack of high explosives would basically make a claymore design useless, that rapid expansion is crural, fortunately he mentioned the PCs brought tech with them.

The lack of hard steel for the projectiles is likely going to be huge but not insurmountable, I would full on half damage.

If high explosives are required for a claymore to work, then I guess a gunpowder equivalent would need to be a sort of disposable cannon design? Kind of like a giant shotgun shell but with stronger materials at the base and cylinder.

Would the difference between iron and steel really be that great? I sort of assumed at those kind of speeds a ball of reasonably dense metal is going straight through someone regardless of the hardness.

[Icelander]

Originally Posted by starslayer

The lack of hard steel for the projectiles is likely going to be huge but not insurmountable, I would full on half damage.

I very much doubt that the difference between iron and steel projectiles would make much of a difference, if any, to terminal ballistics in human flesh. The hardness of the alloy might matter when penetrating armour made of certain materials, but not really for unarmoured targets. And I don't believe that any likely difference in density or hardness between TL3 iron and TL7 steel would be enough, particularly with completely round penetrators, to halve the effective penetration against common TL3 armour, assuming similar velocities.

[The Colonel]

Originally Posted by mr beer

If high explosives are required for a claymore to work, then I guess a gunpowder equivalent would need to be a sort of disposable cannon design? Kind of like a giant shotgun shell but with stronger materials at the base and cylinder.

Would the difference between iron and steel really be that great? I sort of assumed at those kind of speeds a ball of reasonably dense metal is going straight through someone regardless of the hardness.

The pre modern version was called a Fougasse ... it's not exactly the same but is at least similar.

[starslayer]

Originally Posted by Icelander

I very much doubt that the difference between iron and steel projectiles would make much of a difference, if any, to terminal ballistics in human flesh. The hardness of the alloy might matter when penetrating armour made of certain materials, but not really for unarmoured targets. And I don't believe that any likely difference in density or hardness between TL3 iron and TL7 steel would be enough, particularly with completely round penetrators, to halve the effective penetration against common TL3 armour, assuming similar velocities.

The issue is that a claymore mine relies on the ability of the projectiles to all but instantly absorb a lot of energy and reflex from that. If the projectiles deform they will loose a lot of that initial energy impulse, then have absolutely wonky air ballistics, and then be flat when they impact a target.

Since damage in gurps is roughly a function of how much RHA steel will be penetrated by the attack I absolutely can see this contributing to a full halving of the damage. Playing with an armour multiplier instead may be applicable, but the net effect should be roughly the same; the projectiles will only go through half the thickness of RHA steel.

[Icelander]

Originally Posted by starslayer

The issue is that a claymore mine relies on the ability of the projectiles to all but instantly absorb a lot of energy and reflex from that. If the projectiles deform they will loose a lot of that initial energy impulse, then have absolutely wonky air ballistics, and then be flat when they impact a target.

Since damage in gurps is roughly a function of how much RHA steel will be penetrated by the attack I absolutely can see this contributing to a full halving of the damage. Playing with an armour multiplier instead may be applicable, but the net effect should be roughly the same; the projectiles will only go through half the thickness of RHA steel.

The 1/8" steel balls already deform in the explosion of an M18 Claymore. They're made from soft steel, because the harder steel balls initially tried would spall and fragment, but soft steel happily (and initially accidentally), formed into fairly aerodynamic shapes by the explosion.

TL3 absolutely has the technology to make soft steel. The PCs are relying instead on 'cold iron', but assuming it's anything like the iron used for typical nails, horseshoes or cheap armour plate, it wouldn't be very far off from the soft steel used it the balls for the Claymore mine.

More relevant may be the lack of epoxy to encase the steel balls in, but that only costs you a smidgen of velocity (3,775 fps vs. 3,995 fps). If the PCs were using black powder instead of more modern explosives, of course, that might have a serious effect on velocity, even if they use more explosives to compensate for lower REF.