Cricket pressure.

So I bought a Cricket .25 and absolutely love it. It was tuned by Rowe and then the owner sold it to me. Here is my question
When filling, with a 4500psi tank, the gun will only fill to 220 sometimes 240 bar. No higher,even though its a 300bar fill max. Ive filled this gun a dozen times and 90% of the time can only get it to 220. This is verified by the gauge on the gun and the tank. I get good consistent shot counts so its not a real issue, but for the life of me It drives me nuts I cant get to 300. What am I missing. Thanks for the input.
 
I would guess that its the valve on your fill tank that is preventing you from filling to the higher pressures. It doesn't make much sense to me, but when I am filling my RAW it will slowly fill to about 205 BAR, and then stop until I open the tank valve a little further. You would think that if the valve is open at all the higher pressure in the fill tank would push the air through whatever opening is there, but that doesn't seem to be the case for some reason. The Joe B slow flow valves have a little plastic pin in them that restricts the air flow. Per Joe B, some of the older ones were manufactured to a slightly different spec than what Joe had asked for and the pin can restrict the air flow too much. I had to take mine apart and clip the pin off shorter to allow additional air to flow through the valve. If you have an older Joe B slow flow valve you may have the same situation. 
 
"Ginuwine1969"First you should never fill the gun to 300 bar (NEVER). Anything over 220 bar on my Cricket .22 is a waste of air according to Ernest so i fill it to 205. I believe anything over 250 causes undo stress on your gun, the seals, and the air tube, that's what i've been told.

Help me understand this. How is it wasting air in a regulated gun?
 
I would guess, and this is only a guess, that if the regulator uses the traditional bellvile washer setup that maybe they can't handle more than 230-250 and let the air rush by? Of course that begs the question if the valve is set up to operate with a 300bar fill why isn't the regulator? And why have the valve ported/sprung to be able to work at that pressure if the regulator isn't? If this is the case then the valve should be reworked for use at acceptable regulator pressures to produce tighter spreads and greater shot count?