Last night after shooting a few rounds, I pumped up my .25 Mrod.
Checking the pressure later it was down 500 lbs. An hour later it was down another 500 psi. By this morning the gauge read 0.
So, thinking it was the check valve on the fill end. Suspicion fell on the check valve because after shooting, the rifle held pressure for about 1 1/2 hours. Then started leaking after topping off the pressure.
Having never taken it apart before I was curious to see the inner workings.
The check valve is a stem with an 0 ring inside the quick detach nipple. I took it apart wiped the clean grease off of it. And with some advice from D-RIG used silicone grease on the 0 ring for re assembly.
310 strokes of the pump later it has 2500 psi showing on the gauge. I have been giving 50 or 70 pumps at a time. The valve on the chamber end must not be leaking, but really will not know if the check valve is holding until I disconnect the pump.