recently gave me trusty old hw77k an overhaul,looked on chambers website & noticed early 77's had 25mm piston seals & later ones 26mm. tried to order relevant spares but couldn't as main man's out of action so got my bits from another well known gunsmith who when questioned by yours truly about early & late hw77s piston seal size differences told me they were all the same so i took his word and purchased the gear.however when comparing to old washer it did look 1mm bigger and seemed to be tighter in comp tube will this make a difference to performance? or am i turning into an airgun nerd after all whats a 1mm between friends?