Quote Originally Posted by nick_mantis View Post

What is the likelyhood of being able to get a replacement piston for an HW55?
Having rummaged through my spare piston box this morning I have found a piston from a different manufacturer that would work in a HW55 --- the early SMK B2 piston.

The early leather sealed B2 piston and in its converted to synthetic seal form will fit the HW55 with the minimum amount of work --- the only downside is that it will give 8mm less stroke than the HW55 piston, but at 6ftlbs that shouldn't matter.

NOT this late B2 piston :-

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The B2 synthetic converted piston would need machining down to sub 25mm on the flared front and rear sections as it's designed for a 25.4 cylinder, the cutout in the latchrod for the trigger sear would need deepening by 1mm and the seal would need changing for a TX200 one --- that's about all you'd need to do for an 8mm short stroke piston.

Now if you wanted more stroke, you could machine off the welded on SMK synthetic seal seal adaptor and move the seal back to gain 5.5mm of stroke --- obviously the cocking lever slot in the piston would need extending rear wards to suit.



The only modification needed to the gun for this to work is the drilling out of the latchrod hole in the back block to 10mm.





All the best Mick