Pneu's 10 Easy (not so easy) steps to 1337 MPA-3 install.
ok... This is going be a little confusing so bear with me.
(aka: "let me put this into terms nobody can understand")
Here's what I do in order:
1) Get a dremmel and cut a notch in the MPA-3 where the sear will sit. I use the "Notched-Method" because it leaves a second point for set screws to mount to the "tab-like" remains. Take the notches as deep UP TO (not into) the spring clip gland. If you screw up and go a hiar too deep... quit your whining, as the clip gand that ecompasses the outer tabs should be sufficient.
2) Make the piston assembly with a "lukes piston". They fit in every way possible so perfectly and the $5 is well worth the time saved. Honestly... they fit PERFECT. Just a dot of superglue in the plunger and press the luke piston in all the way using a vice very making sure everything's squared away. wipe off the squeezed out superglue and let dry for 1.7 mminutes.
3) Push the assembled piston into the MPA-3 housing... but don't add the spring/retainer/clip just yet.
4) I place the MPA-3 in the frame about 1/8" down from the top of the frame so the sear in the open position doesn't hit the MPA-3. Next I position the piston assembly to rear of the frame just enough so you know the sear leg WILL NOT be able to move all the way forward. The MPA-3 should be snug enough in the frame at this point to stay put... but shouldn't take alot of effort to adjust position. If you're having trouble with the MPA-3 staying put in there... wrap it with a sheet or two of machinist paper or sticky notes.
5) Assemble the body, rail, sear (with clevis removed), and MPA-3+Frame using the front screw AND rail bushing.
6) You should notice the sear leg has restricted forward movement, due to the fact that you hopefully placed the MPA-3 assembly just a bit too far to the rear of the frame. This is a good thing. Now with a pointy object... press firmly down on the sear back portion (the portion that strikes the on/off and protrudes through the body).
This will press the sear all the way forward until the front leg (with the hook) imacts the uderside of the body - all AGD sears use a little bump-nub thingy as a forward stop against the bottom of the body's. Simultaneouly it should slide the MPA-3 assembly forward to the front of the frame to accomodate the full forward range of the sear.
7) Dissassemble the Valveless mag being sure NOT TO MOVE THE MPA-3 ASSEMBLY. Now what you have done should have slightly moved the MPA-3 back and a teensy bit up. With your fingers, relower the MPA-3 to 1/8" below the surface and a TEENY BIT Back for positive sear clearance. I'm talking a TEENY DISTANCE less than 1/32" - Just a hair.
Congratulations! your MPA-3 is positioned correctly for prefire sear clearance and vertical sear clearance... Have a drink to celebrate (preferrably Long Island or Black Russian - if your 21 of course).
8) Now for the set screws... I want you to clamp the sides of the frame with a visegrip real hard (as so to secure the mpa-3 by pressure though the sidewalls)
Eyeball the outside of the frame SUPER CARFULLY and your going to drill a through hole for a 4-40 set screw in these locations...
The holes go ALL THE WAY THROUGH the frame and solid "meat" of the MPA-3. Now you see why the "Notched-Method" was used for sear clearance... gives 2 more set screws at a longer torque angle for superior mountage.
Clearly... you must be fairly accurate when eyeballing. DO NOT MISS OR YOU WILL SNAP A DRILL BIT OR RUIN THE MPA-3. <--- happened to me twice
9) Once all 3 holes are made you are left with 6 holes to tap with a 4-40 tap. I assume you know how to tap. Use plenty of lube or the deep braas holes will pr4wn your tap (and you'll ruin the MPA-3. <-- happened to me once
Some frames I only drill the top set screw holes and the sear tab holes... leaving room for a bottom QEV install. In the pic above you can see the QEV modified for a rear QEV Instal with no extra frame milling and all 6 set screws (clearly the Champion of MPA-3 and QEV combos )
10) Dissassemble everything and clean shavings out perfectly. Relube the delrin piston. Reasseble everything.. and your good to go.
in the pics below, there is good shots of where the 3 holes were drilled from the outside:
As you read above, I like to put my MPA-3 about 1/8" below the surface. This provides me with a maximum height but safe sear clearance. I like to really shove it up there for more room to stick QEVs & 3 ways and to allow more sidewall coverage to use 6 set screws that bore INTO the MPA-3 rather than just 2 pinching it
However... Feel free to go as low as youlike cause your goin electro. But I do reccomend getting at least 2 set screws INTO the MPA-3 on BOTH sides (4 total) for a solid reliable setting.
And I will reitterate... The Lukes Piston Diameter and Legth is a godsend... worth every penny. I bout a dozen to stock up and have run out!
Honestly... it's the MPA-3 rock solid install that I feel really makes the frame. Well, that and a sweet 3 way, Nice LPR, Slick QEV install, Match Anodizing, and copious amounts of pixie dust.
