diffing in to the Crossman M4-177

[pharoah007]

found a few things I would like opinions on,

First here is the exhaust hole in the piston stock....

Here is the exhaust hole in the valve, the rubber o ring's ID matched the ID of the hole in the barrel support (shown above)



I remove the o ring and find this curious metal washer between the o ring and the valve exhaust port



The actual hole in the valve is a lot bigger withut that washer. any particular reason it is there? My limited knowledge of airguns tells me this is robbing the rifle of power. If so do I just remove it, or does the washer have some function...and thus I would need to leave the washer, drilling out the center of the washer to match the hole in the valve.

Last I find this curious hole, just below where the valve stem sticks out of the valve....what is it for....it this to vent pressure and "de tune" the rifle?




EDIT subject should read M4-117 not M$-117