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Tuning Tanfoglio Stock II Extreme


Stevec717

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I recently got a TF Stock II Extreme. The trigger was significantly better than a Stock II out of the box. All internals were nicely polished (though not perfect) from the factory. Trigger measured about 10/4 lbs DA/SA. Very clean break, no creep. Love the gun, shot it a few times then after trying a friends worked Stock II, decided it could use a little more trigger work.

So I got all the various springs and took it apart. Took some time doing additional smoothing on plunger, trigger bar, pivots, etc.

Springs-

Changed recoil spring to 8 lb.

Changed plunger spring to 20 lb (24 lb stock)

Changed hammer spring to 14 lb (16 lb stock)

Note: I did not use the lightest springs for any of these, usually middle weight.

It already has the extreme hammer, sear, and firing pin.

The trigger turned out beautiful and measured just under 3 lbs (2.8) in SA and 7 lbs DA.

First and second time out it functioned perfectly (about 150 rds).

Third time out I had a few (about 1 in 10 or 15) light primer strikes. I use all Winchester Sm Pistol (9mm)

So I though maybe I was too close to the edge. I got a Henning x long firing pin which is supposed to help ignite with lighter springs.

Next time out, I had fewer (maybe 1 in 20) FTFire (light strikes) but still a few. No Bueno for competition.

So that's the story. Here's the questions.

I have a match tomorrow. So for now I bumped the hammer spring up to the 15 lb just to gain reliability.

I didn't mention the firing pin spring. This preloads the pin backwards (against the hammer). Here's where I'm confused. TF makes 2 weight springs for this - light and medium. It would seem a stronger spring would make it harder for the pin to move forward. However, they list the light spring for hand loads and/or softer primers and the stiffer spring for factory ammo and/or harder primers. This sounds backwards to me. Can anyone explain?

Also - I don't believe the plunger spring should have any effect on primer strikes - is this correct?

Don't know where else I can go but hammer spring, I already have the longer pin, maybe a stiffer firing pin spring? (But that would seem backwards)

Anyone with any experience tuning a Stock II?

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Hold the hammer back pull the trigger and push on the fp with a punch or something and see if you feel the fp rubbing on the fpb. I always trim my fp spring as it is a little excessive. I only do that because if you look at how a cz is set up it makes you wonder who designed the massive tanfo fp spring.

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I believe you're not doing your gun a favor long term by cutting the spring.

When firing pin is blocked, the FPB spring is compressed. Pulling trigger allows the spring to expand and clear the block. It might be dirt accumulated in FPB slot that holds it in place leading to light strikes. Happened to me once.

I clean my guns occasionally ;)

Edited by arkadi
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I had the issue of the fpb rubbing on the fp with a tanfo that didn't have a reset screw on the trigger which caused the block to lower to much and drag on the fp. This could also be true on the stock 2 which I'm pretty sure some people have reported that the fpb rubs on the fp.

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I did a thorough polishing of the FP channel, FPB hole and lightly touched up the FPB itself. Initial passes with 400 grit on a .22 cal jag and oil turned with a drill moderately. Then 600 and 1000. Finished with ramrodz giant qtips wth polishing compound. Cleaned it all out with brake cleaner and compressed air and then wiped it all down and lightly oiled. Reassembled.

Everything feels much smoother now like the FPB. Someone also suggested FP energy test to check for consistency. So with gun pointed straight up, insert a new, unsharpened pencil (eraser first) in bore. Fire gun and see how high the FP propels the pencil. Repeat. It is consistently throwing the pencil 24" clear of the barrel. A hang up of the FP would manifest as a short throw. Didn't see any after a few dozen tries. Not super scientific but something.

I think I'll go back to the 14 lb hammer spring (from 15) and see if I get consistent ignition now.

Edited by Stevec717
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