Ret_Marine:
Lodgewood Mfg. in Wisconsin is a very good source of parts for many black powder military firearms - here is a link to their page listing original parts for the P'53 through P'62 Enfields and the Snider conversions (... they also have a separate page listing reproduction parts ....)
http://www.lodgewood.com/original enfield.htm
Scroll down the list to near the bottom, where you'll find part #SN-52 ("Firing Pin, Snider-Enfield" for $10.00) and, right at the bottom, #SN-52S ("Spring, Firing Pin" for $5.00) ...
By the way,
THE forum site for all things to do with the world of the Snider-Enfield, Martini-Henry, and all other things related to obsolete British firearms and militaria, is British Militaria Forums -
http://p223.ezboard.com/bbritishmilitariaforums
While GunBoards is certainly one of the best firearms forums on the internet (I am a member and daily visitor), as a new Snider addict (.... Warning: more Sniders, if not Martini-Henrys and other exotic British Empire smokepoles, are likely to follow your first acquisition ....

) you should sign up there as well!