Crosman Optimus .177 Loss of power

Hello,

I bought a Crosman Optimus .177 a few months ago. My grandson and I were using it a few times, so there was no heavy use at all. Just a few days ago I tried it and noticed that it has lost considerable amount of power. I took it apart and found nothing significant. No broken spring, no scratches inside the cylinder, seemed to have plenty of lubrication and the piston seal looked fine. I noticed though, that the piston did not move in the cylinder as freely as I thought it should. Also, I did not see any vent hole that is commonly used to limit air pressure. Is it then possible that Crosman is using a combination of seal and lubricant to de-tune the gun? If not, what might cause the loss of power I am seeing with this relatively new gun? The power loss happened over a long weekend.

Thanks for any advice/opinion you might offer.
Loden

May be detuned using a cut spring and/or a longer piston, piston vent is only one way that may be used. No seal/lubricant methods are used to detune. Your spring has compressed beyond where it should and/or your piston seal is leaking ('looks fine' doesn't necessarily mean anything if it has worn).

Maybe I should have been clearer in my initial description of the problem. The gun had been working fine and I used it a few times after I bought it. The loss of power occurred recently over a few days. Thanks for your opinion, though...
Loden

Doesn't change my original statement.