So after searching the web A LOT I found that there was no instructions on how to improve the mossberg 702 trigger... safely. So after a little experimenting here I am to bestow my knowledge.
In this instructable I will address the trigger pull creep and trigger pull force. I have reduced the the creep by about 3/4 and the force needed by about half. I unfortunately didn't measure the creep before hand but it is down to about an 1/8" which for everyone with a 702 or 715 (same gun different look) you know the trigger has a lot of slack. As for the trigger pull using a crude measure and the feel of the trigger, it is reduced by half. By my observations it cannot be reduced much more this way without compromising reliability and safety.
What you will need:
To take the gun apart:
- A Philips head screwdiver
- A punch
To take apart the trigger group:
- A very small punch (like a small nail)
To make the spring:
- a finishing nail
- a digital caliper or micrometer
- a 0.114" diameter nail as a arbor
- 0.039" music wire about 6" long (the store had it listed as 0.037")
To reduce the trigger creep:
- a flat piece of metal from about 0.026 to 0.032" thick
- a digital caliper or micrometer
- super glue
and to reassemble the trigger group:
- a skewer approx. the size of the trigger group pins
- and some other strong pushing instrument.
Now onto taking the gun apart.
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Step 1: Taking the Gun Apart, Down to the Trigger Group
Picture 1: Remove bolts holding the stock to the receiver. if you have a mossberg 715 see your manual. then with a little force separate the two parts.
Picture 2: Punch out the front pin (the one closest to the barrel)
Picture 4: While pulling back on the bolt, rotate the trigger group downward.
The bolt should still be in the receiver and the trigger group should rotate freely, then remove the rear pin as seen in picture 5.
Step 2: Taking Apart the Trigger Assembly
Remove the foremost pin first, it is not holding anything but stops the hammer from going to far forward. after that remove the hammer pin, make sure the hammer is released as shown in the picture and cup your hand around it as you remove the pin so the spring doesn't fly off on you.
now for the annoying part:
Remove the third pin slowly, it holds the trigger and the spring loaded seer. cup your hand over that area as you remove it so it doesn't launch the trigger or seer and their free-floating pins.
once you have those all freed up onto the modifications.
Step 3: Trigger Force Fix
In the seer their is a torsion spring in which the wire thickness is 0.047". with springs one way of lowering force is to have a smaller diameter wire. I went to a nearby hobby shop and picked up some music wire, music wire is more of a type then a use. music wire is spring wire, I used a piece with a thickness of 0.038" (I think the specs said 0.037")
I made a simple torsion spring rig using a nail that is 0.114" in diameter as a arbor. I will not go too much into detail about making springs but I made the replacement spring the exact same as the original but with smaller wire. make sure the spring has all the bends in all the right places.
Note: You should be cautious if you chose to use a wire thinner then 0.037" because the spring arms may not have enough strength to retain their shape while under tension within the trigger mechanism. the negative repercussions could be: Hammer doesn't catch when cycling, trigger doesn't reset resulting in a no fire until fixed, or worst case hammer does not get held well enough and can slip off resulting in unintentional firing of the rifle.
Step 4: Reattaching the Seer
This, as well as the trigger is a pain the first...couple of times, attach the spring with the free floating pin as shown in picture 1, the hook in the spring should come up and be visible from above if inserted correctly. first insert the trigger pin just into the frame but not into the canal, then place the seer nose down and hold it down above the safety with any improvised rod, I used a round file with another instrument press down the back end, yes they did not make the trigger assembly easy to work with, and now while you are holding down both ends and having the spring in the right spot push the pin into the seer. don't push it all the way through yet... it get more fun in a bit.
Step 5: Trigger Creep Fix
I did some experimenting and I admit there is still room for improvement but I did not have a adequate piece of metal. 0.039" is too thick, the trigger will not reset everytime. I had a piece of metal, I believe it was a street sweeper bristle, it is 0.026" thick. this proved to be slightly under the optimum thickness. by my estimate 0.032" would be about the limit of thickness"
Once you have the metal you wish to use this part is simple, take super glue and glue a small piece right above the corner on the front of the trigger.
Step 6: Installing the Trigger
This is one of the biggest PITA, assemble the trigger as it is in picture 1. now this part is hard to explain. place the trigger down through the seer (which is being held ever so slightly by the pin) and then press down the front of the seer with a finger or whatever you have, if you do not you will NEVER line up the trigger hole with the trigger pin. This part took me a while to get right so stick with it you will get it. I used a skewer to help align the pin hole and then pushed the pin the rest away through from the other side.
Horrey, the hardest part is over!
Step 7: Reinstalling the Hammer
first make sure the safety is off, it will be impossible to install the hammer if the safety is not off.
With the spring on the hammer spring guide, point it forward as seen in picture 2, you have to use some force to align the hammer hole with the pin hole but it is A LOT easier then dealing with the trigger. then replace the last pin, the one slightly above and in front of the hammer pin.
Make sure to test your trigger, pull back the hammer until it locks in place, pull trigger, it should release the hammer, without releasing the trigger pull back the hammer again until in locks in place. release trigger and pull again it should release the hammer, if not the piece of metal you used is too thick and it is not allowing the trigger to reset fully. It isn't necessarily your fault it could be manufacturer variance. I may update this instructable with detailed measurements of the trigger, if anyone mentions any issues.
Step 8: Reattaching the Trigger Group
Cock back the hammer on the trigger group,
take the little weird shaped plastic piece and place it in the receiver as shown in picture 3.
Put the rear of the trigger group by the plastic piece, and insert the rear pin. That plastic piece does not like to stay in its place, just make sure it is in correctly. then while pulling back the action (which if you followed my instructions should still be in their properly) push up on the trigger group, which should push fully up until the pin hole lines up, release the action slowly and it should move fairly smoothly forward.
Then insert the front pin and then reattach the stock to the receiver. You should now have a dirt cheap .22 rifle with very little trigger creep and about 3lbs trigger pull.