Topic: Trigger travel reduction (Read 1516 times)

Kilibreaux · « **on:** May 05, 2011, 02:21:38 PM »

Dizzny1,

I have attached some photos to help explain the trigger travel reduction mod.

You can actually get away with backing out the upper screw because it can't back completely out when the trigger housing is installed in the grip housing.

Hopefully the photos will clarify my lengthy explanation, but be aware this can only be done if you have removed the firing pin block and no longer need the upper portion of the plate...as you can see in the photo. I removed approximately .210" of trigger travel prior to sear release. It took me about 5 minutes to grind out the recess in the plate and complete the mod. The backed out screw is really not needed since the trigger housing "halves" are held tightly together while inside the grip housing. When I get time I'll go buy an 18mm M3x.5 machine screw to replace it, but as it it works perfectly!

Now install as trigger stop to prevent the trigger snapping further back during disconnection and the GSG ends up with a VERY crisp (totally safe), short-stroke trigger.

I want to thank you for proposing the idea because I too had thought the trigger had excessive movement but had not considered that once the firing pin release plate is cut down and no longer needed for that function, the initial 1/4" of trigger travel is also no longer needed.

Microgunner · « **Reply #1 on:** May 05, 2011, 03:18:03 PM »

Outstanding. Thanks.

dizzny1 · « **Reply #2 on:** May 05, 2011, 09:02:07 PM »

You are the man!!! oh hey 1 last question, I cut down my plate all the way to where it starts to bend, all I have is the bottom portion... is this still going to work? I did take out that safety you suggested

Kilibreaux · « **Reply #3 on:** May 05, 2011, 10:45:14 PM »

Absolutely your plate will work. I left my plate "tall" because it provides a mounting point for potential future mods, but cutting the plate down "level" won't negatively impact this mod.

I'm quite impressed with how much better the trigger feels now. The trigger always seemed mushy and indistinct, but now it has just the right amount of slack. Thanks again for the idea!

dizzny1 · « **Reply #4 on:** May 05, 2011, 11:06:12 PM »

no prob... right now I am freaking stuck trying to get this hk selector switch to work, got the hole drilled out right and the trigger pack set correctly in my sef lower, but for the life of me I am having a hard time figuring out EXACTLY where to dremel the selector, and I am trying to get this done and assembled to carry it to the range tomorrow!!!!

dizzny1 · « **Reply #5 on:** May 06, 2011, 04:15:34 AM »

GOT IT!!! and i did our mod, going to the range tomorrow will let you know how it goes

dizzny1 · « **Reply #6 on:** May 07, 2011, 12:44:39 PM »

All I can say is WOW. Our little mod did wonders!! Nice brisk trigger now, not a"hair" trigger but has a clean break with almost no slack at all!!! 400 rounds no ftf or mishaps I completed all the following mods and the difference is night and day

Scew upgrade
Firing pin mod
Hammer strut mod
Return plate mod both top removal and slot for screw
sef lower
real H&K selector
gsg 522-5 conversion kit

Kilibreaux · « **Reply #7 on:** May 07, 2011, 12:59:35 PM »

Impressive!

I don't know why I didn't think of the trigger travel mod sooner because after doing it, it's like a different trigger has been installed!

Popcop45 · « **Reply #8 on:** May 07, 2011, 10:33:23 PM »

Wow, I 've been missing out on this (busy messing with my M1 Carbine). Great mod! I am going to get right on it.
My GSG-5 / HK94 has been shooting butter smooth since the hammer strut mod.
Killibraeux, what about a longer screw with a spacer just to keep some torque in the area of the backed out screw?

Kilibreaux · « **Reply #9 on:** May 08, 2011, 03:54:38 AM »

Popcop45,

Absolutely you can use a longer screw with small lock washers or flat washers. The original intent is to use an M3x.5 - 18mm machine screw with stacked washers to create the limiter stop, but then I realized I could just back the existing screw out in order to get the mod done and try it out. When the trigger housing is installed inside the grip housing it is held quite tightly together so once really could get by with the backed out screw, but it's not as refined a solution as the longer screw with washer stack.

