I have most parts but i have a few queries before fully assembling.
Assembled

Parts

Stem

'A' = I wish to make a piston to surround the bolt (probably out of nylon) so it is flush with the ID of the (hammer side) nipple. I have access to a lathe but i cannot find any nylon rods. Where can i get them other than Mcmaster?
'B' = I need to attach the washer to the bolt for the spring to push against but glueing it on seems a pretty scrappy method. Any suggestions?
Any overall suggestions/problems would be much appreciated.