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Swapping the Walther LGU's trigger

12/12/2014

8 Comments

 
BEFORE ANYTHING ELSE, I am required to post this, the legal disclaimers:


1.- Swapping the trigger blades WILL invalidate the warranty of your rifle.
2.- ANY user intervention in the triggers MAY result in an UNSAFE condition. Once you get into the trigger you are on your own.
3.- I have no control of YOUR actions, so I can take NO responsibility for the results YOU get. This process proved safe and sound in MY gun. I cannot guarantee that it will be the same in YOURS.

Having said that to the satisfaction of the company's counsel, lets start:

Following our initial experiments with the Walter LGU and its excellent performance, but horrible trigger; we decided to distribute the "Match Abzug" (or "Tuning Trigger") to all those that got their guns from Ct Custom Airguns free of charge. We saw no reason to have an excellent gun saddled by a hideous trigger . . . or so we thought! LOL! but more on that later.

The "Tuning Triggers" were obtained and mailed to all, but time precluded the real effort of creating a detailed swap-guide for people that are not experienced tuners till yesterday, when we could afford the time and tranquility needed to tackle the operation with the mind set of a beginner. Those of you that are experienced airgun tinkerers will have to bear with me and if I go too fast, then those that have questions, do feel free to post them as comments to this entry.

SO, here we go.
Picture
Take all accessories off the gun: scope, slings, sights, anything that is extraneous must come off.
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Undo FIRST the two FRONT screws and then undo the rear TWO screws. NOTE well how tight each screw is. NOTE that the front screws have TWO washers each: a star washer near to the screw's head and a FLAT washer next to the stock. Reversing this order will destroy the stock's fine screw hole finish, expose your stock to humidity entry and create a mess. Do NOT reverse the order of the washers! Since the action cannot be completely bedded to the stock in an airgun, the tightness of the screws plays an important role in the accuracy of the rifle.
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If you cannot remove the trigger guard, don't worry, remove the stock with the trigger guard and then remove the guard from the stock. Do NOT loose any of the screws! Though they are common screws, they are metric and not easily replaced in the typical US general store.
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Note how the action is held closed by two pins. Note their relative size and position. Since the two pins are different, there is no chance of putting the wrong pìn in a hole, but DO pay attention to the SENSE the pins go into the action. In European habits and customs, pins usually go INTO the action from right to left (the right and left sides are ALWAYS referred to with the gun pointing AWAY from the gunsmith). Because most pins in well made guns will have a slightly better chamfer on their LEFT (so that they can go into gun from the right), take the pins out by using a punch ALSO from the RIGHT. These are cylindrical pins, so they should be taken out in the same sense they went in.
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Now, to set the gun into a spring compressor, make sure you protect the trigger block casting and the muzzle by using pads and wooden blocks to apply the pressure.
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I would be standing to the right of this picture, BEHIND the action and spring compressor, holding the light hammer on my right hand and driving the pins from RIGHT TO LEFT. Don't loose the pins.
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Once the pins are out, holding the action down with your left hand use your right hand to unscrew the spring compressor. Easy does it, no one is in a hurry.
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When the spring has decompressed all its pre-compression, you can recuperate the wooden block and allow the action to be pulled apart.
Picture
In the Walther, the guide (the white plastic tube that holds the spring and the piston's stem in place) is attached to the trigger block. This is one of the reasons why there is little spring bounce in this gun. Also note the steel "thrust washer" at the base of the guide abutting with the trigger block. This washer allows the rotation of the spring. All springs rotate when compressing and decompressing.
Picture
For the trigger swap operation you do not HAVE to take out the piston and the spring, but most probably you will want to take them out, just because curiosity is what it is. Here you can see the trigger block (top to bottom), then the spring, and then the piston. The black thingy at the rear of the piston's stem is the "Top Hat" a device that acts like a spacer and also centers the spring in the piston's body. IF you had purchased a replacement spring (springs are "consumables" in most spring-piston airguns), or an aftermarket spring (like Maccari's) you would swap the springs at this point.
