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View Full Version : A Trigger Pull Theory


game_guy02
07-30-2004, 08:11 AM
Now, I may be headed way off on this one, but I think this might be worth looking into. A little while ago, pooptarts92 posted about a 1 mm trigger pull. It didn't work, as the sear wasn't always catching the bolt.

Now, I'm sitting here looking at my sear and bolt and thinking "Hmm, how can I make this work?" and I think I may have found the answer.

When the bolt is in position (meaning the sear is sitting in the little notch) the sear isn't angled to its full potential. You can check this by looking at the sear's angle before it is in the notch and after. On mine, it seems I have at least a 1 mm clearance. Now, if we were to, say, file that notch down so the sear rests higher, that 1 mm pull might work and not cause full-auto, and poor-cycle effects.

Let's look at this from a mechanical point of view; the full auto effect is caused by the sear resting it's lower-angled end too high, thus causing it to not fully catch the notch.
Two problems there, one, if the pin is taped, that 1 mm extra I referred to earlier might not come into effect at all, and two if that 1 mm is still there will the extra distance it must travel cause it to not work?
For reason number two, it should work, as a longer area of sear movement is the opposite of a shorter sear movement (which in this case caused a problem).
For the first problem, looking at the sear resting pin while the sear is not being pushed by the bolt, the pin is being pushed back as far as it can go, so tape might make it sit where it normally would, which in this case might undermine the point of the tape.
However, the fact that when the recievers are put back together that pin's push-back might be corrected or helped somewhat, as the holes on the reciever's probably aren't 100% the same.
Here is a possible solution, modding the trigger. Not your conventional mod, but on top of the spring casing on the trigger itself. If the tape doesnt work, we can always make our trigger trip the sear early. This seems as though it would take something paper thin, but that is one piece of paper quicker then it not being there. We could even try adding a piece of thin cardboard, which is roughly the same width as the tape would be. (The occuring problem with this is that the cardboard might get roughed up by the sear and eventually beocme a junky mess) If that doesn't work, we can try adding another wrap of tape to our pin.

The theory behind all this is that if we allow the sear more room to catch the bolt, we can make our pull shorter without it going full-auto. I guess what we are really looking for is that "sweet spot" where the sear catches enough to keep it from spewing gas, but doesnt get to friendly and refuse to leave it's good pal the bolt.

If there is any adventurous tippy owners out there willing to give this a shot, please contact me as I would like to know if this works or not. Also, the link to pooptarts' thread is: http://pbreview.com/forums/showthread.php?s=&threadid=246039 . Thanks for reading.

ace6160
07-30-2004, 08:33 AM
I kind of get what you're saying. You might want toget pics up, if you can.

Now, we just need someone to try it.

snap shoot
07-30-2004, 08:37 AM
Yes yes I see what you are trying to do and it just might work. Like ace said try to get pictures and draw arrows where everything goes. Once that is done my question is anyone got a 98 to spare?

game_guy02
07-30-2004, 08:57 AM
After spending a half hour searching for a pic of the specific area of internals we are looking at, I have concluded A) I suck at looking and B) I wish I had a webcam. If anyone can get me a nice photo of the bolt / sear area of internals, I would be grateful.

game_guy02
07-30-2004, 09:46 AM
This is the best pic I could get. It is one from model98.net for silencing your sear spring, so credits to the owner of the photo, and please don't be mad at me for using it. Anyway, here is our breakdown:

The Infamous Bolt Notch
http://img.photobucket.com/albums/v449/game_guy02/searnotch.jpg

This is where the sear rests while it is angled. The theory is that if we file this part down, the sear will get the extra room it needs for a shorter trigger pull.

The Trigger Spring Casing
http://img.photobucket.com/albums/v449/game_guy02/springcase.jpg

This is the part where that cardboard would be attached to. It is shaped like a blocky "U" and might be tricky to glue things too.

