Too much vibration when pumping Benjamin 397  

 

EricinMaine
(@ericinmaine)
Joined:5 months  ago
Posts: 38
March 11, 2018 20:39  

After about 20 shots at 8 pumps each,I feel traumatized from the vibration of the pump lever hitting the wood and metal each time I complete a pump cycle.I see that there are 2 pins holding the wood lever on.How can I remove them?Can the wood be moved forward?What can I do to reduce the vibration?

EricinMaine-


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Doug Wall
(@doug-wall)
Joined:5 months  ago
Posts: 40
March 11, 2018 20:55  

I think that you might be stuck. Don't move the wood forward, it lowers the mechanical advantage, and makes it harder to pump. The only possible thing that I can think of would be to mount foam rubber (like wetsuit material) on the outside of the lever and where you are holding the gun when you pump.


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Bob in WV
(@bob-in-wv)
Joined:5 months  ago
Posts: 36
March 11, 2018 22:42  

I have glued a piece of felt on the pump arm where it hits the metal.  It helps a lot and is cheap.

 

Bob in WV


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DaBick
(@dabick)
Joined:4 months  ago
Posts: 14
March 11, 2018 22:56  

Pick up a roll of moleskin at Target.

Its like felt and sticks real well!

drew


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Steve in NC
(@steve-in-nc)
Dealer
Joined:5 months  ago
Posts: 194
March 11, 2018 23:37  

The Benji forearm pins are the hollow spring type.  

So you can fit a 1/16" bit into them and drill through to the other side of the wood, then use the resulting holes to guide a 1/8" bit to the pin, creating through holes you can then use to tap the pins out, releasing the forearm.  But given your underlying concern, this is mostly academic because, as has been said, moving the forearm really wouldn't help.

Besides the suggestions for padding, another trick is to install a nylon screw (e.g., #10-32) into the inside of the forearm near the free end, and adjust it so prevents the wood from contacting the pump tube and acts as a spacer to stop pump arm motion just past the "cam-over" point.

392spacer

Besides reducing the shock and noise of closing, this also makes the arm much easier to open at the beginning of each stroke, thus reducing pumping effort.

Edited: 3 months  ago

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EricinMaine
(@ericinmaine)
Joined:5 months  ago
Posts: 38
March 12, 2018 21:56  

Doug,your idea makes me wonder if tte right size pipe insulation would slip on the pump lever and stay with some 2- way tape.Also,I just thought of bicycling gloves.They have padded palms ,and the finger parts stop below the 1st knuckle.That would allow me to work the bolt and load pellets while wearing them.I'm going to try putting foam between the wood and the metal first, and hope that will do it.Thank You .

EricinMaine-


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Sebring Plus
(@sebring-plus)
Joined:3 months  ago
Posts: 3
March 12, 2018 22:27  

A short piece of fuel line tubing shoved in the slot in the arm works ok.


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EricinMaine
(@ericinmaine)
Joined:5 months  ago
Posts: 38
March 12, 2018 23:27  

Bob,Drew,Sebring plus,Steve in NC...

Bob,Drew,and Sebring plus-Thank You ,my version of your suggestions was to use what I had on hand ,for now.I have some FROST KING camper mounting tape.It is used between truck caps and the pickup sides around the bed,to provide a seal.It has a sticky side.It is working well for now.When it falls off ,I think I'll try Steve's more permanent solution.

Steve in NC--for a 10-32 steel screw, a #21 drill bit is recommended for the hole to be tapped (probable 68 to 76 % thread).I would probably crack the wood if I tried to tap that hole ,and it likely wouldn't work anyway.So do you think a #22 bit would allow the nylon threads to squash in there and still give it enough purchase to hold?Sorry;you have to tell some of us EVERYTHING.(er-but you don't have to tell me how to hold my mouth while I'm doin' the drillin').

EricinMaine-


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Steve in NC
(@steve-in-nc)
Dealer
Joined:5 months  ago
Posts: 194
March 13, 2018 00:49  

I'd go bigger if you want the screw to self-tap:  #18 or 19.


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DanWesson
(@danwesson)
Joined:5 months  ago
Posts: 13
March 13, 2018 06:47  

As Bob mentioned earlier, felt works good. I've had luck with furniture pads which have adhesive on one side. I use the little, tiny foam discs and adhere two of them inside the pumping arm. This greatly reduces the "clap" of the wood against the metal.

The plastic hand guards made for Benjamin and Sheridan rifles (and pistols) is the key. Originals come up for sale every now and then, but there's a couple of guys who sell quality reproductions of these hand guards which work (and look) just fine. I use them on every Benjamin and Sheridan I own. 

 

Here's an example, but there's other places on the internet you can find these hand guards: 

https://www.worthpoint.com/worthopedia/hand-grd-benjamin-sheridan-air-rifle-135462783

 

 

 


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Airguntunes
(@scottblair)
Member of Trade
Joined:5 months  ago
Posts: 33
March 13, 2018 15:41  
Posted by: DanWesson

As Bob mentioned earlier, felt works good. I've had luck with furniture pads which have adhesive on one side. I use the little, tiny foam discs and adhere two of them inside the pumping arm. This greatly reduces the "clap" of the wood against the metal.

The plastic hand guards made for Benjamin and Sheridan rifles (and pistols) is the key. Originals come up for sale every now and then, but there's a couple of guys who sell quality reproductions of these hand guards which work (and look) just fine. I use them on every Benjamin and Sheridan I own. 

 

Here's an example, but there's other places on the internet you can find these hand guards: 

https://www.worthpoint.com/worthopedia/hand-grd-benjamin-sheridan-air-rifle-135462783

 

 

 

The hand guards are available from a gentleman in Texas. Keith Urquhart. $10 each plus shipping. His email is

quietman972@yahoo.com

They are exact replicas of the original. Perfect fit.

Edited: 3 months  ago

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EricinMaine
(@ericinmaine)
Joined:5 months  ago
Posts: 38
March 14, 2018 19:07  

Steve in  NC,Thank You for the idea,and the walk-thu.

EricinMaine-


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