Tuning Benjamin 392PA

[Hold_Over]

Freshly resealed 392PA. Tried 4 different types of pellets through it today. The good news, it seems to prefer the classic CPHP commonly available, and cheap as dirt. The bad news... I did not replace the pump cup, so with just new seals, and a shim on the guide for the hammer spring to add a little tension my numbers are a little lower than expected. Average of 565 @ 8 pumps, but incredibly consistent showing only about 3fps deviation between shots. Think I will shoot it this way for a while since that is good enough for what I am doing with it at the moment. I also don't have a pump cup which is why it wasn't changed when I had it apart. I also polished up the trigger contact points, and changed the spring for a lighter pull weight while I was in there, a major improvement to the previous stock feel imo. All in all it is a great gun that I expect to get many hours of shooting time in with.. I have plans to fit a recoil pad to the stock since I want the xtra grip it provides, and the LOP is a bit short for me. 

 

[biohazardman]

Got to love the Benjamin and Crosman pumpers they last for so many decades and you can still get parts to rebuild them. Actually pretty accurate they are also.

I gave my Crosman 342 to my daughter, twenty years back, but still have my Sheridan Blue Streak form the late eighties. It still shoots great too.

I'm always glad to see them rescued and put back into action good job.

 

[Hold_Over]

Got to love the Benjamin and Crosman pumpers they last for so many decades and you can still get parts to rebuild them. Actually pretty accurate they are also.

I gave my Crosman 342 to my daughter, twenty years back, but still have my Sheridan Blue Streak form the late eighties. It still shoots great too.

I'm always glad to see them rescued and put back into action good job.

There is definitely something about the look and feel of these classic rifles. I also have most of a blue streak, mine is a 64 though. Missing some pins for pivot points on the pump arm, the piston assembly [which should be here tomorrow], and needs to be resealed. Something fun to pick away at in my "spare time"...

 

[Hold_Over]

Ordered the new pump cup last night...will be curious to see if that makes all the difference when it comes in.

 

[Hold_Over]

Over the last couple days I set out to add a recoil pad for grip and added LOP. Ordered a Tourbon small, grind to fit style pad....turned out to be way too big to fit without grinding into the vents on the side. Decided to make a base plate and extensions. The base is Purple heart, which adds a little flare to the color scheme at the moment, but will eventually oxidize and turn brown being a much better match to the original wood. Hardware is blackened brass, and bronze. Overall I am very pleased with how it turned out, and definitely like the feel of how it sits into the shoulder better for me.

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[Hold_Over]

New pump cup arrived today, and got it installed. Using the old cup with new seals it was shooting on average 565 fps with cphp ammo. Adding the new cup has bumped that up to a much better 618 fps with the same ammo....Worth IT!!!

 

[.20calguy]

I just did my first rebuild of a 397PA, with the non-soldered valve. I was not expecting to see an aluminum housing in a brass tube. What in the heck were they thinkikng?
I had already ordered the rebuild kit so I had to clean and polish that aluminum, cake filled, valve body back to life. I lubed it with silicone. I thought about putting some "no-alox", that we used in the electrical business, to prevent oxidation between copper and aluminum wire on it, but I just figured I would shoot it a while, and put a brass valve in it later.
Now I'm having some accuracy issues with mine as well.

 

[ray1377]

I really do enjoy shooting my 392. Its bone stock except for a BE1 dovetail scope mount. And I rarely pump past 6 pumps. And it averages 590 to 600 fps using 14.3 grain CPHP's. A bit on the loud side and yes I do know they make LDC mounts for them but I don't want to mess up those classic lines. Only real issue I ever had with it was the first couple times I removed the valve it was a bear. Found out the pump tube was compressed in where they stamped the serial number on the side. After lubing the valve and putting it back in and taking it back out a few times seemed to loosen it up some. I also learned a good trick when getting the valve out. We've always been told to remove all the screws and use the pump arm to squirt the valve out the back. Well it will work a lot better if you will pre-charge the valve with 8 or 10 pumps first. Reason being, if you don't, when you try to use the pump arm to compress the valve out the back the air from the compression goes into the valve like it was designed to do. If the valve is pre-charged it is a lot harder for the air to go in and it uses that air to move the valve rearward and out the tube.
Thx
Ray