Airgunning

     Weihrauch HW97K stripdown & installation Venom kit     

Disclaimer: if and when you decide to follow these instruction, please be aware that I cannot be held responsible for any physical or mechanical damage that might occur.

- First remove the stock screws.

- remove the screws at the trigger guard, start with the one at the back of the guard.

- next remove the front screw (when reinstalling, tighten the back trigger guard screw at last and don't overtighten).

- remove the action from the stock.

- don't loose the small screw at the back of the trigger block, it's kept in place only by some grease.

- remove the pins which hold the trigger block in the trigger house with a suitable drift.

- when the trigger block comes loose, the safety jumps out as well.  Make sure you don't loose the small safety pin spring.

- after removal of the 2 pins, the trigger block can be taken out of the trigger house.

- unscrew the fixing nut that secures the trigger house.

- pay attention not to lose that tiny ring.

- rather than loosening the rear cocking lever, remove the complete underlever construction. Remove the pin with a drift; the pin can be used again without any problems afterwards.

- remove the underlever carefully, don't put any force on the cocking shoe as it is rather fragile.

- carefully remove the cocking shoe from the compression tube, don't use excessive force.

- the anti-bear trap system is set free as well, don't forget to install it again later on.  If you want to be able to decock the HW97K, don't install the anti-bear trap again, but be carefull when loading the gun if you don't want to lose any fingers.

- time to remove the trigger housing block.  Often it is very tight. Find a metal bar that fits nicely in the sleeve and hit it with a hammer.  Put some rags around the bar to avoid damaging the action.

- after a few taps, the trigger housing block comes loose and it further unscrews quite easily.

- when the trigger housing block is almost completely unscrewed, pay attention as the spring is about to launch the trigger housing block in outer space ;-).  The factory spring has quite some preload and tension. If you don't have much experience or don't feel comfortable about this, a spring compressor might be an excellent idea.

 - the picture below gives you an idea about the spring load in the factory spring.

- next, remove the compression tube from the action.

- and remove the piston from the compression tube.

- there is no need to take the gun further apart.

- strange, there shouldn't be any grease in front of the piston seal ;-).. 

- time for a new and better piston seal.  Unseat the old seal, a flat screwdriver comes in handy.

- put the screwdriver under the seal ...

... and off it goes.

- all parts are degreased carefully and checked for blemishes (burrs etc.) which are corrected if possible.  Polishing some of the parts might be a good idea.  When everything is OK, the gun can be put together again or a Venom tuning kit can be installed. 

- a venom kit is supplied with an insulator which avoids that the cocking shoe makes contact with the spring.  The insulator is installed in the piston.

- the 12 fpe venom spring is much shorter than the factory HW97K-veer, the venom seal is a much better quality one.  The kit is supplied with some washers to fine-tune the power.

- mount the venom seal on the piston.

- looking much better than the factory seal.

- the seal and piston are treated with the appropriate lubricants (less is better) and re-installed in the compression tube. The compression tube is treated with some molygrease and re-installed in the action.

- time to re-install the spring.  For the spring I use maccari heavy tar instead of molygrease.  Don't use too much tar, only a tiny coat on the outside of the spring. 

- rubber gloves are advisable, unless you like black fingers.  Note the front spring guide.

- with the spring completely tarred and some molygrease on the spring guides, everything is ready for re-installation. It is clear there is far less preload on the venom spring.

- the trigger housing block is screwed back on the gun.

- the trigger is fine-tuned.  The contact points are polished.  With the big screw, the weight of pull of the first stage is adjusted.

- the  torx screw in front of the trigger blade adjusts the second stage let-of point, eliminating possible creep on the trigger.  Be carefull no to set it to light as it will make the gun unsafe.

- complete the re-installation and you're ready for the first shot.

November 13, 2004 by Mario Severi