i use the filter tip meathod cos mines a bsa with a roll breach.
i`ve been told off on here before for suggesting it.
apperently you dont get that buffer before the piston hits the transfer port.
i had mk1 about 5 years and when i put a new spring in there was nothing wrong with the piston seal.
as long as you remember to find something to cushion the barrel against, no probs. i.e get an old catalogue put the barrel about 5mm away from it and you should get the same effect on the piston as firing a pellet.
my measurement might be wrong as i work in old money, but you get my drift.