> I buy 11/32" shafts and cut them in half for my 75# crossbow I
> usually spine the shafts at 50 to 60 lbs.
Spine isn't relevant for crossbow bolts.
I make either short bolts or long bolts depending on the distance I am planning on shooting. Longer bolts for shorter distances and short bolts for anything 60 yards and over. Same with fletching as I do longer fletching for shorter distances.
One universal thing I do is use the heaviest tip I can as for me I have found this tightens my groupings. I personally like 190 grain tips.
Another thing that I do depending on the material my stock is made of is lubricate the shooting deck. Raillube is great for wood but for a synthetic surface I use something like ArmorAll. Amazing how many ft/sec you gain.