Picture
If you wanted to clean the compression cylinder, or replace the breech seal (also a consumable item in most airguns), you would have to extract the compression cylinder (here flanked by the spring and the piston). The rings in the compression cylinder are NOT seals. They are bearing rings and they are split diagonally. In this photo, you can see the front bearing ring in the piston (the white one) as well as the rear bearing ring in the piston's skirt (also white). The green front end of the piston is the piston seal and although not strictly a parachute seal, it does have a buffer ring. This is another reason for the perceived smoothness of the gun. The piston seal is made of a relatively hard elastomer, but it definitely does NOT act as a bearing. NOTE: some people call the linear bearings shown here: "buttons", out of the old habit of placing round buttons at the piston's skirts. But these are NOT buttons, nor should the piston be termed a "buttoned" piston. It is a piston with linear bearings.
Picture
Now remove and store the thrust washer.
Picture
And now let's get to the trigger itself.
Picture
The trigger block is a cast housing that is held together with two screws. Screws will need a flat head screwdriver. Make sure that the blade FITS PERFECTLY the screw. If you have to polish or change the blade, then do so. NOTHING detracts more from the value of a gun than having burred screw slots. It tells anyone looking at the gun that an amateur got in there and raises the doubt about what else could have been changed (if not spoiled) by the person in question.
Picture
The casting is well made and even with loose screws it will not come apart easily. It has to be pried open VERY carefully, the screw the driver's blade is pointing to will always fall, so be careful. This is the screw that regulates the trigger OVERALL RELEASE WEIGHT. Note how the plastic guide also holds a steel bushing in place that will hold the piston's stem when the stem is engaged by the trigger hook.
Picture
This is the trigger in the fired position and with the guide removed.
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This would be the trigger in the cocked position with the guide removed.
Picture
Now, borrow a crochet hook from your wife's and very carefully remove the return spring from the trigger blade's front stub.
Picture
With the return spring's tension removed, the trigger blade is free to come out.
Picture
Side by side comparison of the trigger blades: On the left, the OEM "non-adjustable" plastic trigger blade. On the right, the "Match Abzug". You can clearly see that the plastic blade has one screw, the Match blade has two.
Picture
Even with the bad, out of focus picture you can see that the plastic blade is wider than the metal one. In normal, European usage, the finer the trigger can be adjusted the thinner it will be. Wide trigger shoes and very light trigger weights make UNSAFE guns. Specially in cold weather. So, BE CAREFUL!
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Some writers have claimed that the engaging surfaces of this trigger unit have been polished, this is NOT so. They have a good finish, but they have not been polished. In this picture you can see the point of contact of the FRONT screw of the plastic trigger blade.
Picture
A little bit of jeweler's rouge in a felt drum and the surface becomes so polished that the autofocus of the camera has difficulty focusing into it.
Picture
If you are going to polish the lever surface shown above, then also take the time to polish the screw's tips.
Picture
Now, insert the Match blade into its place and restore the return spring. NOTE that the nuts that are tightened by the stock screws are loosely held in a cavity in the casting. While this is good because non-ferrous casting should never be allowed to be threaded (unless they are high strength aluminum), it also poses the problem that the nuts may turn out of position and then the casting may not close as well as it should. Make sure that all parts are in their proper place: Nuts, safety's detente, safety, trigger wieight spring, guide and bushing. When EVERYTHING is in its rightful place the casting can be closed by hand and the edges will align perfectly. If ANY edge does not close completely, you have something out of place.
Picture
Everything in place and ready to close. You CAN test the trigger once it is closed by pushing the piston into the closed trigger block and allowing it to be taken out of safety and the trigger blade pulled to release the piston. The piston should release completely. Making sure everything works without the mainspring tension is a good idea! Do NOT overlook this test!
Do NOT overtighten the two screws that hold the cast housing together. It would be easy to strip those threads and then you are in big trouble.
Tighten to something between snug and slightly tight and use thread locker, the blue one that is "medium strength" to make sure that the whole housing will not vibrate loose, open, and dropping trigger parts all over the field.

From here, just follow the reverse procedure to put your gun together.

