Originally Posted by cpgop
Oh no. How come they damage the hop up rubber?
Some very cheap BBs often have seams that can tear your rubber hop up sleeve as well. The sleeve serves two purposes, it seals the barrel and nozzle together (the BB gets pressed through it by the nozzle), that can tear resulting in high drop in velocity. It also puts variable (user adjustable) pressure on the top of the BB to give it the backspin, this is a thicker chunk of rubber so it's less likely to rip or tear from a seam on the BB, but will still show damage after many crappy rounds passing by it.