Benjamin 397P Phase 1

[jirushi]

Nice 342!
And a lot of fun to bring back to life.
I still have a brass valve body for you if you want; send me a pm and I am happy to post to you foc.
I've tried to use an inlet seal carrier with "post" in the middle in a gun that had an older type inlet seal carrier without that post.
It didn't work. I think the inlet seal seat is different for both types. But perhaps you will get better results.
Sheridan and Benjamin used both types. They have exactly the same configurations.
I highly recommend Lawrie for resealing the old valve and inlet seal carrier without hole in the middle if you come to the conclusion that that is necessary at some point.
Btw I received hammer springs with power adjusters from Ped recently. Super cool. Will start to experiment with those soon!

[ratbuster2240]

Thank you Louis that is very good of you and likewise if you need anything I can check my spares box.

When Benjamin bought out Sheridan in 1977 they started using the Sheridan valve. Hopefully with my 342 being 1980 a Sheridan inlet will fit. I shall report back either way and If not I'll send Lawrie a message.

That does sound like fun having a dual shot pumper and without power restrictions where you are both shots will produce very good power.

[ratbuster2240]

I put the 342 back together and now waiting to see if it holds air.
I cleaned the stock up woth 0000 fine wire wool and beeswax furniture polish.







All internals were polished ready for new seals.

[jirushi]

Very very nice! Are the new seals in yet?
This is my 347, I really like it, although I think the Sheridan's triggers are a bit better (lighter/less creep?). There is variation between Streaks though.
How is the trigger on your 342?



This is a simple mod I did on my 347. And my Taiyo Juki Bobcat: this is a photo of the Bobcat.
Little piece of leather super glued on the trigger, to reduce sear engagement. With a scalpel blade (easy to get hold of when you're a vet lol), you can adjust the thickness.
A more sophisticated approach would be to have a screw where the leather is, to adjust sears engagement. On which gun did I see this? I forgot lol.
Another important factor is the trigger spring strength. The spring on this photo is too weak, making the gun unsafe: when I cock it, the sear doesn't always grip well.
I have now installed a stronger spring.
Collecting springs of all sizes is something I must start to do. A friend advised me to collect toys, broken umbrella's and anything that can have springs inside.

[ratbuster2240]

I didn't know you were a vet Louis? what a great profession. Do you work with large or small animals?

A friend of mine was a vet sadly he passed away at Xmas.
He was very interesting to talk to and one of the last things we discussed was Brucellosis, he said there's a lot of older moody vets out there that he thinks may have caught it in their careers.

I love the grain on your 347 stock. Does it shoot as good as it looks?

All the seals are in and it's shooting hard going from. 177 - .20 and now .22 I've felt the difference.

I'm looking forward to testing the power and accuracy, I may mount the Weaver pistol scope and Mac1 mount because the .22 barrel has the same diameter as the Sheridans. After getting good results with the peep sight I'll be keeping them on the Sheridan and 397P.

Mine doesn't have the pre-drilled breech for williams peep, I think they started doing that in the mid 80's. Is your 347 made in Racine WI or St Louis MO? I'm sure I read that on the older Benji' if you drill and tap for a peep you'll have to raise the front sight height. I think they later remedied this.

You are right about the triggers, the benjis are heavier, I will have to measure this with my guage. It's crisp enough but not as light as the Sheridan. Somebody had modified my Sheridan trigger sear allowing adjustment. It certainly does the trick but I removed the adjuster screw until I properly bump test it and thread lock it.



Great work on your trigger improvements I never thought about doing that.

[jirushi]

Great that your 342 is working again!
It will be interesting to read about the results (power, accuracy).

My 347 works well, although I must cock it first before pumping; otherwise the air goes straight through the valve. I think I should have a look at the springs in the valve, but as it works when I cock it first, and it is in such untouched condition, I have decided to leave it for now. Max power is about 8 ft/lbs iirc. That's with 8 pumps. The trigger is heavy, but a bit better with the leather sears engagement reducer thingy.
Strangely enough, I was unable to make it work with the Williams peep sight. It keeps shooting a few inches to one side (forgot if it was left or right), even at max adjustment of the peep sight. The barrel is straight. Must look into this. Must also check if it was made in St Louis or Racine.

