I love it when a plan comes together: L-G-U trigger tune

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JohnnyPiston

JohnnyPiston

Member
Nov 18, 2017
714
39
NC, United States
Actually, my expectations have been completely surpassed!

I posted this on the FB Walther LGU group and on my FT Springers page, but let me share here:

I finally set aside some time to work on my LGU trigger. 5 hours invested, enjoyed every minute. Painstaking, meticulous, all by hand. Stoning, polishing, maintaining all original sear geometry. Reassembled, now with Rowan blade instead of metal tuning trigger, adjusted, and ready for more shooting tomorrow. Feels very nice, significant improvement. Safety button function maintained: I can make it excellent and break at a few ounces without but I want to have the safety working.

This Rowan blade has 3 sear holes and I used the forward most holes.

 In the past I've had one of Bruno's fully adjustable competition blades installed in an unstoned unit and without the safety linkages and a softer tension pull spring that trigger was what I'd call nice and breaking at around 3 ounces. 

Currently I have another LGU without safety linkages and a Rowan blade, it's also nice and breaking very light. Unstoned unit.

For this new LGU I wanted to maintain the safety function, have a trigger that would positively return to position if pressure was let off from 2nd stage wall, and break crisply at around 6-8 ounces. 

It wasn't an "in and out" 1 hour stoning job- it took me 5 hours but I methodocally addressed EVERY critical linkage and contact point inside that funky trigger unit😉. Additionally, I learned that the positioning of the 1st stage travel take up (not 1st sear adjustment screw), if screwed in too much adversely affects the functioning of the bottom sliding safety linkage. 1/16th of a turn out, etc etc and I finally got the position right. Original tension pull adjustment spring- uncut. I did remove the spring that connects the trigger to the top sear. 

Trigger has plenty of sear engagement, was tested with several knocks without mainspring tension out of the action and when assembled with a rubber mallet on buttstock and fist pounded against side of action/stock- no accidental discharge.

1st stage take up is as smooth as any refined Rekord/TX200, and the glass toothpick breaks at what I estimate to be 5-6 ounces. But more importantly: SAFETY FUNCTION is maintained. 

If I can recreate this same trigger set up in my other LGU with Rowan blade, I will consider reinstalling the safety linkages. 

Now to shoot 1 or 3 thousand pellets and see how it all holds up. 😉

I have actually since further refined the sear adjustments as well as the tension pull weight screw (tension pull weight spring is UNCUT, non modified). It is now breaking MUCH lighter than the previously estimated 5-6 ounces.😉

Here's a video showing the trigger in action, bringing the blade back to the 2nd stage wall quickly and repeatedly for 20 times, me talking about the work done, performing a safety test to ensure a high level of sear engagement and prevent accidental discharge, a short glimpse into how I like to test my match triggers, and a few more trigger pulls: https://youtu.be/CUZFnquGBwo

It was an immensely satisfying project and I hope to recreate the same results in my other LGU Master Pro. 

L-G-U, loving it!

Thanks for looking!

Jonathan
 
Very cool. I have a Walter parrus and the only thing I don't like is the trigger. Perhaps a metal aftermarket trigger will present itself and I can do some polishing. What kind of stones do you use? I've been looking for some. Right now I use a knife sharpener Arkansas stone but I need some thinner options. Spyderco makes some but I really don't know what's the best kind. Thanks buddy great review of your technique! 
 
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Nicely done! I just wanted to say I can relate to both the multi-hour effort and the corresponding sense that it was totally worth it. Every time you pick it up from now on, you'll appreciate the smoothness and effortlessness with which the blade moves, followed by a crisp snap, and be immediately reminded why the effort was worth it. Then again and again, many thousands of times over. Never will the thought intrude that says, "You know, I could have done without that.". Instead it will the one that says, "I only wish I had done this sooner!".
 
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Raden, for most smoothing work done to flat surfaces, I like using wet/dry paper against a piece of glass or granite. 400 grit up through 2000 grit generally, and finally a mirror polish using a buffing wheel. However when dealing with extraordinarily hard materials (hardened steel or sintered metal), I start with a diamond hone to develop a level surface and then move over to the wet/dry paper. In either case, there's never a concern with wear (dishing) like it is with a stone.

For convex surfaces (outside of curves), I simultaneously drag and roll the part against the sandpaper or the diamond hone.