Make sure that you insert the piston into the compression chamber BEFORE you insert the compression chamber into the gun.
Make sure that the Top Hat and Thrust washer are inserted into the spring and guide respectively.
Make sure that you release the anti-beartrap safety when re-inserting the compression chamber.
Make sure you align the compression chamber to the slot in the action for the cocking lug. NOTE that the cocking lug is held onto the compression chamber by a claw that has no hook. It is held in place by the location of a plastic runner that rides on a slot in the stock. The stock is, therefore, a MECHANICAL component of this gun.

Once you have everything together, cock the gun and holding the cocking lever firmly, make sure the trigger fires. Re-cock and fire several times. Once you are satisfied that the trigger unit is working well, then de-cock the gun and head for a test range.

You will need to fire the gun at least 50 times before attempting to reach the final adjustment of the trigger screws. If you polished the lever surface and the trigger screws discussed above, then you can start adjusting, but if not, do not worry, surfaces will become "burnished" by each other and you probably need the trigger time anyway.

Once you have fired the gun at least 50 times, you will need to start screwing IN both screws: first the front and then the rear.
Screw them in by ¼ turns, you will see how the trigger release becomes lighter and crisper. Lighter and crisper.
Adjust till you have the letoff you want.

The adjusting was tougher than the swapping, but once done, you're good for a substantial number of shots. You will have to adjust the fine details after every 1,000 and then after every 5,000 shots, or thereabouts.

HTH

Un abrazo!




Héctor Medina



PS.- in the next blog entry we will tackle what can be done to the PLASTIC trigger blade to make it a good trigger blade.
8 Comments
Willie
8/22/2015 04:22:45

Great report! The screw tip that should be polished, it that one of the two adjustment screws in the new trigger blade? I assume that you polish both sear engagement points? Does the stock help keep the trigger housing unit together?
Thanks again for the very informative explanation!

Reply
HECTOR J MEDINA GOMEZ
8/28/2015 02:53:03

Hello Willie!

You can polish either the single screw in the plastic trigger blade (though you would be better off replacing that screw from the start), and/or you can round and polish the screws that come with the "Match Abzug". Both operations are worthwhile. You should also polish the flat sections of the sears where the screws bear.
I would NOT recommending the engaging surfaces of the sears because it is easy to change the angle and also easy to remove all the case hardening those parts are made of with seriously detrimental consequences.
The trigger housing is held together by two slot headed screws. Do take good care of them as the housing is aluminum and therefore easily stripped.

Thank YOU for reading!


HM

Reply
Brian Breakstone
5/13/2016 18:52:17

Aloha Hector, I discovered your website while trying to get info on my LGU tigger. When the Walter LGU was Introduced to the US I bought one didn't like the plastic one and Immediately purchased the Optional Target trigger which is now hard to obtain. Along with the LGU, I own a HW97 and a TX200. while I do own PCP's I ready enjoy under lever springers. To me they are more challenging because you have to Reset up each shot which I believe make you a better marksman.
I noticed that you are shooting a Diana side lever which interests me. Interested in purchasing An Air King54 in 22cal. The 56TH seemed to heavy to me. Noticed that Diana also makes and under lever as well. The reviews don't seen as positive for that guns quality. Wondering what you think on this subject.
I'm over here on the Big Island of Hawaii, and would Appreciate your help. Thanks.

Mahalo, Brian

Reply
HECTOR J MEDINA GOMEZ
5/14/2016 00:40:28

Hello Brian,

Yes, I shoot a CCA WFTF D54. It is a short stroked gun that yields 12 ft-lbs. I've placed well in some FT matches.

A full power D-54 in 0.22" caliber can be a great gun, but to be FT accurate it needs a lot of work.

Performing all 15 operations required takes about 10 solid hours labour and the addition/exchange of 5 key elements.

Once done, the guns will easily put 5 shots into 1/2' at 35 yards with 20 to 22 ft-lbs of muzzle energy.

A fully tuned gun would cost $1,350 and current delivery times hover at around 4-6 weeks, this includes the right scope mount and the gun will be regulated to a scope you provide (we provide the gun itself).

