Finally got around to fixing my Benjamin 342.

[limbshaker]

So I bought a near mint 1981 Benjamin 342 in the box a few weeks ago. It pumped and fired fine but had a small leak. So after a couple days I decided to reseal it. I got some new parts and started to disassemble the gun. When i was trying to dig out the upper lead seal I slipped up and dropped a punch and it fell into the valve and took a chunk out of the inlet valve seat. DOH!!


That surface must be flat for the flat side of the inlet seal to seal against under pressure. So essentially the gun was ruined. So I put it away for a few days and got a plan together. I had to make a tool that would resurface that little ridge till it was flat again, but it also had to be kept level and true. I dug up a scrap of delrin and a carbon fiber arrow shaft out of my busted arrow bin, and turned down the little delrin scrap to fit snugly inside the valve body. I then pressed the delrin into the arrow shaft so I had a handle. I punched out a circle of 320 grit emory cloth ans glued it to the face of my delrin plug. Here's the tool:


After a few minutes of twisting the tool back and forth, I pulled it out and peeped inside with a flashlight and was delighted to see this:


Success!! So I got my new seals together and started to reassemble the gun. But when i picked up the heavy spring that goes inside the valve, I realized that it was VERY stiff. It was the original spring, but still way stiffer than what I thought it should be. A softer spring here would make the valve easier to knock open and should help clear all the air out with a shot. So against my better judgement I hacked 2 coils off the exhaust end of the spring and closed and finished the ends. The gun went back together fine.

Now here's where it gets interesting... The gun must now be cocked before pumping to let the valve rest on its seat and hold air. I expected this and it's not a problem. When the gun was stock it would only clear 8 pumps before retaining air. Now it will clear at LEAST 15 pumps, with no air retained at all! I'm sure it would clear a couple more pumps, but I'm not going over 15 unless I swap the rubber exhaust seal over to a delrin one.

Here's my velocity numbers:

Beeman Kodiak 21gr: (8 pumps) 545 @ 13.8fpe, (10 pumps) 583 @ 15.8fpe, (14 pumps) 657 @ 20.13fpe!!!

JSB Heavy 18gr: (8 pumps) 585 @ 13.7fpe, (10 pumps) 622 @ 15.5fpe, (14 pumps) 680 @ 18.5fpe

H&N FTT 14.6gr: (8 pumps) 626 @ 12.71fpe, (10 pumps) 673 @ 14.69fpe, (14 pumps) 750 @ 18.2fpe


I have to say, I'm impressed! The gun holds air and functions great, shoots just as hard on 8 pumps as it did stock, but now i have the option to crank it up when I need more grunt. My friend has a stock original '74 Blue Streak and you can hear the hammer bounce with each shot. It shoots 650fps but it's just not "crisp' sounding. This little 342 just lets out a sharp "crack" and even has just a touch of recoil hahaha

I finished the gun off by removing the stock rear sight, and drilling and tapping the breech to fit a Williams peep. Accuracy testing will begin here soon. I have plans to cut off the factory front blade, and replace it with a Weihrauch front globe with the inserts. This will not only make the sighting system a little more precise, but it will also raise the front sight so that the rear peep can use it's full adjustment range and be able to go low enough to zero the gun at close range. That seems to be a common issue when adding a peep to the 342. Hopefully it will work out

[aack73]

good looking gun. good looking numbers too. sounds like you got a winner.

[kelvinator]

Nice save and a nice gun. Love the 342's. I'm very inyerested in the front globe sight install your planning. Please share pictures and post when you get around to it. 

[limbshaker]

So after a lot of filing I got the grooves cut to mount the Weihrauch globe front. I cut the original front sight off, and filed the raised "bump" down flush with the barrel. Then using a sharp pointed 3 sided file, I cut grooves just like the ones on the end of a Weihrauch springer barrel. Then slid the sight right on! Its a much more accurate setup than the original. The rear sight has to be adjusted up to about 3/4 of it's elevation travel to be spot on at 30 yards. I dig it.

[kelvinator]

Nice work indeed. would it be possible to see a close up pic of the front sight showing the mounting detail?