Tuning Stock II Ex

[Stevec717]

(Reposted from the shop - probably should have been over here)

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?

Update - shot a match today 150 rds - no misfires. (W/15 lb hammer spring). I'd like to go back to 14 if I can retain reliability.

[emjei]

Subscribed since they are good questions

Mj

[Honeybooboo]

This is what scares me about the stock 2 and makes me wonder if I should even mess with my brand new once since I do t reload.

[johnbu]

There are true experts here (I'm not!) But I've done 5 tanfos and have a few generic things that will possibly help.

1) double check the primers are fully seated. I just reseated 3000 rounds of finished ammo on a single station press because I failed to get right.

2) put a new pencil in the barrel eraser first and launch it straight up 10-20 times next to a wall (in da and then again in sa) and mark how high they go. That's your baseline. After "doing things", check to see if it helped. You may also find the firing pin safety is rubbing the firing pin occasionally. If one or two launch significantly shorter, that's a sign!

3) Polish the inside of the holes for the hammer, firing pin and especially the firing pin safety. On several of mine the holes were rough as heck.

4) polish the moving bits. Each component of the hammer, strut, pins, firing pin and the firing pin block.

I did the above and gained 8-10" of pencil launch height polishing. In fact, the 13# wolfe hammer spring w EG light firing pin spring along with the usual parts, launches the pencil to the same height as the gun did stock.

Edited March 6, 2016 by johnbu

[Stevec717]

There are true experts here (I'm not!) But I've done 5 tanfos and have a few generic things that will possibly help.

1) double check the primers are fully seated. I just reseated 3000 rounds of finished ammo on a single station press because I failed to get right.

2) put a new pencil in the barrel eraser first and launch it straight up 10-20 times next to a wall (in da and then again in sa) and mark how high they go. That's your baseline. After "doing things", check to see if it helped. You may also find the firing pin safety is rubbing the firing pin occasionally. If one or two launch significantly shorter, that's a sign!

3) Polish the inside of the holes for the hammer, firing pin and especially the firing pin safety. On several of mine the holes were rough as heck.

4) polish the moving bits. Each component of the hammer, strut, pins, firing pin and the firing pin block.

I did the above and gained 8-10" of pencil launch height polishing. In fact, the 13# wolfe hammer spring w EG light firing pin spring along with the usual parts, launches the pencil to the same height as the gun did stock.[/y quote]

This is some good advice I will try. I'm wondering now if I really "had it right" and just got a high primer or a little hang up as you describe. Although not scientific, when I examined my spent shells today they are sharply impacted (not shallow strikes). So I could be having intermittent hang ups or just the odd high primer. I am going to polish the firing pin channel and FPS channel. I'm thinking a stick just smaller than the hole with some polish on it turned in a drill. I may also have long wood stick q-tips for cleaning that I could load up the cotton with polishing compound. I'll figure something out. I really should be able to go down to the 14 or even 13 lbs hammer spring with XL firing pin and still have reliability.

[Honeybooboo]

There is a company called ram rodz I believe that makes basically giant q tips for barrel cleaning. One of the .22 caliber ones might be good for polishing the firing pin channel.

[bthoefer]

There is a company called ram rodz I believe that makes basically giant q tips for barrel cleaning. One of the .22 caliber ones might be good for polishing the firing pin channel.

I've used a 22 caliber chamber hone to polish the firing pin channel in my CZs, it would probably work well with the Tanfo also.

[johnbu]

There is a company called ram rodz I believe that makes basically giant q tips for barrel cleaning. One of the .22 caliber ones might be good for polishing the firing pin channel.

I've used a 22 caliber chamber hone to polish the firing pin channel in my CZs, it would probably work well with the Tanfo also.

To polish the firingpin channel FIRST!, remove the extractor and spring. Part of it extends into the channel. I put polishing compound on a barrel cleaning patch and use the patch holder chucked up in a power drill. If it's real rough, you can chuck up some 600, 800 or so grit sandpaper first. But don't remove much or other issues will be created.

I prefer a drill as it's slower and more controllable. Works on the firing pin safety hole too.

[Stevec717]

There is a company called ram rodz I believe that makes basically giant q tips for barrel cleaning. One of the .22 caliber ones might be good for polishing the firing pin channel.

I've used a 22 caliber chamber hone to polish the firing pin channel in my CZs, it would probably work well with the Tanfo also.

To polish the firingpin channel FIRST!, remove the extractor and spring. Part of it extends into the channel. I put polishing compound on a barrel cleaning patch and use the patch holder chucked up in a power drill. If it's real rough, you can chuck up some 600, 800 or so grit sandpaper first. But don't remove much or other issues will be created.

I prefer a drill as it's slower and more controllable. Works on the firing pin safety hole too.

[Stevec717]

There is a company called ram rodz I believe that makes basically giant q tips for barrel cleaning. One of the .22 caliber ones might be good for polishing the firing pin channel.

I've used a 22 caliber chamber hone to polish the firing pin channel in my CZs, it would probably work well with the Tanfo also.

To polish the firingpin channel FIRST!, remove the extractor and spring. Part of it extends into the channel. I put polishing compound on a barrel cleaning patch and use the patch holder chucked up in a power drill. If it's real rough, you can chuck up some 600, 800 or so grit sandpaper first. But don't remove much or other issues will be created.

I prefer a drill as it's slower and more controllable. Works on the firing pin safety hole too.

Yes, I have the whole ramrodz assortment ( couldn't think of the name). Good advice about the extractor I might not have thought to do that.

Although the action was nicely smoothed on this gun, other machining not so much. I polished the mag release channel as it was very rough - much better after. So I wouldn't be surprised if the FP channel is rough too.

[johnbu]

Yeah.... I learned that the patch holder could catch on the extractor part in the channel and break the holder. Oops!

[waktasz]

Take the firing pin safety out and shoot it for a while. If it works 100% without it, you have an issue with the timing of the FPS.

[cakedog02]

I too have wondered why a "light" firing pin spring is not recommended for factory Ammo. It seems backwards to me too. Would love to here the reasoning behind it.

[johnbu]

I too have wondered why a "light" firing pin spring is not recommended for factory Ammo. It seems backwards to me too. Would love to here the reasoning behind it.

Factory hammer spring is (iirc) 16#. That spring, with empty chamber, can drive the firing pin so far forward it sticks if the FP "light" spring is used. Like a full inch forward and it takes a good tap to knock it loose.