M&P .22 Pistol Assembly w/tips and tricks(Fixed the pictures)
Lets start with the perfunctory safety check. Unload your gun and check for an empty chamber zzzzzzzzzzzzzzzzzzzz.
Field strip the pistol.
Tip - Observe how the safety lever flanges are held between the plastic frame and the metal breech/trigger/slide rail assembly and the order of the parts, I don't show assembly instructions for these, they are simple enough.
Drift out the two roll pins, I use a 1/8" pin punch.
Pull or gently pry off the safety levers, they come straight off. They are held on by having the flange retained between the plastic pistol frame and the metal breech/trigger/slide rail assembly.
Unscrew the two side plate screws and remove the side plate. I find it helpful to lift the slidelock lever when removing the side plate. After removing the side plate the parts can be lifted out.
Tip - After many assemblies and disassemblies I found it was easiest to hold my gun - oriented as pictured above - in my left hand, fingers over the top so that I could lift up the slidestop with my index finger making the side plate removal easier.
The sear disconnector has a groove cut into it that hooks onto the linkage bar so you will need to pull the linkage bar out of the channel a little to unhook it. Don't let that spring get away.
You should be close to this:
Now is the time to polish any parts you desire. I set up to polish but after looking at my hammer and sear, it looked fine so I passed on polishing. More on this at the end.
This is a photo of the trigger blade modification I copied from a forum. This modification defeats the trigger safety that is dysfunctional in my opinion and promotes excessive trigger finger movement farther forward than is necessary for the mechanism to reset. I studied the trigger blade and selected the spot that looked like it had plenty of plastic to support the pin and would not compromise the mechanical strength of the trigger. Remove the small spring that is inside the trigger joint.
I gently secured the assembly in a vise in such a way as to have the vise apply rearward pressure to the meta-trigger blade keeping it in its maximum rearward position while drilling. Notice the use of machinist parallels to keep the assembly from rotating downward during drilling. You can use any reasonably straight material as parallels but I would strongly suggest you use something to get a nice perpendicular hole. Another reason parallels are HIGHLY recommended is, if used, you will not need to tighten the part into the vise. The parallels will provide support for the part instead of the vise jaws, the vise jaws are mainly for positioning. I used a micro drill bit that was .035 to drill the hole.
For the pin, I used a length of paperclip wire that was .040. I sharpened one end of the wire and set the assembly on a piece of scrap wood and gently tapped the wire through the trigger blade into the wood. When the wire was completely through the width of the blade I cut the wire to length on both sides leaving a few thousandths and then peened each side flush.
I'd like to show the function of the trigger assembly and some of the related parts.
The trigger assembly performs MANY functions. Personally, I don't care for this approach, a real Rube Goldberg design IMO.
1) Locks the slide open manually
2) Locks the slide open when the magazine is empty. This sits in a cut-out on one
side of the magazine. When empty, the bullet follower in the magazine pushes
up on this and locks the slide open.
3) 3a Trigger blade. Drives the linkage bar rearward performing many
simultaneous functions. The linkage bar, at position 3b, pushes against a small
cylindrical boss on the side of the sear to release the hammer.
4) Pushes up on small bar via a ramp to lift the firing pin blocking bar in the slide
out of the way of the hammer.
5) Safety. This hooks onto the trigger linkage bar preventing the bar from moving
rearward when no magazine is present. I will show what I believe to be the
best sequence and proper installation of this piece but I chose to leave it out
of my gun.
6) Safety. 6A is where part 6b blocks the rearward movement of the trigger
linkage bar when in the upward position. I have the actual
safety - part 6b - positioned incorrectly in the photo, it belongs at
position 6a in the photo. When in the downward position the linkage bar is
free to move rearward.
7) Slide actuated sear disconnector. This pin is under spring pressure and pulls
the trigger linkage bar to the left - when shooting - when the gun is in
battery. Also while in battery, a space cut into the slide allows the pin to protrude out the left side of the metal frame proud the rail's track base.
When out of battery the slide runs over the pin pushing it, and thus the trigger linkage bar, rightward
disconnecting the trigger linkage bar from the sear boss allowing forward
movement of the sear for reset.
OK, lets put it back together.
