Warning:  Disassembling and tinkering with your firearm may void the warranty.  I claim no responsibility for use or misuse of these instructions; proceed at your own risk!

Relieving the Magazine Well

My Sub 2k takes Beretta magazines, but both the factory Beretta and after-market magazines fit very tightly.  I relieved the magazine well on both receiver halves as follows:

1.  Completely disassemble the rifle as described above.

2.  Wrap a piece of 400-grit wet/dry paper around a magazine.

3.  Carefully sand the rails inside the magazine well on each side of the receiver.

4.  Put the receiver halves together with the screws and magazine catch to test for functioning.

5.  I also had to bevel the edge of each magazine where it met the magazine catch.

Working the Hammer and Sear

Caution:  This procedure requires special tools.  Unless you are familiar with working with hammers and sears, please do not attempt these procedures.

Required Tools

Please do not attempt to cut/polish the hammer and sear mating surfaces without the correct tools.  Without the correct tools you could round the surfaces making them unsafe and/or inoperable.  I used the following tools to modify the hammer and sear.

Tool:	Available From:
Power Custom Series I stoning fixture Used to cut/polish sear and to square front edge of hammer mating surface	http://www.midwayusa.com
Series I Ruger MKII adapter Used to cut/polish sear	http://www.midwayusa.com
Series I 10/22 adapter Used to square front edge of hammer mating surface	http://www.midwayusa.com
Coarse ceramic stick Used to cut sear and to square front edge of hammer mating surface	http://www.brownells.com
Fine ceramic stick Used to polish sear	http://www.brownells.com
Power Custom Series II stoning fixture with universal adapter Used to cut/polish hammer mating surface	http://www.brownells.com
India Stone (for use with Series II stoning fixture) Used to cut hammer mating surface	http://www.brownells.com
Hard Arkansas Stone (for use with Series II stoning fixture) Used to cut hammer mating surface	http://www.brownells.com
Marking fluid	http://www.brownells.com
13/64” drill bit	Hardware store
¼ x 20 tap	Hardware store
.094” drill bit	Hardware store
Dremel tool w/cut off wheel	Hardware store
Digital/Dial Calipers	Hardware store, http://www.midwayusa.com , http://www.brownells.com

As mentioned on the KTOG bulletin board ( http://www.ktog.org ) the sear of the Sub2k rifle is set at a positive angle, i.e. when the sear moves forward it actually has to force the hammer up against the hammer spring.  This is one reason for the very heavy trigger pull.  Also, the sear-to-hammer mating surface is about .060” deep.  In this procedure we will zero the sear angle, and reduce the amount of sear-to-hammer mating surface.  Please be aware that the only way to change the angle of the hammer and sear mating surfaces is with the proper tools.  Ok, enough harping!

Hammer/Sear Basics

How the hammer and sear mate is critical to firearm safety, and directly affects trigger pull.  Figure 1 shows a hammer and sear with a positive engagement angle.  (The angle in these diagrams has been exaggerated for clarity.)  The angle is in front of the hammer pivot point.  When the sear rotates toward let off, it pushes the hammer up against the hammer spring, hence making the trigger pull heavy, but very safe.

                                               

Figure 1:  Positive Angle                                          Figure 2:  Hammer Push Through

If the sear angle is in line with the hammer pivot point, this is a sear angle of 0^o as shown in Figure 3.  In Figure 4, notice that when the sear rotates, the hammer stays in place.  This makes for a light, smooth trigger pull.

                                               

Figure 3:  Zero AngleFigure 4:  No Hammer Push Through

It seems that the Kel-Tec Sub 2000 hammer is at 0^o but the sear is not.  This still causes some hammer push through, causing a heavy trigger.  However, there are enough manufacturing variations that you need to check each individual hammer and sear.

                                               

Figure 5:  Kel-Tec (exaggerated) Figure 6:  Hammer Push Through

Sear

Note:  You can perform this procedure by itself if you are sure the hammer mating surface is at 0^o. Set the hammer on top of a straight edge so the mating surface is parallel with the edge.  If the straight edge bisects the middle of the hammer pivot hole, the angle is already set to 0^o.  If the hammer is not already at 0^o then you must correct it first before performing these steps (refer to Set Hammer Angle to 0^o on page 7).

This procedure requires the Power Custom Series I stoning fixture with MKII adapter.  The sear seems to be cut at a positive angle causing hammer push through.  You can verify this by assembling the hammer bushing, hammer, and sear into the left receiver half.  While looking through the safety hole and putting pressure on the hammer with your right index finger, rotate the sear away from the hammer.  You need to adjust the sear until it does not push the hammer against your finger.  Remember, perform these steps only after verifying that the hammer angle is 0^o.

1.  Install the MKII adapter on the Power Custom Series I stoning fixture and align the 0^o mark to the line as described in the fixture instructions.

2.  Set the stone guide elevator until the stone is perfectly flat with the mating surface as described in the fixture instructions.

