Thinking about a Feinwerkbau 65

Joined: May 27th, 2005, 1:40 am

June 18th, 2018, 6:55 pm #21

Even after a little Googling, I am at a loss as to what  “detent slide buffer” is. But I agree with your hunch, and feel pretty strongly that FWB did not put any parts in the gun that would damage it.

Here is a link I think you will find handy. Note the links to the factory manual and parts diagram at the end:

http://www.pilkguns.com/tenp/spfwb65.htm
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Joined: May 30th, 2018, 3:21 pm

June 18th, 2018, 7:31 pm #22

I have a bit more information now.  The buffer he is talking about is the small one at the bottom in the breech that pushes in the detent slide.  I gather on some FWB 65 the closing of the breech is sufficient to press in the detent slide (without the buffer) and allow the pistol to fire - then the buffer is probably to prevent the metal to metal contact.  He sent me a pic of the breech of his pistol where the breech closure with buffer has been hammering the detent slide in to the point of having a substantial witness mark.  Likely the buffer size could be reduced to the point of just protruding, and that would work optimally.   Assuming that the new materials for the buffer do not deteriorate or deform like the old rubber ones, just a little protrusion will do the job properly. 

This is all based on the pics I have seen - my pistol is now in transit !!

regards -- Roger
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Joined: March 18th, 2011, 6:24 am

June 18th, 2018, 8:17 pm #23

there are three urethane type material, on, in the FWB 65-80-90
the internal buffer and mounts to the front of the piston and there is a metal piston ring on said piston
in the breech area there is a breech seal that is a cone shape that interfaces with the cone shaped breech
and the small barrel that is below the breech seat and it pushes a button inside the breech area
now I have to look and see the purpose of that button, I have never been that curious but that's the layout
go to Feinwerkbau here and look at the diagrams
https://www.feinwerkbau.de/en/Service-D ... d-drawings
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Joined: May 30th, 2018, 3:21 pm

June 18th, 2018, 8:25 pm #24

You would be looking at part   1600-125.3  in the upper left assembly  1600-120.2

the lower of the two urethane parts - smaller little bumper / buffer (or, as FWB says 'dampfer' - sorry, no umlaut capability on my keyboard....)
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Joined: May 27th, 2005, 1:40 am

June 18th, 2018, 9:37 pm #25

When you cock the 65, you will see a small metal tab sticking up near the front bottom of the chamber. This is part of a spring-loaded gizmo that moves backwards to block the trigger mechanism when you cock the pistol—obviously a good idea with a sliding-breech type action. 

The purpose of part 1600.125.3 is to push the tab back forward, thus re-activating the trigger, upon closing the action.

In other words, the gun won’t fire without it.
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Joined: May 30th, 2018, 3:21 pm

June 19th, 2018, 1:55 pm #26

Just got a reply from FWB on the dampfer...   Interesting and provides a tip for correct insertion to avoid malfunction....


"I have contacted our technical distribution department and got some information about the damper 1600.125.3.
 
As you recognized the damper must be built in to prevent metal to metal contact. Without damper 1600.125.3 the “nose” of the dent lever will break off after a while.
The current material of the damper is a bit softer than before but the damper is not produced oversized. You do not have to shave the material.
 
The damper has to be put down to the bottom of the provided hole for perfect function.
Since the hole in the cylinder is closed downwards, it can happen that the tight tolerances of the assembly result in an air cushion and so the damper cannot be pushed to the bottom of the hole.
This leads to a malfunction of the weapon.
Slightly slit the damper in the longitudinal direction with a sharp knife before mounting.
As a result, the air escapes and the damper can be pushed to the bottom of the hole."
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Joined: March 18th, 2011, 6:24 am

June 19th, 2018, 7:32 pm #27

what type of malfunction, could it be the gun shoots and nothing happens, if so I have been there done that on a model 90 rebuild
interesting
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Joined: May 30th, 2018, 3:21 pm

June 19th, 2018, 8:02 pm #28

I guess is that either metal to metal contact, or over driving the detent lever, will damage it over time.  Clearly FWB is aware that the buffer sticking out too far can be a problem.  Likely the over driving of the detent lever is what he is talking about.  The fellow who had the problem said his buffer was protruding about .12 inches beyond the surface.  I doubt that the detent lever contact tab was designed to be pushed in that far - probably bottoming out and then some.  I gather the damper bump should be just proud of the surface.
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Joined: March 18th, 2011, 6:24 am

June 19th, 2018, 8:10 pm #29

if  the bottom buffer if a little to long it would hold open the breech and then the piston would move forward under spring tension when fired and you get a gun that doesn't fire a pellet
I my mind the neither the breech seal or button buffer take any wear at firing but the fact the buffer can hold the breech open is great info to me
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oldcoot
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oldcoot
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Joined: April 29th, 2005, 6:57 pm

June 20th, 2018, 4:16 pm #30

Thanks. That trick of slitting the damper button lengthwise slightly to relieve air pressure is a great nugget of information.
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