Blackhawk's Kel-Tec P11 Trigger Job

[Blackhawk]

(The original of this was posted on TFL on 2/17/2002 at http://www.thefiringline.com/forums/showthread.php?s=&threadid=102735 I'm reposting it here for future reference.)

On my P11, the end result of these modifications was trigger travel of 0.55", negligable overtravel with the trigger breaking just short of contacting the grip, and trigger pull force of 6.5#.

The trigger job permanently modifies two parts, the trigger bar (260) and the hammer (271). The hammer spring pin (273) is replaced with one you make. (See http://www.kel-tec.com/new_page_2.htm for the parts list.) The modifications should be done in the order presented below. Before starting, be sure that you're intimately familiar with disassembling the pistol all the way down to removing the frame from the grip, the transfer bar, the trigger bar, and the hammer. Reassemble, then do the whole drill again and again while studying the parts until you understand how this ingenious machine works!

If you don't have a fair amount of mechanical aptitude, mechanical skill, and patience, don't do these modifications.

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[Blackhawk]

1. Trigger length of travel. To adjust it, you will need an accurate measuring device, such as machinist's calipers, accurate to 0.001", a fine taper (triangular section) file, magnification, such as a jeweler's loupe, and a lot of patience.

The trigger "length" of travel is a function of how far the trigger bar has to move from the time it engages the hammer until it disengages the hammer due to the hammer's rotation. This adjustment involves modifying the hammer, and it should be done very conservatively. Remove too much metal, and your hammer will be junk. It's far better to adjust it a little at a time, measure, adjust, measure, etc., than to try to get what you want in one calculated step.

Remove the frame.

Remove the slide stop and slide stop spring since they won't be needed until you're ready for final reassembly.

Attach a rubber band to one end of a regular paper clip. Place the paper clip against the trigger bar and pull the rubber band around the frame and over the other end of the paper clip near the hammer. Place another paper clip/rubber band combo forward of the first one. These retain the trigger bar in its operating position and allow it to engage the hammer normally. The paper clips are very loose against the frame -- they just act as the grip vis-a-vis the trigger bar.

Use another paper clip and rubber band to simulate the hammer spring in action. Hook the paper clip into the eye of the hammer spring, attach the rubber band, and attach the other end of the rubber band to something substantial.

What you're going to be doing with the rubber bands and paper clips is make a "fixture" so you can study and measure the interaction among the trigger, the trigger bar, and the hammer. You'll be able to hold the frame with one hand and repeatedly pull the trigger with the other.

Carefully use a bit of masking tape on the inside of trigger guard to mark the center of the tip of the trigger above the guard, but be sure to take up the reset over travel (the right point is where the trigger bar won't move forward without rotating the hammer). Raise the frame against its simulated hammer spring (formerly called a rubber band), and slowly pull the trigger, noting the exact point where the hammer releases. Mark that point on the trigger guard with another piece of masking tape. That's the original trigger length of travel, which can be shortened but not lengthened.

Measure it with the calipers, and write the measurement down!

Remove the trigger bar and hammer from the frame. Hold the two parts in their relative operating positions, and observe exactly how they work together. You will see that if you file the hammer and remove metal from where the trigger bar engages it, the release will be earlier effectively shortening the trigger length of travel. There's no great trick to filing the hammer beyond common sense. Make sure you file the edge so it remains square -- in this case exactly parallel to the hammer axis.

Use the caliper or a micrometer to measure the distance from the edge to be filed to an opposite surface on the hammer. Write it down!

Carefully file no more than 0.015" from the trigger bar engagement edge. Use magnification to make sure the edge is square! Carefully "break" the sharp edge after filing by filing a chamfer on it. Sharp edges will wear very quickly throwing everything out of adjustment. You should be able to see the chamfer with magnification.

Reassemble the frame and paper clip/rubber band fixtures. Measure everything again, including the new trigger length. Notice how filing a little off the hammer makes a big difference in the trigger length.

Repeat the filing procedure until you get the trigger length to be what you want. I recommend 0.55" because that will allow the trigger stroke to begin exactly in the center of the grip and end just before contacting the grip.

After you get the length you want, use the file to shape the profile of the hammer below the edge you filed. This isn't necessary, but it's good practice. Remember that all edges should be smooth and square. Be slow. Be careful, and take advantage of the square edges and perpendicular surfaces on your caliper to judge squareness under magnification.

