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How to Increase Trigger Pull Weight?


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#1 jaykchan

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Posted 11 November 2013 - 05:33 PM

I bought a KWA M226 PTP as a way to practice trigger pull.  Unfortunately I find that the trigger pull weight of M226 is only half of the trigger pull weight of a real steel Sig pistol (not P226, but its close cousin).  Specifically, the double-action trigger pull of M226 is 6-pounds and its single-action trigger pull is 2.5 pounds.  The trigger pull of my a real steel Sig pistol is 12-pounds and 5-pounds respectively.  The difference is just too big.

I am wondering if there is a way to increase the trigger pull of M226 to match the real one.  I understand that this may increase the gas consumption; but I don't worry about this - I am not using it for airsoft battle anyway.

Would you please let me know how to do this?

Thanks in advance.

Jay Chan

#2 Chuck S

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Posted 12 November 2013 - 03:35 AM

In my M9-PTP I used a cut down Beretta 92 or M1911 mainspring (the spring inside the grip :) ).  Don't recall which but I use 19 pound M1911 mainsprings in my 9mm Beretta 92G pistols.  This brought the DA trigger weight up to just under 8 pounds matching my service pistol (with a lightened trigger) and the SA trigger weight to just under 4 pounds -- a tad light but far better than the stock KWA weight.

The gun does use a bit more gas overcoming the spring but it's not excessive.

You can use a much lighter mainspring in your real-SIG and get a better trigger.  I recall my P6 will function very well with a 19# mainspring (factory is something like 24#).  Wolff Gun Springs sells a kit with several springs you can try.  Unless your agency or department requires that 12# weight...  We had a NYC policeman in a course last month fighting the 12+ pound trigger weight on his SIG 229 (?).  Not only was the "New York" trigger there, the pistol was DAO!  Those of us with choices were shooting M1911 and Glocks.

-- Chuck

#3 jaykchan

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Posted 13 November 2013 - 06:46 PM

Thanks for the suggestion of replacing the main spring of M226 with a stronger spring.  I will look for it.  If I cannot find any, I will try the main spring for Sig.  I understand that I may need to trim down the heavy replacement main string until M226 can function properly.  If all fail, I will bring it to my local airsoft/paintball store to see if they can help.

I will not lighten the main spring in my real steel Sig.  I use it for home defense, and I cannot train with it as often as a law enforcement people or military people can do (that's why I need the airsoft pistol to supplement some trigger time).  Therefore, I am better off leaving it in stock configuration.  Having said that some other people who are in a different circumstance may be able to use your suggestion to lighten the spring of the real steel pistol and stiffen the spring of the airsoft pistol to match.

Thanks.

Jay Chan

#4 Chuck S

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Posted 14 November 2013 - 03:24 AM

Jay --

I ran thru my notes and I'm using a 16# Beretta mainspring in the KWA M9-PTP.  Cut to length to fit the airsoft pistol.  My service Berettas use 19# M1911 mainsprings which mimic the Beretta D-spring used in the DAO version.  Only reason is the D-spring was unobtainable for years and I see no reason to swap springs at this stage.

Your decision with the SIG P226.  My experience notes it will function better with a lighter mainspring.  The factory mainspring in the SIG P225/P226/P228/P229 series is a staggering 24 pounds making the DA trigger extremely difficult to shoot accurately.  I believe it is this heavy only due to a mistaken idea that a heavier trigger is "safer" for some reason.  I watched the NYC policeman in our class last month struggle constantly with this trigger in his DAO SIG.  At least yours switches to SA after the first (often wild) shot.  My P6/P225 is reliable with a 19# mainspring but this is probably too heavy for the KWA version.

The Wolff spring "pak" "contains 1 each of 16, 17, 18 and 19 pound reduced power hammer springs".  The 16 pound spring may fit the KWA perhaps needing a coil or two trimmed (I don't have the airsoft version).  Gonna be trial and error.  Let me search my parts box for some SIG springs.  My only remaining SIG is the olde P6 so any mainsprings will be surplus to my needs.

With SIG pistols there is an "old" and "new" mainspring cap setup.  Long spring and short spring.  Not sure which the KWA mimics.

-- Chuck

Edited by Chuck S, 14 November 2013 - 03:27 AM.


