I must ask, however, where to I place the shim(s)? Are they placed on the barrel hook or on the action pin?
Between Them!! Yeah! Yeah! I know that is a smart alec answer, but is essentially what you have to have. Seriously, you will have much better results trying to keep the shim in the bbl hook than on the pin. If you don't take the bbls off on a regular basis it doesn't really even "Have" to be attached. It is more convienient to put a drop of adhesive under it, or if a more permanent type of mat'l is used it can be soft soldered in.