Popcop45 · « **Reply #10 on:** May 08, 2011, 11:02:15 PM »

Killibreaux,
Do you think this will put a little extra wear on the sear spring since it will have slight constant depression? I was thinking maybe a slightly stronger spring? Your thoughts...

Kilibreaux · « **Reply #11 on:** May 09, 2011, 02:40:04 PM »

Well, actually the sear spring tension remains unchanged.
You see, the first 1/4" of trigger travel is purely for the purpose of moving the firing pin release lever (plate) forward, and secondarily retracting the trigger bar out from beneath the sear arm so as to allow the sear arm to move downward and release the hammer. During this rotation the sear is held solidly in contact with the cocked hammer due to the independent nature of the sear arm (housing), sear spring, and hammer spring, AND the trigger return spring via the firing pin release lever (plate) that serves to "set" the trigger forward of where it might be precisely to create "room" for travel to move those parts prior to sear release. Basically the trigger moves back, but the sear does not change position until a point is reached where the sear arm is pulled out of engagement by the trigger once the two have reach their "hard contact" interface.
Now something you CAN consider with respect to the sear spring is adding a secondary coil of larger diameter around the primary spring...and this serves TWO important functions. The first is to increase "lifting force" on the sear arm during disconnection to eliminate multiple fires (and it works). Certainly this COULD be done by using a stronger single coil sear spring, but there is a secondary "benefit" of the dual coil set up. Because the second coil rests between the upper and lower surfaces it can also function as a trigger limiter...meaning it limits how far the trigger moves to the rear and thus becomes an "over travel stop." Also, we all have thousands of click pens lying around with springs in them that are easy to test versus going on the hunt for a special spring of equal diameter to the sear spring, with a heavier rating, thicker wire, longer length, etc.
As you know the GSG has a rather long, mushy, indistinct trigger both ahead of sear release due to the internal design to use the initial trigger travel for secondary and tertiary functions, and AFTER sear release simply due to free travel with no over travel stop or limiter other than the trigger contacting the housing.
The instant you eliminate a full 1/4" of front-end trigger travel you be even more acutely aware of how far it travels rearward AFTER sear release and the disconnector "snaps" also letting the trigger "jump" further back.
Because of my previous modification to the sear spring - essentially making it a dual coil set up, rearward travel was already limited so once I did the current trigger travel mod my trigger suddenly became amazingly crisp and precise...slight takeup, nice snap release, slight overtravel.

Now that you've mentioned the sear spring however, I have an idea...one can actually play with different length outer coils...(why not they come from click pens and so should be easy to find), and end up limiting trigger over travel quite nicely. Another way might be to look at drilling a small hole right beside the sear spring well and threading it to accept a small set screw which would allow one to finely tune trigger movement after the snap. Of course there are other ways to go about adding a trigger over travel stop, but as I said, trying a click pen coil spring...clip a coil at a time and fit it, then stop when the trigger will move far enough to release the sear (and a tad more movement).

Popcop45 · « **Reply #12 on:** May 09, 2011, 06:57:45 PM »

Thank you for the detail explanation. I am done with my mod. Took me a little while since at first I left the screw out too far. A quick trip to Ace for the longer screw and I was done. The trigger slack is completely gone. I will test it out tomorrow.
Picture one shows the OEM screw too far out. Picture two shows the longer screw from Ace with a nut serving as a spacer.

Kilibreaux · « **Reply #13 on:** May 10, 2011, 10:44:39 AM »

Wow! The precision cut of your stop plate recess is amazing! I can see why you have zero slack because you held your cut outside the smaller hole. On mine I took it just a bit deeper and ended up with a tiny bit of take up.

Popcop45 · « **Reply #14 on:** June 05, 2011, 01:52:13 PM »

Well, this afternoon I shot my GSG-5 for the first time after the trigger mod - and although it preformed well, I did not like what I saw.
Heavy gun powder residue on all of the casings and on the chamber (ammo did not change).
After 22 rounds, my chamber was jet black, and the casings were two tone black and brass. Prior to the mod, one of the things I noticed and impressed me the most was how clean the chamber would stay after running several magazines through it.
Not sure what shortening the trigger pull did to make this happen. If this isn't happen to the rest of you, then it has to be because of my near zero slack.
Tomorrow I'll try to adjust it so there is slightly more slack.