I don't see the back cap in the pictures,you should get it drilled or a new one so you have a rear velocity adjuster.
you have the spring and hammer too?
that's a auto trigger set up/aka slam fire.you might need to tune/time it a little.
it should fire when the bolt just closes all the way.
here's a good cheap way of making a valve tool DIY Valve Tool
disassembly PGP Non-Cartridge Valve Disassembly
you can run that gun on 12 gram co2's instead of the CA set up...
BTW there's a sheridan section in the armory