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Airguns by Make and Model => Crosman Airguns => Topic started by: RBQChicken on March 06, 2019, 08:17:30 AM

Title: Benjamin 397/2 O-ring sizes
Post by: RBQChicken on March 06, 2019, 08:17:30 AM

If you look at the Crosman schematics for the Benji 397-392 valves, they only have the Crosman part number; They don’t have the universal O-ring size listed.

Can anyone tell me what the universal O-ring numbers are for the following Crosman O-rings:

JTX-080 (front-most valve O-ring)

397-037 (Middle (inside) O-ring)  (I think TimmyMac said this one is size 112)

397-036  (rear-most O-ring)

It’s not that Crosman’s prices and shipping are too high (just the opposite!), but if I could buy them locally I could get on with my project a lot quicker. 

I assume Buna-N 70 durometer is the way to go?

Thanks!

Title: Re: Benjamin 397/2 O-ring sizes
Post by: Psipumper on March 06, 2019, 11:46:53 PM

113 front, 016 rear. Not sure on the middle one.
Just regular buna o-rings.

Title: Re: Benjamin 397/2 O-ring sizes
Post by: RBQChicken on March 07, 2019, 12:02:57 PM

Thanks for the reply.
I read a post by TimmyMac saying the middle (internal) O-ring is a 112, and if you wanted to slightly increase the volume of the valve you could use a taller 113 in that position (not that I'd want to do that for my 397)

Kind of interesting that the front and rear external O-rings are different.  You'd think they'd be the same size.

The sizes (in inches) are:
                                         Cross Section       I.D.         O.D.
#112                                      .103               .487          .693
#113                                      .103               .549          .755
#016                                      .070               .614          .754