[lurkingknight]

you have to be extremely lucky to have a barrel that you just put the patch in and go.. so far I've not found a barrel that any patch fits perfectly in terms of barrel intrusion. Also after sanding it to fit with 0 intrusion and being able to drop a bb down the barrel, once installed that sucker overhops everything to the moon, so I've had to sand the inner radius on every install I've done so far. This is where patience and the futzing come in.. you need to sand, assemble, test... pull it apart and rinse and repeat till its' right.