If you increase the valve capacity you are going to have to pump it more to achieve the same pressure. And you probably won't capitalize on those gains without going to a longer barrel.

You missed modding the plastic parts that the spring pushing apart seals the valve. They can be shorter and beveled. And yes you will have to pump more and have a longer barrel. But from owning a Model One and seeing how much you can get from a half size valve my next 13XX valve mod will be decreasing the valve volume.

I honestly do not recommend doing the thinning of the valve stem.

Some of the advice here is good but to be honnest ive done alot of these mods and DIY mods work but break faster. I did alot of this and buying parts made a better diffrence than diy tunes. Good vid tho. Juat hope it worked better than before. A vid of the new power would make it legit.

cant i just plug te holes in the valve thats what i did to my sheridan and it worked great

found the CDN. spec. piston is further de-tuned with 1mm vent above the plunger hole .

wow what a great vid on how to fuck up and bodge a crosman valve whilst high as a kite

Very informative! Thank you!

All you are doing is increasing storage or volume, pressure is still the same, what Need's to be done is modifi the pump mechanism to increase pressure then you are actually doing something, opening the port decreases pressure what you are doing is good but if you get that pressure up you got your self a good shooter

If you want to increase the inside diameter of the air chamber wouldn't it be best to use a reamer or maybe a drill bit would be sufficient needs to be very precise and and smooth

Bhaloi, less space , but same volume of air making the air more compressed in the small encatchment, and sudden release of normal air contained to lesser space accomodated pressure from will exert more power? But the stable tactics is to use more air under utmost pressure utilizing more space but over exploiting the bigger space, cause big space can accommodate high air content and more air can generate more pressure regardless of the cabinet / chamber space . Its like say 1 cc cylinder can store 1cc air , but for 5 cc cylinder its not directly proportional but exponentially kind of proportional directly, ie it will contain 8-9 cc of air, i mean considerably more air that space provided, and this properties need be exploited

This sounds good and all but I am still looking for proof. Has any one did a FPS test?

very well explained