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All Springer/NP/PCP Air Gun Discussion General > American/U.S. Air Gun Gates

Refurb of an old 342 Benjamin.

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grandadg:
A friend of mine has had this gun for decades and the last 9/10 years it has been sitting in a cupboard with duff seals. After he bubbered the valve removal he then gave up after seeing the seals were too far gone to even think about him trying a fix.These sea going Engineers are used to much larger sealing problems LOL.So I volunteered to look at it for him.Well first things first as they say it now needed a new valve body as well as a stem and inlet seal. So I turned a new brass valve body on the lathe then made a stem from ptfe and used a slim wafer of the same to form a new inlet seal well I just could not get it to pump up. So I thought beggar it get a set of original seals and be done with it. So I sold my soul for the price of a set of seals (Kerist they are expensive!!!!) And still no luck !! "Now hold on" says I "there must be something else to it than meets the eye". So I pulled it down again using the new tool I had made for the job and carefully looked over everything until the penny dropped I had made the seat of the valve a bit too close to the size of the valve stem swell where it meets the seal You know the trumpet shape that keeps the seal from riding up the stem? I had not allowed for the seal compressing and more of the trumpet end of the stem being seen,or not! as the case may be !!Also when I put the new stem into the valve there was a lot of play in the hole through the and the stem was able to shift slightly. So into the shed to turn valve body number 2 !! this time I used a number drill instead of the 4mm drill I had used the first time  and I also matched the seat dia and hole through for the throat to the oem body too.Success was the result It held air and I was able to pump it and fire it .So riddled with curiosity I looked at the stuff I had re sealed and the first new brass body and thought I wonder if I had used a new piece of rod to make the new stem,no sooner thought than started so I made up another ptfe stem using Stainless steel 4mm rod from the stock pile. and "dang" if that didn't seal as well. Moral of this story is never try and mix metric and imperial sizes in one build.! Any how we now have a gun that fires like new and this morning I have sanded down the stock and fore arm and have stained it slightly Darker Walnut and am about to give it a coating of Alkanet root oil before starting the gun stock oil treatment. This will give the Walnut a beautiful red tinge when finished and make her look the part. I'll put some pics up when all is done,I don't want to tempt fate by showing her off too early, only to have another problem now do I ???
Now can anyone tell me what sort of power I should be looking at over the Chrony with this little beauty ??

Flint:
Wow, sounds like you have done a great job with it.  I'm always so impressed with the guys who can actually build parts from scratch.  Hat's off to you. 

I would say with 8 pumps and 14.3 grain pellets you should expect 575 on the low end and 625 on the high end.

grandadg:
Thanks Billy I'll give her a run over the Chrony I have some Crosman Premier and some Acupel in .22 and I also think I have some JSB lightweights too they are around the 14 grain mark. So we are looking at around 11-12 fpe well that is good it will keep him legal when he gets it back. As you know here in the UK those airgunners who are not Fire Arms Certified have to stick with sub 12fpe.

Habanero69er:
Just out curiosity, I chronied my stock 1985-'86? Racine 342 to see what it was shooting. The lightest pellets I have are 18g JSBs.
Here's the results:

3 pumps
436.6
431.8
438.3   AVG 436.4  7.7fpe
437.5
437.7
4 pumps
489.7
484.2
487.3   AVG 486.5  9.5fpe
486.9
484.6
5 pumps
530.3
525.9
531.3   AVG 527.5  11.2fpe
529.9
520.3
6 pumps
565.5
565.7
566.5   AVG 566.3  12.9fpe
569.3
564.4
7 pumps
591.0
597.1
595.0   AVG 593.0  14.2fpe
590.0
591.7
8 pumps
620.8
625.6
631.8   AVG 625.1  15.7fpe
627.2
620.2
9 pumps
642.8
648.1
647.0   AVG 648.1  16.9fpe
649.3
643.3
10 pumps
662.4
664.5
663.4   AVG 666.1  17.9fpe
668.4
671.9

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