Tip - I recommend having a pick set available. I find a pick set indespensable when working on my guns
Tip - Don't forget to lube the parts with your favorite lube before installing. I like moly for steel to steel, e.g., sear/hammer, steel to steel pivot pins and the bar/ramp area - #4 in photo above - on the trigger linkage bar that raises the firing pin blocker bar.
Tip - I work with the frame about a 1/2" off the work surface. Experience has convinced me it is MUCH easier to keep some of the pivot pins length protruding below the frame out of the way, this also allows for part wiggle without them becoming unseated.
The trigger assembly is the first part installed, all the other parts build on this.
I use a hobbying clip to hold the slide lock spring in position while seating the trigger assembly. You can just see the last coil of the spring in the photo. I don't worry about positioning the trigger return spring until the assembly is in position and the clip holding the spring is removed. Again, I only have about half of the trigger pivot pin above the frame so that I can finesse the assembly into position. It is difficult so don't be discouraged, you'll get better at it with practice. Once the assembly is in position I remove the clip and use a pick to rotate the trigger return spring into position and then push the pin ONLY flush with the top of the trigger blade. The trigger return spring is held in place by the pistol frame underneath the breechblock. Mine had a wear mark on the finish indicating the factory's installation location. Once the trigger assembly is in position you are well on your way.
Next I install the slide sear disconnector. You will have to hook the slotted end of the pin onto the bar with the tip getting inserted into the blind hole on the right of the frame all while retaining the spring. Make sure the slot cut into the pin lays perfectly flat on the bar or the chisel tip that protrudes onto the rail will not be oriented correctly. It was the most difficult part for me to install, hope your installation goes smoother.
Tip - I bent a paper clip in the shape of a long "U" to retain the spring, lifted the bar out of the channel with a pick and left the pick underneath the trigger linkage bar until I hooked the pin and then retracted everything.
Next I install the "empty-magazine-well safety". Orient the torsion spring into the part's slot properly. Slide its pivot pin into its hole and drop in. The long side of the spring fits into frame slot indicated. Pivot pin hole is directly above. Hook drops into trigger linkage bar like a piece of a puzzle. Again, I show the installation but I left this out of my gun.
Next is the sear. Position pin and return spring in part. This is another uncomplicated install. Drop in and seat the spring as shown. The thick arrow shows an inserted picture of the sear and sear boss that is pushed by the trigger transfer bar at the location of the thin arrow. Wavy arrow shows where to seat sear return spring.
Firing pin blocking bar lifter? Note the orientation of the radius at the pivot pin hole just above the trigger linkage bar. The arrow is just to show the part being discussed.
Tip - You could probably reduce the weight of the trigger pull by excluding this but you will have to remove the firing pin blocker assembly in the slide. I'm using my pistol for defensive pistol practice which will include drawing from a holster so I feel its best to leave it in place for my intended use. YMMV.
Now the hammer. Align and drop in with pivot pin as shown. About the only detail of note is to place the hammer rod in front of the retaining wall of the sear return spring.
Side plate. I install the side plate at the angle shown. I'll push the pivot pins flush with the parts to make sure the plate can rotate smoothly over the top of them. I place the back end on the large sear disconnector pin first and rotate it up and underneath the slide lock lever WHILE lifting the slide lock lever FROM THE FAR SIDE. Need 3 hands yet? When I place the side plate on the large rear pin, I pick up the entire assembly as described in the beginning, with my left hand over the top of the entire assembly, not underneath it as though I were to hold it in my palm. Gripping it over the top allows me to hold it and work the lever with my left index finger while moving the side plate into position. Think this is too much information? Let me know your "best practice".
Tip - I put the slightest bit of threadlocker on the tips of the side plate screws a few threads from the end when I knew I wasn't going back in for a while.
Tip - For easiest installation of the completed assembly, the hammer should be upright so there is the least amount of pressure on the hammer spring in the plastic frame.
Tip - I use two finishing nails of the approximate diameter of the roll pins, cut to length, to hold the complete assembly in place when assembling/disassembling and working on the gun.
With clean up, lube and removing the empty mag safety the Wheeler trigger pull gauge shows a hair over 3lb.s over three pulls. I'll leave it alone.