SOLVED: Rear Tikka T3x Action Screw feels "Mushy"

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Canuck65

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I'll try to explain this as best I can. When I tighten the action screws on my T3x, the front one snugs up and feels "snug" - you can definitely feel that it's tight and everything is clamped together as it should be.

When I tighten the rear screw though, it feels like it wants to keep going. I actually collapsed the encapsulated metal washer on the trigger guard before I hit torque spec, and the screw pushed right through it. I replaced it with an aluminum bottom metal, and it's better, but it still feels "mushy" like the screw wants to keep going - like everything's flexing a bit.

I 2-point bedded the action (the problem existed before I did the bedding), but I did not bed the bottom metal - problem persists. I suspect it's the bottom metal that's flexing.

Any advice before I start messing with bedding the trigger guard or putting shims in? I've heard this can happen with laminate stocks, but I've never experienced it personally before.

Tikka T3x stainless/laminate in 30-06. Atlasworx bottom metal sits flush at the front, but a little below the wood at the back. Torqued to 35 in lbs

Thanks in advance.
 
One small issue is that the action screws are not perpendicular to the floor plate. Can't remember if Atlasworx has a 90 deg countersink or just flat. Would be better to have a 90 deg counter sunk but also perpendicular to the action. Pillars in a wooden stock would be better, I would make sure the action screw hole in the stock is around 8mm diameter, not smaller. Screws must stay away from touching the stock. Pillars should be inline with the bottom metal, meaning the floorplate should sit flat on the pillar, not on edge. Bedding and pillars would be the best.
We never really noticed accuracy differences if action screw torque was changed from say 5NM to 6 NM. Even just hand tightening was OK which could have been closer to 4NM on occasions. Important is a good action bedding. My experience is based on carbon stocks, not wood.
edi
 
Thanks for the replies. I had a good look at things again, and I don't believe the stock is compressing (or at least I see no evidence of that.

The action is bedded at the recoil lug and rear tang areas. Everything looks great there, and there's absolutely no movement of the action in the stock.

Interestingly, the bottom metal is not perfectly aligned with the action screws (thanks EJG for this tip). I thought this was an Atlasworx problem, but the old plastic bottom metal doesn't line up exactly either, which would explain why the screw deformed the rear internal metal washer.

I'm not 100% sold on the idea of pillar bedding a cheapo Tikka - seems like more work than it's worth. I use this rifle when I'm hunting in the rain or bush-whacking. It looks like the bottom inletting wasn't done very well on this laminate stock - I'll relieve a tiny bit of wood to line everything up properly, then use a bit of Devcon to flush everything up again - I'm sure this will do the trick.

Thanks again for the advice.
 
Bed the bottom metal to the stock with no stress... no screws... I think that should cure the "mushy".
 
Posting the solution here in case anyone else experiences this issue:

The screws were perfectly perpendicular, so that wasn't the issue. The bevels on the Atlasworx bottom metal were flawless, so that wasn't the issue

The issue was the inetting. I guess I got a Friday-afternoon inletting job. What I did was tighten my screws up, then measured the rear of the bottom metal with a depth gauge. I kept the front screw tight and slowly backed off the rear screw until there was no pressure on it.

Low and behold - a 4/100ths difference.

I tightened them again, and this time watched the bottom metal through a magnifying glass as I backed off the rear screw. I could see the stress coming off the trigger guard clear as day. I missed this the first time because I guess my near vision isn't what it used to be (hahaha).

Rather than go through the bother of scraping the hump out of the inletting, I just carefully cut and added a 4/100ths shim held down with a very tiny dab of Devcon at the back, then tightened everything down again with a coating of release agent.

Let it cure, and everything is absolutely perfect now. A solid "feel" when I tighten that screw, and absolutely no flex at all.

Thanks again everyone for your input.
 
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