Trigger Improvement - TT33 & M70A

[Ganderite]

My M70A had a 8.5 pound trigger. Just too heavy.

I reduced it to 6.5 pounds (heavy, but acceptable) quite easily and the same technique would work with a TT33.

Remove the slide and lift the hammer assemble out of the frame.

After removing both grips, one can see the magazine disconnect piece on the side of the frame. It is a spring loaded tab that engages the cut out notch on the trigger bar.

In this picture you can see that I have pried it out a bit with my screw driver.

I am not a fan of magazine disconnects, so I just pried it straight back and it broke off cleanly.

If you have a TT33, ignore that step. It does not have a disconnect.

In the back, inside of the backstrap is a vertical spring plate that provides the trigger return pressure. A lot of trigger return pressure, which you feel as a heavy trigger.

Push the top of the spring in and let the trigger drop down.

Then wiggle the trigger back and down and out of the pistol.

Pull the spring up and out of the frame.

Note that the small end goes at the bottom of the frame, hooked behind a cross pin. The larger end bears on the end of the trigger bar.

The flat piece of steel is a spring. I put it in a vice and easily filed it skinnier. This reduced the trigger pressure by 2 pounds.

This is what it looks like, re-installed.

The right end here is behind the trigger bar.

 

[edojan]

Thanks for the idea and the pics. When I bought my Zastava M70A the first thing I did was ridding off of the magazine safety but I never thought about filing the spring. Also one of these days I am planning to gently stone the hammer / sear mating surfaces. This should reduce the pull by another 1-1.5 lbs

 

[Ganderite]

I am afraid to touch sear surfaces. I have done it and made things worse.

 

[edojan]

I am afraid to touch sear surfaces. I have done it and made things worse.

Altering the surface geometry and the angle can certainly be dangerous. However, using a pro fixture + quality stones + a reasonable process should produce the desired outcome. I am using PowerCustom series II fixture with Boride stones. The key is to stone both surfaces (sear and hammer) at the factory "zero" - that without altering the angle. Even if the factory angle is slightly positive I leave it as is, if it is slightly negative (like on some Chinese SKS) I would then bring to neutral to make it safer. I just finished a trigger job on my HiPower turkish clone which reduced the pull by about 2 lb.
Also, here is an my earlier post on tuning NP34 https://www.canadiangunnutz.com/for...34-SRT-trigger-job-and-tuning-(picture-heavy)