Simon if you are looking at reducing fps spread look at the barrel first, load a pellet in the normal way then shine a torch down the barrel from the front, if you can see any light around the pellet you wont improve your spread without re-machining the pellet entry. The gaps will allow a varying amount of air past the pellet before it starts to inflate the skirt and seal. A total seal will ensure the same quantity of air delivered from the reg and firing mechanism will stay behind each and every pellet.
At the moment you are trying to measure how much water a bucket holds while it is leaking! Stop worrying about putting the same amount of water in the bucket and fix the leaks first!
HFT, for people with only 2 buttucks!
VooDoo TwoTwo The next chapter.