Originally Posted by Tcheno
So usually you go down a size over the stock ones?
no, say you have a #13 o-ring / x-ring. you can get away with a slightly smaller OD (or larger ID depending if it was your bolt can ring) so you could have that on the bumper sail and get away with less friction. but you would not be able to go all the way to #12 or #14.
the way rubber rings are made is pretty basic, they are all different sizes by very slight amounts so you need 5-10 per ring you are trying to replace to get that ideal no stick feel. my bolt sticks using dye's o-rings and fires fine though so i'm not willing to really mess with it. just saying that x-rings are a good thing in other industries.