Geezer here: Inch-pounds is a figure that is supposed to represent the amount of energy stored in a bow... it says nothing about the efficiency of the bow, which varies by a huge number of factors. The system is simple: measure the length of draw in inches, from string at rest to the lock. Measure the draw-weight in pounds at the lock. Multiply the two together. So a 10 inch power-stroke, multiplied by 60 lb. of draw will get you 600 inch-pounds.
To make things a little more difficult, SCA limits actual draw-weight to 75 lb. I've never been given a satisfactory reason for that one... theoretically there should be little difference between 60 lb. at 10 inches or 100 lb. at 6 inches, but that's SCA for you.
SCA combat bolts nowadays use 1/4 fiberglass rod, with an 1&1/2 inch diameter plastic and rubber head, specifically made for the purpose (one variety is called 'baldar-blunt' ) and a special fletching unit which can be used for either crossbow bolts or handbow arrows, called an 'asgard fletch' Both are made by an SCA guy in Florida who is tooled up to make such.
In former days, we made our combat bolts up out of wood, padding, foam and the like. Those bolts were substantially lighter and flew better if properly constructed, but the newer 'baldar-blunt' bolts have the advantage of being almost indestructible and very consistent from bolt to bolt. On the whole that makes the average SCA archer a better marksman than previously. If you do a web search under 'baldar blunts' you'll probably find some pics.
Does that help? Geezer