What will adding a shim do?

[Moats]

Will it change velocity...

Will it make the bolt hit harder, or does it vent the air soon/later.

Thanks Guys....See-ya

[magman007]

it makes it vent earlier i believe

[BlackVCG]

Yes, it makes the bolt vent earlier, but it also can make it leak constantly depending on how many shims you already have installed. if the bolt doesn't lock up on a ball when it pinches it and it doesn't leak constantly regardless of which carrier size you use, then there's no need to change the number of shims.