I swapped my Q5 SF Expert Trigger into my P99 and it worked for me, but I didn't really gain much doing it (the SA was very close). The adjustable housing might be the only worthy upgrade, or modify it by drilling and tapping a hole ahead of the sear, then adding your own set screw. See here:

PPQ Adjustable Creep Conversion Guide

PPQ is the most versatile pistol for those who want to customize their pistol at home. Not only can you customize your trigger pull weight, but you can also adjust the weight of the break. And no…

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If you don't feel comfortable doing things like that, I found upgrading the trigger spring with the Match Spring made a big difference.

 

Is ”match spring” just a lighter ”trigger return spring” or something else?
And do you know the difference between the ”expert” sear housing and the ”adjustable” one?

 

What is it that you're trying to accomplish with this trigger upgrade? I'm assuming you have a P99AS....if so, the sear housings you're talking about are SA only. If you used one of those sear housing assemblies, you'd lose the DA.....you'd have a single action only trigger pull.

 

Oh, just lighter and smoother in general. I thought the DA function was connected to the shape of the trigger bar but if the new sear housings will prevent DA action I’ll have to reconsider doing this experiment.

 

I do have to apologize....using a PPQ sear housing in a P99 may not negate DA.....its a hit or miss.

Its been my experience that the P99 AS trigger is pretty nice/smooth. So, is your trigger pull not smooth?

I can also say that changing to a different sear housing assembly isn't going to do anything to affect the length or smoothness of the pull.

The trigger bar only makes contact with the sear housing when you're at the 'wall'. Not much pull left at that point....just the tiniest bit of creep and 'click'.

 

The P99 AS already has less creep and the shortest reset of ANY of my PPQ's....okay, any of my 'stock' PPQ's. 😁

If you want to reduce the trigger pull in AS/SA, then using a lighter Trigger Return Spring will do that.

If you want to reduce the trigger pull in DA, you can replace the striker spring with a Glock striker spring.

If you have a gritty trigger, there are a few things you can do to improve that too.

But an Expert 'sear housing assembly' will probably not provide enough of a change in creep or reset to be noticeable in your P99. Perform this swap on a PPQ and the answer is 'yes'.

From the internet. Expert Trigger, drop-in, Steel Frame

Upgrade for Steel-Frame pistols from polymer trigger blade to Expert Trigger with blue anodized aluminum trigger shoe.

Competition trigger with 20 Newtons trigger pull force, adjustable take-up, and over-travel. Trigger reach can be modified by choosing between trigger shoe styles flat or curved in sizes small, medium, or large.

The installation is carried out by the Walther Master Shop in Ulm and includes an optimization of the sear engagement. Trigger shoes flat/medium and curved/medium are included in the upgrade.

Item No. 2841037

To those who own a Walther PPQ or looking to purchase a Walther Q5 but are not impressed with their factory 5 pound trigger, well you are in luck. At IWA Show in Nuremberg, Germany, they unveiled the Expert Drop-In Trigger Kit designed for both PPQ and the Q5 Match series. You can adjust the pre-travel, over-travel and weight. Trying it at the Walther booth gave the impression it was around 3 pound pull with an extremely short reset.

This factory trigger kit, however, is NOT drop safe since it does not feature a trigger safety or hump in the middle.

The Expert trigger drop-in kit are available for Steel Frame, SKU# 2841037 and Polymer Frame, SKU# 2841070.

 

Okay, so I went back and found enough parts and pieces to cobble together a similar combination to what you're talking about.

I didn't have a spare P99 frame so I used:

PPQ M2 frame
PDP 'enhanced' sear housing assembly 😁
SW99 AS trigger bar assembly
SW99 'complete' upper (slide) assembly

Now, as I mentioned before, DA is gonna be hit or miss....more than likely a miss. The reason for that is because the P99 sear assembly has/includes an 'adjustable' trigger bar guide. There is a tiny hole in the top, right side of the sear assembly containing a 'set screw'. THAT screw is used to adjust the trigger bar guide (up of down) to fine tune the DA operation. If the trigger bar guide is not adjusted properly, DA will either release too early, too late or not at all.

This hole is not included in the PPQ or PDP sear housings....meaning you'll have NO way to adjust the trigger bar guide.

Now, with the above parts assembled. I can say that the trigger pull is much like a P99....meaning AS and SA, but NO DA with this conglomeration of parts. The SA 'wall' is still waaaay back there and the (creep, break and reset) was very good...but that has nothing to do with the P99 trigger bar and everything to do with the 'PDP's new factory enhanced, sear housing assembly.

The BIG takeaway is the fact that DA doesn't work. I guess you could drill and tap a tiny hole in the PDP or PPQ sear housing, insert a set screw and then you'd be able to adjust the trigger bar for proper DA operation.

Test mule.

At the wall.

After the break.

And, here's a picture of the P99 Sear assembly. Red arrow is pointing to the trigger bar guide. Green arrow is pointing to the allen screw. Blue arrow is pointing to the threaded hole in the sear housing. Gotta have this arrangement to be able to adjust the proper operation or timing of the DA pull. Releasing too early....light primer strikes...go too far the other way and the trigger bar may not release the striker.....its gotta be adjusted just right.

 

Very interesting facts. Thank you. It inspires me to research even more. It seems that there exists 2 variants of P99 sear housings with adjustability of the DA. Those with:
2662639 Gewindestift = Adjustable trigger bar guide screw

https://www.carl-walther.de/uploads/media/partsdrawings/P99_AS_268_84_50_l.pdf

and those with interchangeable fixed trigger bar guides of different heights (in german= Steuerstück ).

Despiece Walther P99 AS / P99 C AS - BORCHERS, S.A.