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[Blackhawk]

2. Positioning the trigger travel within the trigger guard. Having a nice and shortened length of trigger travel won't be very satisfactory if it starts way forward within the trigger guard and ends with the trigger still having a long distance to go before encountering a mechanical stop. Sure, the White eraser stop works, but it works best when it's as short as possbile. These two steps will show you how to "move" the trigger travel aft within the guard, with the objective being to have trigger pull travel end just short of the grip, which makes accuracy disturbing overtravel negligible, and trigger reset overtravel end just beyond the point where the trigger resets.

Overtravel adjustment. This adjustment is made by effectively lengthening the trigger bar by filing its hammer engagement tang.

Assemble the frame, paper clip, rubber band setup. Cycle the trigger, and notice how much more the trigger can rotate before the trigger bar engagement bell crank contacts the frame in its recess. The objective is to remove enough metal from the hammer engagement tang of the trigger bar so that the hammer is released just before trigger can't rotate any more. You do NOT want the trigger bell crank to be stopped by the frame at the exact point the hammer releases because you DO want the hammer to be released every time you pull the trigger. If you go too far with this adjustment, you can easily render the pistol inoperable. The trick is file a little, measure a lot.

Every adjustment made by filing the trigger bar tang should result in a tang edge that's absolutely square with and perpendicular to the trigger bar length and that has the top edge broken (chamfered) slightly. If it's not square, the release point won't be consistent, and if the sharp edge isn't broken, it will wear very quickly.

Reassemble the entire pistol, and test it by dry firing before proceding. Use your strongest two handed grip, and make sure the trigger breaks cleanly without any jerking of the sights at that point. If you prefer, install a very thin White trigger stop to cushion the residual over travel.

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[Blackhawk]

3. Trigger reset overtravel adjustment. After the trigger is pulled, the trigger bar tang has to re-engage the hammer for the next shot. The objective of this adjustment is to have the trigger go forward just a little farther than necessary to reset the trigger bar.

The adjustment is made by using J-B Weld to build up the bell crank recess in the frame where the trigger bell crank rotates, then trimming it to limit the bell crank's rotation thus limiting the trigger's forward travel.

Disassemble the pistol, and remove the frame from the grip. Use Q-Tips and alcohol to thoroughly remove all oil or grease from the aft part of the trigger bell crank recess. The bell crank itself is liable to have oil under it, so you might to be diligent to get all oil in the area removed.

Apply enough J-B Weld into the recess area so you will be able to "carve" away the excess to provide a stop for the bell crank as though the aluminum frame had been machined the way you wanted in the first place. Position the frame with the bell crank end angled up and the trigger angled up so the J-B Weld doesn't flow toward the bell crank or bell crank axis.

Let it cure for 9-10 hours. This is important! Before that, it's too soft to work accurately, but after 15 hours it's completely cured and quite difficult to carve with a straight edged pointed tip Exacto knife blade.

Use the Exacto knife to remove the excess from the machined surfaces of the frame, then make a preliminary edge inside the bell crank recess to interface with the bell crank. You're now ready to carve the J-B Weld to precisely engage the bell crank to limit the trigger's forward overtravel.

When the firing pin is retracted in its normal position, the hammer comes to rest on the firing pin with its front face at about a 90 degree angle to the frame rails. When the slide is removed, the hammer rotates further forward of that point because there's no firing pin. You need something to hold the hammer in the same position it will be in when the gun is assembled.

For this, you need a "gauge" go fit between the frame and the hammer to substitute for the firing pin. Straighten a paper clip, bend it in half so the U in the middle is about the same width as the hammer. About 1/4" from the U, bend the 2 legs 90 degrees, then bend them 90 degrees down so they're parallel with the U and the gap between them is the same width as the frame where the hammer would strike the frame if the slide wasn't installed. Let this length extend for about 1/2" to 3/4" then bend the remaining length up to be a handle for the tool. A standard paper clip's wire thickness is just a shade too thin to hold the hammer exactly where it should be on my P-11. I put a small piece of masking tape on both sides of the hammer side of the tool (the U), and the two thicknesses on the gauge position the hammer perfectly!

Assemble the frame/transfer bar, paper clip, rubber band setup again. Use a rubber band to simulate the hammer spring so you'll be able to study the dynamic mechanism. Move the rear end of the transfer bar down so it's not engaged into the hammer, which can also be done by pulling the trigger until it releases. Notice that the trigger does not reset.

To see how much trimming of the J-B Weld you'll have to do, rotate the hammer back until it clicks when it engages the transfer bar. That's the reset point. Note the hammer face angle to the rails. You'll have to carefully trim the J-B Weld with the Exacto knife until the reset point is when the hammer rests against the gauge. As you get closer and closer to the proper adjustment, reassemble the pistol and check the trigger reset to make sure you haven't removed too much J-B Weld.