For concave surfaces (inside of curves), I use a rubberized polishing bit (Cratex being the familiar brand name but generic ones work great). I keep a few sizes on hand, 4mm up to 10mm, and I use the largest one I can that doesn't exceed the curvature of the part I'm smoothing. In doing so, it maintains a larger contact patch so as to both prevent dishing and complete the work sooner. Get the polishing bit spinning in a drill press or handheld drill and bring the workpiece into contact with it. By wetting the polishing bit with a little oil, it becomes easy to see when the workpiece is uniformly contacting the surface because it creates a dry-looking ring on the bit as it spins.

 
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Very cool. I have a Walter parrus and the only thing I don't like is the trigger. Perhaps a metal aftermarket trigger will present itself and I can do some polishing. What kind of stones do you use? I've been looking for some. Right now I use a knife sharpener Arkansas stone but I need some thinner options. Spyderco makes some but I really don't know what's the best kind. Thanks buddy great review of your technique!
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Cheers Raden1942, thank you buddy. 


I use Spyderco stones now (very good quality in my opinion) but am looking to “taking the plunge” and try some Arkansas and India stones as well. It’s not against the law you know🤓. LOTS of hand polishing as well. More like finger polishing. Right index finger better get used to it. LOL 

If you ever get inside, shoot me a couple pics of your Parrus trigger unit (not sure if it’s the same as the LGU/LGV unit?), I’d like to eyeball it and have an idea of how it works. 



 
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Nicely done! I just wanted to say I can relate to both the multi-hour effort and the corresponding sense that it was totally worth it. Every time you pick it up from now on, you'll appreciate the smoothness and effortlessness with which the blade moves, followed by a crisp snap, and be immediately reminded why the effort was worth it. Then again and again, many thousands of times over. Never will the thought intrude that says, "You know, I could have done without that.". Instead it will the one that says, "I only wish I had done this sooner!".
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nervoustrig (COOL name!), cheers pal, yes you absolutely nailed it. Learned so much on this first LGU trigger unit, and will apply it again. And again🤓😉👍
 
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Very nice. And I applaud your effort to do it all “by the books” so to speak. You now have a perfectly functioning and custom trigger without any compromise.
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270winddude many thanks buddy. I’ve said it before, these guns are scary accurate even with the heavy plastic, less than ideal trigger. The nice trigger just makes the whole shooting experience so much more enjoyable and pleasant. 👍
 
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JohnnyPiston,

Thanks for sharing. You inspired me to adjust my original 2-screw Rowan trigger. I have the safety working again. Instead of a 2 stage setting, I have the trigger set at a one pound one stage with a very short travel. I wanted to replicate the trigger on a Winchester model 52 rimfire match rifle - heavy crisp but zero travel.

Regards,

Leo
 
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You’re just having too much fun! 

I can sympathize, once I figured out how to refine a QB trigger group, it becomes so nice that I can no longer stand to use one in factory form.
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Too much fun? Guilty as charged! Learning, troubleshooting, executing and obtaining desired results is FUN. 

Yesterday I took out the LGU with my first tuned trigger unit and from dime sized targets at 17 yards to plastic golf ball sized targets at 32 yards in stiff breezes I could not miss: shooting offhand with magnification set at 8x. Fun, fun times.

Last night I completed my 2nd LGU tune on my "OG" LGU, and despite being very nice before (no working safety function, safety linkages REMOVED, Rowan blade fitted) and breaking at a few ounces, WITH everything NOW addressed (TLC given to the safety linkages and clamshell chassis in addition to stoning/polishing/eliminating friction of all contacting surfaces) it is actually BETTER with the safety function intact. Plenty of sear engagement, smooth take up, ultra distinct 2nd stage wall, absolutely zero creep and a crisp break that made my eyes water. Has a refined feel that it did not have before.

Onwards & upwards, SAFETY FIRST! 
 
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JohnnyPiston,

Thanks for sharing. You inspired me to adjust my original 2-screw Rowan trigger. I have the safety working again. Instead of a 2 stage setting, I have the trigger set at a one pound one stage with a very short travel. I wanted to replicate the trigger on a Winchester model 52 rimfire match rifle - heavy crisp but zero travel.

Regards,

Leo
Click to expand...

Cheers Leo, 

So you have the “vintage” Rowan trigger🤓👍

I’ve used the OEM plastic trigger, the OEM Match Azbug (aluminium trigger with 2 seat adjustment screws with the same spacing as your Rowan blade), BMS Precision adjustable match trigger blade (for competition shooting) and the Rowan blade with 3 sear screw positions. 