#5 jaykchan

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Posted 14 November 2013 - 02:35 PM

Thanks for the suggestion of the set of main springs from Wolff Gun Springs.  I think I will swap the main spring in my real steel Sig with the one in M226 first.  If this works well, I will order the same spring.  If not, I will order the set from Wolff Gun Springs.

Jay Chan

#6 Chuck S

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Posted 14 November 2013 - 03:15 PM

Give it try and let us know.  There may be differences in how the main (hammer) springs mount in the two different models.

-- Chuck

#7 jaykchan

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Posted 30 November 2013 - 09:34 AM

I have good result from a set of "Reduced Power Hammer Strings" from Wolff (Wolff Stock# 26575).  The set of hammer strings has 16-lb, 17-lb, 18-lb, and 19-lb.  They are much longer than the hammer string in KWA M226.  Luckily they can be cut short very easily using a Dremel tool with a cutting disc.  I have a good result with the 18-lb hammer string.  Now, the trigger pull of my M226 is exactly the same as my real steel Sig pistol.

That is the good side.  The bad side is that M226 becomes a single shot pistol.  I have to pull the slide for every shot.  I believe M226 doesn't generate enough power to push the slide backward and overcome the heavier hammer spring.  With a heavier hammer spring, M226 either fails to chamber the next round (like 90% of the time), or fails to push the hammer down (like 25% of the time).  Luckily my main purpose of replacing the hammer string is for dry firing (to overcome my jerky trigger pull problem).  Therefore, M226 becoming a single shot pistol is not a big problem to me.  I understand that this can be a problem for most people.  May be there is a way to ask M226 to generate more power to work with the heavy hammer string.  I don't know how though.

The other problem is that the diameter of the Wolff hammer string is a tiny bit wider than the one in M226.  It still can sit on the hammer spring strut - but barely.  The pistol still works -- I don't know for how long though.  I am afraid one day the hammer spring may become wider and slip over the hammer spring strut and the trigger will not work.  This is fine for my purpose of using it just for dry firing.  But this will not be good if someone intends to use it in an airsoft battle - you don't want the trigger to fail right in the middle of an airsoft battle.  If someone finds a hammer string that has the same diameter as the original one in M226, please let me know.

By the way, I have tried the factory 21-lb hammer string that is (Wolff Stock# 32421).  That one is shorter than the one in M226.  Therefore, it cannot fit in M226.  Seem like the hammer spring in M226 is "supposed" to mimic the new style hammer string in Sig that is shorter than the old style.  But the hammer string in M226 is actually a bit longer than the new style.  This is odd.  Unfortunately I don't have a Sig that has a new style hammer spring.  Therefore, I cannot tell if the factory 21-lb hammer string from Wolff is the right size or not.

By the way, I decided not to try the hammer string in my real steel Sig pistol because it is much longer than the one in M226.  This means they are different design.

If someone wants to replace the hammer string in M226 with a heavy one like what I have done despite the shortcomings that I have mentioned above, I have the following pointers:

1.  When you want to remove the plastic grips, the easy way is to remove the magazine, and stick your finger inside the magazine well and push the plastic grip out from the inside.  Of course, I assume that you have removed the screws.  And this is easier to remove the plastic grip in the side that doesn't have the decocker lever and the magazine release button.  After you have removed the grip from that side first, you will have an easy time to remove the grip in the other side.

2.  Likewise, when you want to put the plastic grips back, you should first put the grip in the side that has decocker lever and the magazine release button.  Effectively, we want to do this in the reverse order of how the plastic grips are coming off.

3.  Get a set of hammer springs like what Chuck has suggested.  Then you can try different weight of hammer springs.  In case you made a mistake, you can still have the other hammer springs.

4.  The goal is to have the hammer spring as short as the original one in M226.  Long hammer spring is very difficult to be put into the pistol.  However, shortened hammer spring may be too light, and defeats the purpose.  Therefore, you should not cut too short initially.  In the beginning, you should try cut it to the length that is 3 to 4 rings longer than the original one in M226, and then gradually cut it short one ring at a time.

