Bolt weight to prod poundage

It is often said that to use a lighter bolt in a crossbow than the recommended weight of bolt will cause damage to the prod limbs. What is the correct bolt weight for a 50lb crossbow and so on. Tried to find out the weight but just come up with juck crossbow pistols with flimsy plastic bolts.

Egon Harmuth's "Die Armbrust" had a figure for bolt-weight: a percentage of the prod-weight.... I think that was for steel bows, and might vary a lot for fiberglass, wood, or composites.
For my lightweight 70 lb. aluminum alloy bows, I recommend 5/16 in. cedar shafts, @ 15 inches long and 70 or 100 grain points and two 3 inch feathers.  For my 125-150 lb. steel bows, I use 11/32 cedar shaft, 15 inches, and 125 grain points.  Over @ 150 lb. I recommend going to 150-160 grain points, and possibly 3/8 in. ash shafts. 
If your bolts are too light, you waste a lot of power and may damage the prod or bowstring.  The lighter the bolt, the closer you come to dry-firing
.  If your bolts are too heavy, you lose velocity, and end up with a very round trajectory.
You can also vary bolt-length.  Medieval bolts stored away in European armories tend to be about 15 inches long.... (vary from 12 to 18 inches)  Very short bolts will fly faster, but will be less stable, and more important for modern shooters, you'll end up burying your bolts into the target far enough to rip the fletching off. 
Third point, since nobody here has mentioned it lately: For best flight, the balance point for your bolts should be somewhere between 1/4 and 1/3 of the bolt-length back from the front. Moving the balance point further back will result in instability.  I hope that helps.  Geezer.