I've been searching all over for a good airgun resource and I came across this forum. I've already done a lot of reading
I have a Benjamin 397 that I bought about 15 years ago. It has been modified to shoot under 500 fps (bought it at Canadian Tire). I decided to take it out and do some plinking the other day and I got to thinking..now that I have my PAL, can I put it back to factory specs (800 fps). I've been told this can be done, but that I'll need "parts". Does anyone know what I would need to get, and where to get it from? After about 4 pumps, the gun starts bleeding off presure (it sounds like a bullfrog). I'm not sure what needs to be changed to get it back to it's proper velocity.
If I remember correctly, I did contact D&L a while back. They wanted me to send the rifle to them. While this is an option, I'd like to see if I could get the parts needed and make the changes myself. With the shipping & repair costs, sending my Benji away might not be worth it.
Well, I decided to be brave and disassemble my Benji. With some help from my dad, we were able to find out that the piston in the Canadian model has a spring type pressure release valve in it. After about 30 minutes and a few shims later, she was up to full power. I gave it the old "yellow pages" test and was happy to see that it almost went clean through with 7 pumps.
Thanks for the info, I'll give it a try. Has anyone else attempted this modification? Is there anything I should be aware of, or look out for? Any info is much appreciated.
Well, the hardest part of this job was getting the pins to come out. They were in there pretty tight. After that, it was very straight forward. I just added more washers between the spring and the end cap until the spring was fully compressed. Now the valve can't release any air during pumping. I'm very satisfied with the power increase.
check the centre of the pump cup for a hole if its there then you need to oder in the american pump cup and piston arm rod its one unit basicaly in alot of the benji guns that are detuned for canada .. cups and be replaced but the rod does have something extra to do with it as well from what i have seen ,,plugging bleed holes and all that junk are just not suitable fixes and in a gun like a benji i would not even think of doing it . i would just order in the american parts in and if you ever did decide you wanted to sell it you could detune it again and sell the gun with no hassles cause you atleast made sure it was non pal based when you sold it.. what the new owner does has nothing to do with you if they jack it back up again ...