5.  The set of hammer springs has 4 hammer springs (16-lb, 17-lb, 18-lb, 19-lb).  If the goal is to have a heavy trigger pull, you should start with the 16-lb spring first because it is _NOT_ likely to be the correct one.  Using the 16-lb spring is just to test the water to get the ball park figure, and it is not expected to meet your expectation.  In other words, it is sacrificial.  And then gradually move up from 16-lb to 17-lb, and 18-lb, and 19-lb.  In my case, I mistakenly jumped to 19-lb too soon and cut it to the same length as the original one in M226, and I found that the trigger pull was 1-lb too light.  Luckily 17-lb and 18-lb are still good - I need to keep them a bit long to have the correct weight of trigger pull though.  Remember the goal is to keep the hammer spring short; therefore, if I didn't cut the 19-lb hammer spring too short, I would prefer to use it instead of the 18-lb spring - I would have keep it a bit long (like 1 or 2 rings longer than the original one from M226).

6.  The hammer spring struct needs to insert quite far into the pistol.  The best way to make sure you can put it back in the right place is to take a picture before you remove the hammer spring.

Hope this helps someone.

Jay Chan

Edited by jaykchan, 30 November 2013 - 09:40 AM.


#8 Chuck S

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Posted 01 December 2013 - 05:45 AM

Depressing the mainspring requires a bit of force.  I suspect you've already thought of this but see if the gun will properly recoil with the 16 pound spring.  :)  Or cut coils off  either spring 1/4 coil at a time.  You may not get the trigger to exactly match.  There are ways to modify the valve in the slide for more gas/recoil.  My heavy-spring KWA M9 pistol vents a small amount of gas as it fires from a full magazine.

Wolff M1911 mainsprings go as low as 15 pounds and HK springs go as low as 10 and 12 pounds.  The M1911 mainsprings look to be a tiny bit larger in overall diameter.

-- Chuck

#9 jaykchan

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Posted 07 December 2013 - 08:13 AM

After using the M226 with a heavy hammer spring for a few days (mostly in single action mode), the trigger has become malfunction.  Now it only works in single action mode, but not in double action mode.

Mostly likely the area where the rear of the trigger bar meets the bottom of the hammer has developed excessive wear caused by the heavy double action pull weight (caused by the heavy hammer spring that I added to the gun). The excessive wear has caused the trigger bar failing to catch a short lever in the bottom of the hammer (that short lever is for double action trigger pull).  At this point, the most likely part that has the problem is the trigger bar because I can feel that the wear surface in the rear of the trigger bar is quite rough.  On the other hand, the wear surface of the short lever in the bottom of the hammer is still in good shape.

At this point, there is no practical solution of this problem.  If I replace the parts, the problem will come right back as long as I use the heavy hammer spring. The parts for airsoft pistol are not likely to be able to handle the heavy force caused by the heavy hammer spring. If I replace parts with real Sig parts, the parts may not fit; moreover, the real Sig hammer and trigger bar each is 5 to 6 times more expensive than the KWA replacement part.

Therefore, as of now, the best alternative is to leave it alone, and use the pistol for dry firing in single action mode only. This doesn't meet my original goal of using it to practice dry fire in both double action and single action modes.  Nevertheless, I can still get some use out of it - at least in single action mode.

No, I don't blame KWA.  After all, I am asking KWA M226 to do something that it is not designed to do.  If a part in an airsoft gun is 5 to 6 times cheaper than the part in a real gun, something has to give.  If they want to make the parts for an airsoft gun to be as good as the parts in a real gun, the airsoft gun will be so expensive that most people cannot afford to play with it.  I believe KWA is doing the right thing to keep the cost down.  People like me just have to find a different way to learn dry firing - may be using a real gun.

In short, there are multiple problems with replacing the hammer spring in M226 with a heavy version. The gun will stop being a semi-auto pistol (has to rack the slide for every shot). The trigger will become single action only (no more double action).  Trigger may fail to reset.

One additional info about replacing the hammer spring with a heavy version is that the trigger may not reset (like 1 out of 10) regardless if it is used in single action or double action mode.  I believe the problem has to do with the trigger-reset-spring in the airsoft gun is not strong enough to counter-act the heavy hammer spring. I will try replacing it with a factory version of a real Sig gun to see if this helps or not.

If there is any new development, I will post it.

Jay Chan

Edited by jaykchan, 07 December 2013 - 08:22 AM.





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