Despiece Walther P99 AS / P99 C AS

www.borchers.es

Maybe its old/new variant?

 

I just pulled out the PDP sear housing and installed the P99 sear housing. Man that trigger is smooth/nice.....and that's with NO oil. 😂 Now, this is just a test mule...if I were going to be shooting it, I'd be adding a little oil.

 

P99 MASTER RACE!

 

That's right, the older sear housings used a replaceable spacer. The new housings use the set screw.

The P99 AS trigger system really is awesome. AS, SA and DA. AS....long light pull. SA, trigger is positioned at mid point, lessening the length of pull. The 'wall' is distinct and very close to the rear of the frame...a 4.5 lb break (give or take), short overtravel and short reset. The P99 single action trigger pull/reset is better than the PPQ....and I'd think at least as good as the PDP....maybe better. All you're left with now is the DA pull......its around 8 lbs but can be reduced by using a Glock striker spring. AND, the AS/SA trigger pull is usually smooth, at least on the P99's I've handled. However, if there's any grit anywhere in the pull, THAT can be addressed.

You may have already seen this, buy here's a link to a thread about the P99 trigger system. Walther P99 Trigger Systems

 

This is an interesting thread. I am interested in reducing the DA pull on my P99c.

I see Glock striker springs come in a variety of weights.

Do you happen to remember what weight Glock striker spring you used?

 

This thread reminds why people bother to climb a mountain? Because it's there I suppose.

 

I bought one of each....they're cheap. 😂 The 4 lb makes the DA pull REALLY nice, but would probably produce light primer strikes (depends on the ammo). The 6 lb did reduce the DA pull and I'm still running that spring in my daughters P99C.

BTW, the impetus for using a lighter striker spring in my daughters P99C was because it was new and she was having some FTRTB (failures to return to battery) issues. I'd shoot it and it'd perform perfectly, hand it to her and she'd have a stoppage...slide would stop about 1/8" from battery...she'd pull the trigger to fire the next round and she'd have a 'click, no bang'. The 6 lb striker spring fixed that problem.

Buy one of each and try em' all.

SKU	DESCRIPTION	PRICE ($)	ADD TO CART
16161	STRIKER SPRING RP 4.0 LB for GLOCKS Pak of 1	3.49
30281	STRIKER SPRING RP 4.5 LB for GLOCKS Pak of 1	3.49
30285	STRIKER SPRING RP 5.0 LB for GLOCKS Pak of 1	3.49
32251	STRIKER SPRING STD 5.5 LB for GLOCKS Pak of 1	3.49
32247	STRIKER SPRING XP 6.0 LB for GLOCKS Pak of 1	3.49

 

I bought one of each....they're cheap. 😂 The 4 lb makes the DA pull REALLY nice, but would probably produce light primer strikes (depends on the ammo). The 6 lb did reduce the DA pull and I'm still running that spring in my daughters P99C.

Buy one of each and try em' all.

SKU	DESCRIPTION	PRICE ($)	ADD TO CART
16161	STRIKER SPRING RP 4.0 LB for GLOCKS Pak of 1	3.49
30281	STRIKER SPRING RP 4.5 LB for GLOCKS Pak of 1	3.49
30285	STRIKER SPRING RP 5.0 LB for GLOCKS Pak of 1	3.49
32251	STRIKER SPRING STD 5.5 LB for GLOCKS Pak of 1	3.49
32247	STRIKER SPRING XP 6.0 LB for GLOCKS Pak of 1	3.49

Thanks. I appreciate it!

 

Okay, a P99 AS trigger job. I once again, grabbed the same test mule I used previously....which is a well used SW99 AS 40 caliber, complete gun minus the frame. So I've got the trigger bar, sear housing, locking block...etc....everything from the same gun. I installed all the parts in a PPQ M2 frame.

Now, I'm only comparing the SA pull, specifically from the wall to break and the amount of over travel and reset. Without a doubt, the P99 has less creep than the PPQ. Overtravel is about the same, which means reset is also about the same.

Since the P99's creep is already in the land of 'oustanding', the only thing left was to work on the overtravel.....which will also improve the reset.

This was too simple....I used 1917-1911M's JB-Weld trick that he used on his P22. I mixed up some quick setting JB-Weld and put a drop on the bottom/rear of the trigger shoe. I place a piece of masking tape on the frame where the trigger shoe and blob of JB-Well would make contact....also wiped a very thin layer of grease on the tape....just as a precaution. I had a little epoxy left over so I kept checking that blob to see how soft/hard it was. It began to set up and I decided it was time to put the trigger bar back into the frame. So, I carefully put er' back in, hooking the spring up to the rear and installing the pivot pin. I continued to check the excess epoxy, and when it was pretty hard but still just a little soft, I racked the slide and slowly pulled the trigger back to the wall, and then a little more pressure and the blob of epoxy made contact with the frame......so I pulled just a little bit harder and 'click'...the striker was released. I racked the slide and tried the trigger again....back to the wall and then just a little pressure and 'click'. When that striker is release, I can't tell that the trigger moves any farther aft....its 'click' and stop. Which means reset is only a 'whisker' away.....I'm not kidding. Absolute awesome....seems like NO creep and NO overtravel and maybe a 1/16 or just a whisker more to be back forward to 'reset'.

Once again....ALL stock parts/springs etc. .... well used and broken in though.

Check out the concave curvature on the bottom of the blob of JB-Weld....I mean trigger stop.
That shape conforms PERFECTLY to the frame.

And here we are, after the break and with the trigger stop against the frame. Compare this picture to the one in post 10....last picture 'after the break'. The shoe is against the frame. This may not seem like much, but you'd just have to feel it.....the reset is a 1/16 inch or so forward.

 

We are not worthy!