It's better to have too much trigger reset overtravel than not enough. Too much won't interfere with your pistol firing, but not enough could result in your not being able to reset the trigger.

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[Blackhawk]

4. Trigger pull adjustment. The normal P11 trigger pull force is 8.5#. Shortening the trigger length reduced that to about 7.5#, and this adjustment will reduce it further to about 6.5#.

The objective is to effectively shorten the trigger spring so it doesn't require as much force to fire the pistol.

The adjustment involves making a new hammer spring pin with a "dip" in it that anchors the hammer spring 0.075" closer to the slide than the standard pin does. My intention was to use 0.050" diameter stainless steel welding rod for the material. However, I prototyped them from the 0.050" diameter steel wire used to make Jumbo paper clips, and the prototypes have been flawless.

Bend a "v" into a length of wire where the bottom inside of the v is 0.075" below the bottom of the cross bars. The result looks something like this in profile ----v----. Shorten the cross bars evenly so the overall length of the pin is the same as the standard pin.

Using a small drill or burr on a Dremel, relieve the sides of the hole in the hammer spring catch (279) so the v of the new pin will go in far enough that the cross bars seat correctly into the catch.

Reassemble the pistol.

Reducing the trigger pull as in steps 1 and 4 has the effect of lowering the force the hammer applies to the firing pin. Obviously, if that force is too light, the firing pin spring can prevent an effective ignition strike on the primer. The firing pin spring has the job of preventing an accidental discharge since the hammer rests against the firing pin and it's always preloaded by the hammer spring. However, IMO, the firing pin spring's strength is a serious case of overkill so I think it can be safely shortened to give the hammer an easier time of in causing ignition via the firing pin. I've tested 6.5# triggers with the standard firing pin spring and one shortened by clipping 7-9 coils off. There haven't been any problems firing the pistol with either firing pin spring. In a CCW situation, I'm more comfortable with the shortened spring because I don't want the additional risk of light strikes. YMMV


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[Blackhawk]

Not long ago, it came to my attention that where and how to measure the trigger pull distance has been confusing.

Since the trigger is a hinged lever, if you measure its travel at the tip, the distance will be greater than if you measure it elsewhere during a full cycle.

Well, I measure it from where my finger pulls it, and that's just about in the center of the arc of the trigger.

I measure it by first putting it at the reset point, then measuring the distance from the center of the trigger to the back of the grip on a horizontal line parallel with the slide. That's the "big" number.

Then I pull the trigger until it releases, and measure from the center of the trigger to the same point at the back of the grip. That's the "little" number.

Subtract the little number from the big number, and that's the trigger pull distance.

That's also where I measure the trigger pull force, which obvously would be less if measured at the tip of the trigger.

There's nobody I know with fingers skinny enough to operate the trigger from the tip....

 

[Blackhawk]

yzguy created an illustrated set of instructions based on these, but they are, IMO, a bit more complicated. They're at http://www.1bad69.com/keltec/triggermods.htm

 

[Deles136]

Kel-Tec Trigger Mods

I accomplished these trigger mods on one P-11 and two P-40 Kel-Tec pistols by using the instructions posted by Blackhawk and the results were much better than I expected. I now have three pistols that are much easier for me to shoot and much more fun. My thanks to George Kelgren and Blackhawk for making my shooting hobby very enjoyable. Happy New Year to all.

 

[yzguy]

I like my pre-travel stop better!! no JB weld and it is adjustable at any time.... (Not that I'm knocking JB weld, I use it for a lot!!)

Thanks again to Blackhawk for the initial instructions and ideas....

 

[yzguy]

I just did some drop tests on my P-11 with the shortened FP spring (clipped off 7 coils), and I was very surprised to find that it would go off from a 3 FT drop!!

details here:
http://www.1bad69.com/keltec/droptest.htm

needless to say I will be doing more modifications and testing to improve this....

 

[Blackhawk]

Good work! What was the status of the hammer spring on the gun you tested? IOW, was the u clip used to reduce the tension, and if so, how much?

 

[yzguy]

I took a new spring (never installed) and cut 7 coils off. This was about 5-6 months ago I think (when I was doing my trigger mods). It has lived in the gun since then and probably seen 600-1000 rounds in that time.

I think I still have a factory one around, and I know I have the one that comes with the Wolf recoil springs around, so I'll be testing those as well.

the hammer spring is the new 8.5lb spring and I had the V notched Hammer Spring Pin with a .075 inch drop installed.

 

[Blackhawk]

Thanks. I'm looking forward to seeing the results of your continued testing!