If you are still interested, contact us using the contact page in this website.

Thanks for considering CT Custom Airguns!


HM

Reply
Sang Lee
7/14/2016 18:55:38

Hello Hector,

An excellent post! Since the Metal Tuning Trigger was discontinued by Walther, I'm getting ready to install Rowan Engineering's Adjustable Trigger so the information you presented is going to help. I have a question however, in the removal of the two pins holding the trigger block in the action.

Below photo 4, you stated that "pins usually go INTO the action from right to left (the right and left sides are ALWAYS referred to with the gun pointing AWAY from the gunsmith)."

Below photo 6, you stated that "I would be standing to the right of this picture, BEHIND the action and spring compressor, holding the light hammer on my right hand and driving the pins from RIGHT TO LEFT." But since the action is now UPSIDE DOWN in your spring compressor, shouldn't you be pushing the pins out from LEFT TO RIGHT as pictured?

I'll be installing the new trigger as soon as it's delivered, hopefully by 07/20/16 or thereabouts so I wanted to request clarification.

Thank you,
Sang Lee

Reply
Hector Medina
7/21/2016 09:09:56

Dear Sang Lee;

Sorry I was not completely clear with the description.
Since the caption is under the photo that shows the gun ALREADY in what you call an "upside down" state I thought it was obvious.
In industry practice, what you call "upside down" is really the "work position" of the gun.
So, NO, you do not need to invert the instructions, with the gun in the "working position" insert the pins from the right, and also remove them from the right.

Hope this helps and apologies for the confusion, the delay in responding obeyed the fact that I was in Canada, shooting their National FT Matches.

Thanks for reading!






Héctor

Reply
CS link
9/18/2016 13:57:26

Swapping the Walther LGU Trigger is a fantastic piece of work - Congratulations! - great information; great photos! When I received my new rifle, one of the two pins holding the rear assembly was missing - strange! Then, I tried and tried cocking it - no, it would not 'fully cock.' I tried adjusting the noisy trigger and found that the trigger adjustment screws actually allowed me to "fine-tune" the cocking mechanism! Now, I have a great air rifle with a "4 pound pull."

Can I make this trigger work? Do I need to buy the European, double metal "adjusting" trigger?" I need your help. Many Thanks,

CS

Reply
HECTOR J MEDINA
9/19/2016 10:54:49

CS,

One question: Did you buy your gun as a refurb or a second hand gun? Missing one of the action closing pins does not seem too "kosher".

To answer your questions:
No you do not need the "Match Abzug".

Read the second part of the LGU tunes:

http://www.ctcustomairguns.com/hectors-airgun-blog/a-yankee-tune-for-the-walther-lgu

And then you can also read the Third part (not trigger related, but powerplant related):

http://www.ctcustomairguns.com/hectors-airgun-blog/a-yankee-tune-for-the-walther-lgu-second-version

Hope this helps.





Héctor

Reply



Leave a Reply.

    Hector Medina

    2012 US National WFTF Spring Piston Champion
    2012 WFTF Spring Piston Grand Prix Winner
    2013 World's WFTF Spring Piston 7th place
    2014 Texas State WFTF Piston Champion
    2014 World's WFTF Spring Piston 5th place.
    2015 Maine State Champion WFTF Piston
    2015 Massachusetts State Champion WFTF Piston
    2015 New York State Champion WFTF Piston
    2015 US National WFTF Piston 2nd Place
    2016 Canadian WFTF Piston Champion
    2016 Pyramyd Air Cup WFTF Piston 1st Place
    2017 US Nationals Open Piston 3rd Place
    2018 WFTC's Member of Team USA Champion Springers
    2018 WFTC's 4th place Veteran Springer
    2020 Puerto Rico GP Piston First Place
    2020 NC State Championships 1st Place Piston
    2022 Maryland State Champion WFTF 
    2022 WFTC's Italy Member of TEAM USA 2nd place Springers
    2022 WFTC's Italy
    2nd Place Veteran Springers

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