3.  Test the sear for function as described above.

4.  If there is no hammer push through, polish the sear with the coarse then fine stones.

5.  If there is hammer push through, proceed as follows:

6.  Mark the sear mating surface with marking fluid.

7.  Move the elevator up 4 clicks.  (1 click is about 1/2^o.)

8.  Use a square, coarse stone or coarse ceramic stick and stone the sear surface until enough smooth surface is showing that will be engaged by the hammer mating surface.

9.  Test hammer/sear function again.  Repeat steps 6-8 until there is no hammer push through.

10.  Final polish with a square, fine stone or fine ceramic stick.

You can now reassemble your rifle.  Using this procedure, I was able to reduce my trigger pull to a long, smooth, 6 pounds.  More than good enough for a combat weapon.

Hammer

This procedure requires the Power Custom Series II stoning fixture with universal adapter.  When performing this process, frequently check for fit by installing the hammer, hammer bushing, and sear into the left receiver half with no springs.  Visually check the hammer and sear mating surfaces by looking through the safety hole in the left receiver half.  Before working on the hammer we need to modify the Series II stoning fixture and universal adapter.

Modify the Series II Stoning Fixture

In order for the Series II stoning fixture to work with the Kel-Tec Sub 2000 hammer, it must be modified.  In this procedure you are going to drill and tap a third mounting hole so the stoning guide can be moved farther to the right.

1.  Move the stoning guide to the existing far outside hole and lock in the far right position using the ¼ x 20 hex screw.

2.  Drill a 13/64” hole into the upright at the far right side of the stoning guide adjustment hole.

3.  Remove the stoning guide.

4.  Tap the new hole with a ¼ x 20 tap.

5.  Set and lock the stoning guide onto the stoning fixture using this new hole.

6.  Install the universal adapter onto the fixture.

7.  Use a Dremel tool with a heavy-duty cut off wheel to cut a slot in the adapter mounting screw.  This will facilitate adjusting the adapter.

Modify the Universal Adapter

The universal adapter that comes with the Series II stoning fixture needs to be modified to work with the Kel-Tec Sub 2000 hammer as follows:

1.  Grind the shorter, round radius flat so there is enough metal left for the small set screw to function.  This is necessary so the stone does not interfere with the adapter when working the hammer mating surface.

2.  With the B side facing you and the ground edge at the top, install a .125 pin into the top hole, then install the hammer onto this pin so the mating surface is on the right.

3.  Install a .187 pin into the larger hole to the right of the hammer and allow the hammer to rest against this pin.

4.  Install the adapter onto the stoning fixture so that the ground edge of the adapter is to the right.

5.  Install the clamp block so the hammer does not rotate.

6.  The coarse and fine stones I purchased from Brownells especially for this jig were different widths so I had to adjust the stoning guide so both would fit.

7.  You may want to drill a .094 hole in the adapter in line with the alignment mark.  This will allow you to duplicate the setup if you want to work on another Kel-Tec Sub 2000 hammer.

Set Hammer Angle to 0^o

1.  Set the hammer on top of a straight edge so the mating surface is parallel with the edge.  If the straight edge bisects the middle of the hammer pivot hole, the angle is already set to 0^o.

2.  Set the elevator up 52 clicks from the bottom.

3.  Adjust the jig so that the fine stone is perfectly flat against the hammer mating surface as described in the instructions.  This is the reference point.

4.  If the hammer is already set to 0^o use the fine stone to polish the mating surface.

5.  If the hammer angle needs to be adjusted, move the elevator up or down accordingly.  3 clicks is about 1^o of change.

6.  Use the India stone to cut the new mating surface.

7.  Use a straight edge to once again check for an angle of 0^o.

8.  Once you have achieved 0^o polish with the hard Arkansas stone.

Reduce Hammer Mating Surface

From the factory, the hammer mating surface is about .060”.  We want to reduce it to .020” - .030”.  This won’t lighten the trigger pull, but it will make it crisp.

1.  Using a dial or digital caliper, measure from the front of the mating surface to the top of the hammer.  It should be approximately 1.247”.  We want to remove .030” - .040” so the result should be between 1.207 - 1.217”.

2.  Using a Dremel tool, carefully remove metal from the front of the sear mating surface.  Check frequently for fit.  Leave enough metal to ensure the sear will positively and safely catch the hammer.  I stopped when the measurement from Step 1 above was reduced to 1.206”.

3.  Bevel the edges of the hammer mating surface.  This will result in a crisp trigger pull.

4.  Install the hammer onto the Series I 10/22 adapter.

5.  Install the 10/22 adapter on the Power Custom Series I stoning fixture so that the front of the sear mating surface is on top.

6.  Stone the front of the sear mating surface so that it is square.  Be sure to maintain a round radius.

7.  Carefully stone the front edge of the sear mating surface to break the burr raised by steps 2, 3 and 6 above.

8.  Lubricate the hammer and sear mating surfaces with a good quality gun oil.

9.  Reassemble the rifle and test for functioning.

When you’re all through, you should have a safe, crisp, smooth trigger pull between 5-6 pounds.