That Darned Sear Resting Pin
http://img.photobucket.com/albums/v449/game_guy02/searpin.jpg

This is the pin that gets pushed back when the sear has no pressure from the bolt notch. If we put tape on it, it might make the sear go to where it would normally sit, or perhaps farther.

The Sear Itself
http://img.photobucket.com/albums/v449/game_guy02/thesear.jpg

This one oddly shaped piece of metal is the devil to this mod. The difference between my gun and this picture, is that my sear spring is really an orthodontic elastic.

The Extra MM God Gave Us
http://img.photobucket.com/albums/v449/game_guy02/extramm.jpg

This is the basis of this mod. Due to the picture, I can't show exactly the length you will get, so strip your honey down and look for youself. look at how high the tip of the sear is with and without it being in the notch. If we can get that mm to be used to it's full potential, we might get a very short pull.

Unfortunately, this picture doesn't show one component of the mod; the spring that holds the trigger in position. It is the one located at the forwardmost part of the trigger inside the gun. If this mod is to work, I figure the stock spring will be needed, as it is the stiffest and would keep the trigger from tripping the sear too easy.

EDIT: The pic of everything combined is too large a file. Please hold up.

game_guy02
07-30-2004, 09:54 AM
The pic is shrunk. Enjoy.

E r y k
07-30-2004, 10:26 AM
Originally posted by game_guy02
After spending a half hour searching for a pic of the specific area of internals we are looking at, I have concluded A) I suck at looking and B) I wish I had a webcam. If anyone can get me a nice photo of the bolt / sear area of internals, I would be grateful.

ok lemme do that... im giving my gun a make over anyways

game_guy02
07-30-2004, 10:30 AM
Oh lovely. If you can, please take a pic with the bolt in and out from the exact same position. That is one of the more crucial bits.

E r y k
07-30-2004, 10:32 AM
hit me up on aim, ill delete these posts after.

Superandy12
07-30-2004, 10:45 AM
if you could guys could get me to understand what to do all do it in a heart beat

game_guy02
07-30-2004, 11:22 AM
Superandy, to do this mod you have to file down the notch in the bolt that your sear goes into. It must be filed enough so that the sear can angle to its full potential. Once that is done, you need to tape the resting pin and / or put a bit of thin cardboard (like cereal box cardboard) on the trigger case. After that, basically all you need to do is fine tune it to see if it works or not. OH! And before hand you need to have installed the triggerstop mentioned by Pooptarts in his post I linked too. I know it is a little confusing, but I would love to see if this works.

E r y k
07-30-2004, 11:25 AM
oh, and a point to watch out.

dont file it on a slant. or it will just slide over and not catch at all.

game_guy02
07-30-2004, 11:27 AM
Hmm, actually you filing the flat part upwards so slant shouldn't play too much of a factor here. Still, watch out though.

Superandy12
07-31-2004, 07:41 AM
but isnt the whole reason you have a shorter trigger pull is because the sear only needs to be moved a little to set off the bolt? the less it needs to be moved the shorter the pull.

yakitori
07-31-2004, 08:22 AM
that may create a shorter...stiffer trigger pull. If you do this, then the rear hammer pushing on the sear from that angle will create more leverage force on your sear because of the angle, and there would be more force applied toward the trigger making it a stiffer pull. The reason is normally the hammer and drive spring force pushing against the sear in the cocked position causes the pivot hole to push against the pivot pin and holds the force of the hammer and drive spring in place.

That is why I think that more leverage on your sear will make tripping it a bit more stiff.

game_guy02
07-31-2004, 07:46 PM
In regards to what superandy said; yes, the point of the mod is that. But, at the length pooptarts had his pull the sear got tripped far too easy, causing the natural vibration to make it go full auto. Think RT, but poorer. The point of what I am saying is that if we make the sear a tiny bit harder to set off, the pull can be 1 mm long as pooptarts had it. With what yakitori said; I cant really see that happening. Even so, it would be very minimal as it only causes the sear to go 1 mm higher than it usually is. The only way there would be substantial stiffness is if we caused alot of friction, and 1 extra mm shouldn't cause that.