yep, mine is the screw type as well, I was having this same problem, What i did was drop a Penny in behind the C02 cylinder, It fits perfectly. Then use an allen wrench to put a little bit of xtra torque on it,
And if you havnt already, you should go to walmart and buy a little bottle of lube in the back with the paintball stuff called "Liquid Fire"
You and i have the SAME Type pistol, and you are having all the same problems i had with mine, If you aren't already, you need to go but that Lube, and put a few drops on the needle that punctures the CO2 almost Every-time you use it, not only will it keep that oring lubed and leak free, But it does wonders for the cupseal and hammer orings, DRASTICALLY improving your Accuracy.
Die Young, Or Live Forever
PT EXTREME PISTOL + ACCESSORIES