[HT][UT] The SM of guns

[DemiBenson]

So for the purposes of adding armor or stealth features (mainly from UT), what is the SM of a gun?

Obviously this depends on it's weight, whether it's a longarm or a pistol or a rocket launcher, etc. But does anyone have a rule of thumb or a rough formula?

[sir_pudding]

Originally Posted by DemiBenson

Obviously this depends on it's weight,

Mass based SMs is just a rule-of-convenience for Spaceships. Size Modifier for weapons uses the rule on B400

You are at -5 to hit a reach “C” melee weapon (e.g., a knife) or a pistol; -4 to hit a melee weapon with reach 1 (broadsword, mace, etc.)
or a medium-sized firearm (e.g., a carbine or sawed-off shotgun); and -3 to hit a melee weapon with reach 2+ (spear, greatsword, polearm, etc.) or a rifle.

[vierasmarius]

I suspect that there's some correlation between a weapon's Bulk and its SM, but it's not immediately obvious what that is. Based on the Blaster & Laser Design article from Pyramid 3/37, Bulk is derived from the square root of weight, modified for the configuration (rifle/cannon, pistol, holdout), maxing out at Bulk -10. SM is based on the longest linear dimension, and thus corresponds roughly to the cube root of weight for creatures and vehicles; this may not hold true for weapons in the hand-held range.

Per the article, Holdout guns range from Bulk 0 (<0.25lb) to -1 (1 lb), Pistols are -1 (≤1 lb) to -3 (4 lb), Rifles are -3 (5 lb) to -6 (15 lb), and Cannons are -6 to -10. Based on weight alone, 16 lb is SM -2 (10 HP), 5 lb is SM -3 (7 HP), 2 lb is SM -4 (5 HP) and a 1/2 lb is SM -5 (3 HP). I suppose you could say that SM is roughly 0.5 * (10 + Bulk), rounded down. It would be more precise to calculate from the weight of the individual gun, and even more precise if you know it's actual length (which is the case with everything in HT, but generally not in UT).

[DemiBenson]

Originally Posted by sir_pudding

Mass based SMs is just a rule-of-convenience for Spaceships. Size Modifier for weapons uses the rule on B400

Well, not just a rule of convenience - a 2000 pound cannon is going to be a lot bigger than a 2 pound pistol. But it's the fine details that get lost in such a rule.

And the bit on B400 doesn't actually say what the size modifier is. If you go by the size of people's body parts to determine to-hit penalties, they don't match all the ones in the handy charts and tables. e.g. my torso is only 26 inches tall (which, IIRC, should be SM-3), but still considered a SM0 target, which gets no penalty to hit.

Hence my original question.

[DemiBenson]

Originally Posted by vierasmarius

I suspect that there's some correlation between a weapon's Bulk and its SM, but it's not immediately obvious what that is. Based on the Blaster & Laser Design article from Pyramid 3/37, Bulk is derived from the square root of weight, modified for the configuration (rifle/cannon, pistol, holdout), maxing out at Bulk -10. SM is based on the longest linear dimension, and thus corresponds roughly to the cube root of weight for creatures and vehicles; this may not hold true for weapons in the hand-held range.

Per the article, Holdout guns range from Bulk 0 (<0.25lb) to -1 (1 lb), Pistols are -1 (≤1 lb) to -3 (4 lb), Rifles are -3 (5 lb) to -6 (15 lb), and Cannons are -6 to -10. Based on weight alone, 16 lb is SM -2 (10 HP), 5 lb is SM -3 (7 HP), 2 lb is SM -4 (5 HP) and a 1/2 lb is SM -5 (3 HP). I suppose you could say that SM is roughly 0.5 * (10 + Bulk), rounded down. It would be more precise to calculate from the weight of the individual gun, and even more precise if you know it's actual length (which is the case with everything in HT, but generally not in UT).

Thanks. 0.5 * (10 + Bulk) sounds like a fine formula - it uses mass as the first order approximation and takes into account shape (beamer vs pistol vs longarm). And one can even add +/-1 for unusually long or stubby ones.

[sir_pudding]

Originally Posted by DemiBenson

Well, not just a rule of convenience - a 2000 pound cannon is going to be a lot bigger than a 2 pound pistol. But it's the fine details that get lost in such a rule.

It is just a rule for Spaceships. SM is otherwise based only on size. That 2000 pound cannon and a full scale papier-mâché copy of it will have the same Size Modifier, mass has nothing to do with it.