While the BMS & Rowan 3 screw blade CAN offer feather light pulls without the safety and especially with a cut/shortened/replaced tension pull spring (even in a unit that hasn’t been stoned/polished), the blade will not repeatedly return when pressure is relieved from the 2nd stage breaking point (unsafe, more susceptible to accidental/premature/unintended discharge ) and the crispy break factor is low. And I really like the crispy break factor🤓.

Wish you could shoot one of my LGU’s to test out the trigger function, but you may not want to put it down 😉.


 
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I have posted my trigger mod a few times so I will not get into that area again, but it does involve much of the same things Johnny Piston did.

Too bad I didn't take pictures my other helpful LGU mod, but I will try to describe it as done.

The few LGU's I have been in contact with all showed signs of spring vibration when shot. Whether or not this affects accuracy, I can only assume it does, so being that I don't cherish the heavy tar routine and Vortek, even after suggesting it to them often, has not come up with an LGU kit as of yet.

I did the next best thing by taking a piece of shim stock at .003 or 4 thousandths if I recall and fitting it into the piston. It still allows the spring to expand when compressed and takes up a lot of the oversized wall space between the spring and the piston when the spring is released. I folded the front end of the shim inward and added a proper size washer that sandwiched the folded section of the shim between washer and front of the piston. Doing this insured the shim didn't move when the spring is released. It sort of emulates the plastic spring cover that Vortek kits have.

A light coat of molly grease on the spring then reassembly reduced vibration to zero.
 
Upvote 0
I have posted my trigger mod a few times so I will not get into that area again, but it does involve much of the same things Johnny Piston did.

Too bad I didn't take pictures my other helpful LGU mod, but I will try to describe it as done.

The few LGU's I have been in contact with all showed signs of spring vibration when shot. Whether or not this affects accuracy, I can only assume it does, so being that I don't cherish the heavy tar routine and Vortek, even after suggesting it to them often, has not come up with an LGU kit as of yet.

I did the next best thing by taking a piece of shim stock at .003 or 4 thousandths if I recall and fitting it into the piston. It still allows the spring to expand when compressed and takes up a lot of the oversized wall space between the spring and the piston when the spring is released. I folded the front end of the shim inward and added a proper size washer that sandwiched the folded section of the shim between washer and front of the piston. Doing this insured the shim didn't move when the spring is released. It sort of emulates the plastic spring cover that Vortek kits have.

A light coat of molly grease on the spring then reassembly reduced vibration to zero.
Click to expand...

A tight mainspring-to-rear guide fit and snug fitting tophat to the a)piston rod and b) mainspring will usually yield a low vibration shot cycle. If you address these two areas, you may find that a piston sleeve is not even necessary. 


Out of all of the LGU’s I’ve owned past and present (total of 4) only one had vibrations but that’s because it was “hot rodded” for max FPE, with a piston full of weights and a loose FAC OEM spring to boot. Luckily it was easy to fix🤓




 
Upvote 0
I have posted my trigger mod a few times so I will not get into that area again, but it does involve much of the same things Johnny Piston did.

Too bad I didn't take pictures my other helpful LGU mod, but I will try to describe it as done.

The few LGU's I have been in contact with all showed signs of spring vibration when shot. Whether or not this affects accuracy, I can only assume it does, so being that I don't cherish the heavy tar routine and Vortek, even after suggesting it to them often, has not come up with an LGU kit as of yet.

I did the next best thing by taking a piece of shim stock at .003 or 4 thousandths if I recall and fitting it into the piston. It still allows the spring to expand when compressed and takes up a lot of the oversized wall space between the spring and the piston when the spring is released. I folded the front end of the shim inward and added a proper size washer that sandwiched the folded section of the shim between washer and front of the piston. Doing this insured the shim didn't move when the spring is released. It sort of emulates the plastic spring cover that Vortek kits have.

A light coat of molly grease on the spring then reassembly reduced vibration to zero.
Click to expand...

A tight mainspring-to-rear guide fit and snug fitting tophat to the a)piston rod and b) mainspring will usually yield a low vibration shot cycle. If you address these two areas, you may find that a piston sleeve is not even necessary. 


Out of all of the LGU’s I’ve owned past and present (total of 4) only one had vibrations but that’s because it was “hot rodded” for max FPE, with a piston full of weights and a loose FAC OEM spring to boot. Luckily it was easy to fix🤓

Click to expand...

I did make a snug fitting tophat both on the spring and piston rod. I want to someday when it is raining make a nice snug fitting spring guide also. That is the only thing this gun lacks. I can often pull a one hole 5 shot group at 40 yards as it is, but as we in tinkerology know, it can always be better.
 
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