[Icelander]

I know that there isn't a weapon design system in existence. I know that what I'm asking will more properly be answered if and when we get one.

But I need at least a provisional judgment call on it now.

I'm attempting to link crossbow size, weight and power with the poundage needed to draw it. That way, crossbows might be closer to reality than the current version.

Clearly, the more powerful a crossbow is, the stronger its construction needs to be. Some of that can come from better materials, but the most common method will always be a larger and heavier prod.

In addition, the longer the prod/lanth is, the more efficiency we get. That means a bow with a very small prod needs a very high draw weight to get the same initial velocity as a prod with longer limbs. It's therefore practical to have the prod of a dedicated war weapon be as wide as a man can easily use.

I can find the weight stats for crossbows of a given poundage in historical sources. I can also find their dimensions. Their capabilities can be estimated from testing data and the GURPS ST damage rules (which are faulty at high levels, but I'll use nonetheless to retain compatibility and relative power with other muscle-powered weapons).

But Bulk and ST for missile weapons do not correspond to any real world number that I can research. The best I can do is compare to similar weapons and guesstimate.

So, GURPS gives a Crossbow weighting 6 lbs. Bulk: -6 and ST: 7†. A Composite Crossbow weighting 7 lbs. has the same Bulk, but ST: 8†. A Repeating Crossbow of 10 lbs. is Bulk: -5 and ST 7†. A Pistol Crossbow weights 4 lbs. and is Bulk: -4 and ST: 7.

My questions are these:

a) What are the dimensions of these weapons?
b) How much does weight have to change in either direction before ST changes?
c) How much does Bulk change with increased size?

In other words, what Bulk and ST is a 18 lbs. crossbow with a lanth 4' wide? And so on and so forth.