HF GL DS,
Pneu
(aka: "let me put this into terms nobody can understand")
Here's what I do in order:
1) Get a dremmel and cut a notch in the MPA-3 where the sear will sit. I use the "Notched-Method" because it leaves a second point for set screws to mount to the "tab-like" remains. Take the notches as deep UP TO (not into) the spring clip gland. If you screw up and go a hiar too deep... quit your whining, as the clip gand that ecompasses the outer tabs should be sufficient.
2) Make the piston assembly with a "lukes piston". They fit in every way possible so perfectly and the $5 is well worth the time saved. Honestly... they fit PERFECT. Just a dot of superglue in the plunger and press the luke piston in all the way using a vice very making sure everything's squared away. wipe off the squeezed out superglue and let dry for 1.7 mminutes.
3) Push the assembled piston into the MPA-3 housing... but don't add the spring/retainer/clip just yet.
4) I place the MPA-3 in the frame about 1/8" down from the top of the frame so the sear in the open position doesn't hit the MPA-3. Next I position the piston assembly to rear of the frame just enough so you know the sear leg WILL NOT be able to move all the way forward. The MPA-3 should be snug enough in the frame at this point to stay put... but shouldn't take alot of effort to adjust position. If you're having trouble with the MPA-3 staying put in there... wrap it with a sheet or two of machinist paper or sticky notes.
5) Assemble the body, rail, sear (with clevis removed), and MPA-3+Frame using the front screw AND rail bushing.
6) You should notice the sear leg has restricted forward movement, due to the fact that you hopefully placed the MPA-3 assembly just a bit too far to the rear of the frame. This is a good thing. Now with a pointy object... press firmly down on the sear back portion (the portion that strikes the on/off and protrudes through the body).
This will press the sear all the way forward until the front leg (with the hook) imacts the uderside of the body - all AGD sears use a little bump-nub thingy as a forward stop against the bottom of the body's. Simultaneouly it should slide the MPA-3 assembly forward to the front of the frame to accomodate the full forward range of the sear.
7) Dissassemble the Valveless mag being sure NOT TO MOVE THE MPA-3 ASSEMBLY. Now what you have done should have slightly moved the MPA-3 back and a teensy bit up. With your fingers, relower the MPA-3 to 1/8" below the surface and a TEENY BIT Back for positive sear clearance. I'm talking a TEENY DISTANCE less than 1/32" - Just a hair.
Congratulations! your MPA-3 is positioned correctly for prefire sear clearance and vertical sear clearance... Have a drink to celebrate (preferrably Long Island or Black Russian - if your 21 of course). 8) Now for the set screws... I want you to clamp the sides of the frame with a visegrip real hard (as so to secure the mpa-3 by pressure though the sidewalls)
Eyeball the outside of the frame SUPER CARFULLY and your going to drill a through hole for a 4-40 set screw in these locations...
The holes go ALL THE WAY THROUGH the frame and solid "meat" of the MPA-3. Now you see why the "Notched-Method" was used for sear clearance... gives 2 more set screws at a longer torque angle for superior mountage.
Clearly... you must be fairly accurate when eyeballing. DO NOT MISS OR YOU WILL SNAP A DRILL BIT OR RUIN THE MPA-3. <--- happened to me twice
9) Once all 3 holes are made you are left with 6 holes to tap with a 4-40 tap. I assume you know how to tap. Use plenty of lube or the deep braas holes will pr4wn your tap (and you'll ruin the MPA-3. <-- happened to me once
Some frames I only drill the top set screw holes and the sear tab holes... leaving room for a bottom QEV install. In the pic above you can see the QEV modified for a rear QEV Instal with no extra frame milling and all 6 set screws (clearly the Champion of MPA-3 and QEV combos
)10) Dissassemble everything and clean shavings out perfectly. Relube the delrin piston. Reasseble everything.. and your good to go.
in the pics below, there is good shots of where the 3 holes were drilled from the outside:
As you read above, I like to put my MPA-3 about 1/8" below the surface. This provides me with a maximum height but safe sear clearance. I like to really shove it up there for more room to stick QEVs & 3 ways and to allow more sidewall coverage to use 6 set screws that bore INTO the MPA-3 rather than just 2 pinching it
However... Feel free to go as low as youlike cause your goin electro. But I do reccomend getting at least 2 set screws INTO the MPA-3 on BOTH sides (4 total) for a solid reliable setting.
And I will reitterate... The Lukes Piston Diameter and Legth is a godsend... worth every penny. I bout a dozen to stock up and have run out!
Honestly... it's the MPA-3 rock solid install that I feel really makes the frame. Well, that and a sweet 3 way, Nice LPR, Slick QEV install, Match Anodizing, and copious amounts of pixie dust.
HF GL DS,Pneu
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