weapon upgrade removal?

if I upgraded my bow with a grip, is there any way to extract the grip to use in on a different bow, or is it stuck on it.
Also, where can u get upgrades to ur weapons such as strings or grips?
thx, for any help

You can use an expert salvage kit to get the upgrade back, though that doesn't necessarily mean it will work or that you will get the desired upgraded (if there is more than 1).

You can get upgrades by identifying blue, purple and gold weapons from loot and salvaging them like above, or by purchasing them from other players.