Moody vets with brucellosis! That could explain lots of things with some of my previous employers lol.
I used to do mixed practice (all creatures great and small), now I treat mostly cats and dogs.

Cheers, Louis

Ps. The wood on these Americans is often really nice indeed

[ratbuster2240]

I've got into the habit of cocking them before pumping, just in case the hammer is resting on the valve.

The Williams peep may have shot too far to the right, I think grinding off a little on the back of the sight will allow the aperture to come over.

[ratbuster2240]

A nice day for plinking and zeroing today, a slight adjustment to the crude sights and it was bang on at 20 yards. The sights are very basic but focusing on the front blade as if using a peep sight seems to be the best way to use them.



It's the first time testing the accuracy and it grouped quite well with cheap pellets, I will try JSBs next time.

One job I did before shooting it was to replace the clunking rectangular lever rivet. So I drilled the keyed side and punched it out.



The spring lever had quite a rough spot where the lever link
has contacted it so everything got smoothed out and cleaned up.



The rivet was very ovalled but the lever holes were still nice and round thanks to the rivet being sacrificial.



I installed a new rivet from Mac1 airguns, it sat a little proud so I filed it down a little once installed.

Unlike the previous owner, I will be keeping it well lubricated. It now pumps up smoothly without sounding like an arthritic Knee joint.

[--ped--]

it's suprising how much the rivet can wear and you were looky that the lik arm hadn't worn

[ratbuster2240]

Ped, I was putting off this job because I was worried about causing more damage but now I've done it I'm confident doing it again.

Apparently having a lot of slop can cause power to be lost. It must change the lever geometry reducing the amount of air going in with each pump.

[--ped--]

it does with a fixed piston as the head space is increased but if you have an adj piston the play can be eliminated but it then inc wear

[ratbuster2240]

That makes sense, the adjustable piston compensates for wear in several areas and not just the rubber pump cup.

it does with a fixed piston as the head space is increased but if you have an adj piston the play can be eliminated but it then inc wear

[jirushi]

Great results and improvements.
Your Benjamin looks great in the sun!
Have you done a shot string?

Cheers, Louis

Ps. I still need to take my 347 out of its slip to check where and when it was made. Will do!

[ratbuster2240]

Thanks Louis I'm very happy with it, it feels like a new gun. I'm hoping for a new shoot through chronograph in May for my birthday. I won't be putting a silencer on this so I can't use my trusty Combro. The 397 had very little deviation in FPS, so I hope this is the same.

I have a feeling your 347 might be pre 1977 before they bought out Sheridan and started using their valves. The wood is very pretty and they got plainer as time went on also you said the Sheridan inlet carrier didn't work in yours.

Great results and improvements.
Your Benjamin looks great in the sun!
Have you done a shot string?

Cheers, Louis

Ps. I still need to take my 347 out of its slip to check where and when it was made. Will do!

[ratbuster2240]

When I first took ownership of these classic multi pumps I thought there was very little upgradeable parts available. Thankfully there's some really talented engineers out there and I've recently received these nice stainless steel parts. The stainless steel bolt is to replace one of mine that has flaking chrome and I have very durable sizes 003 and 004 Urethane to go on my .177 and .20. The Benji 342 doesn't have one, but the metal to metal design seals just fine without any puffs of air at the breech.

Next is an ss Sheridan valve body this will replace the restricted UK version which only produces about 9 fpe. It's shooting very well at this power so I might leave it for now. I have been lucky opening up these guns and finding the valve nuts are in good condition, now I have spare if one has been damaged from using the wrong tools.

The other smaller items are a new sheridan bolt lug and socket and a pin link pin for my 342.



The good thing about the Mac1 scope mount is you can take it off the barrel with the scope still attached to the mount. This is useful for checking the accuracy. It balanced quite nicely on the little 342 but for short range at 10-20 yards I'll be sticking with the open sights. Even the Mac1 mount which is considered to be one of the better designs just doesn't feel as good as peep sights on these.



Both the C-series and and 397 now have Williams peep sights on. The latest one I got the screws didn't touch the bolt so they didn't need shortening.