Tikka Zero Acting Weird

[Geysermutt]

So I’ve been working to dial in my new rifle setup and I’ve run into an interesting situation.
The setup is a tikka lite stainless 6.5 cm in a factory stock that is bored out to free float the barrel. It has a mavin rs 1.2 with zeiss ultralight scope rings on a picatinny rail.

What I’m running into is that after I’ve zeroed the gun I can tap(almost slam) the forend into the front sand bag which causes the next round to hit 1.5” right, and sometimes 1.5” low. After 1 to 2 more shots the rounds will work their way back to zero. I can repeat this every time.
After I found this out I pulled the scope off and re-cleaned all the threads. I then degreased everything and re-mounted the base to rifle(45in-lbs), the rings to base(65in-lbs), the rings to scope(25in-lbs), and the action screws (65in-lbs). I even played with higher and lower torque numbers for the actions screws and was still having this repeatable issue.

My gut tells me it’s a bedding issue but I was wondering if anyone has had something like this before, and what the solution was.

 

[The Harbor Master]

What picatinny scope rail do you have? 45 in lbs sounds like a lot.

 

[Geysermutt]

What picatinny scope rail do you have? 45 in lbs sounds like a lot.

It’s a leopold rail. I had it at 25 in-lb I think and wanted to eliminate that variable so I incrementally went up to about 45 in-lb

 

[JohnJohnson]

Sounds to me like a bedding issue. I'm a Tikka novice but it sounds like an issue guys run into with unbedded chassis on PRS guns.

 

[Halligan]

Given the due diligence you did for the scope, try pulling out the barreled action and reassemble with the correct torque and loc tite/paint penning (if you haven’t done so already). There is a possibility that the lug isn’t seated in the stock correctly

 

[Geysermutt]

Given the due diligence you did for the scope, try pulling out the barreled action and reassemble with the correct torque and loc tite/paint penning (if you haven’t done so already). There is a possibility that the lug isn’t seated in the stock correctly

I guess I didn’t mention that. I’ve also pulled the action a couple times to double check the lug was seated and torqued correctly. Also all the screwed mentioned above are loctited

 

[Antares]

Mount a known, working scope and see what happens. You’ll know if it’s the scope or something else after that.

 

[Geysermutt]

Mount a known, working scope and see what happens. You’ll know if it’s the scope or something else after that.

Good in theory. when I bought this scope I figured it was a known, working scope. I’d hate to have to spend another $700-$1200 on another scope that I’m not sure if it’s a working scope as well.

 

[Antares]

Apologies if I was unclear.

What I meant was, do you or anyone you know have a different scope (that is known to currently be functioning correctly) that you can temporarily mount on the rifle to help you isolate where the problem is? A “control” in the experiment, if you will.

I was not suggesting that you buy a different scope

 

[4th_point]

What I’m running into is that after I’ve zeroed the gun I can tap(almost slam) the forend into the front sand bag which causes the next round to hit 1.5” right, and sometimes 1.5” low. After 1 to 2 more shots the rounds will work their way back to zero. I can repeat this every time.

At first glance, a weak erector spring could be the cause. It seems unlikely, but do you have the elevation or windage anywhere near max travel?

I would also suggest that you run the elevation and windage back and forth a bunch. There might be an interface issue between the turret mechanism and erector tube

Last, when you re-check this, I would zero on one target. If possible, shoot 10-shots on that target so we can see the distribution. Then, drop the fore end on the rest, but shoot an adjacent target. This target needs to be in close proximity to the first target so that the shooter position and aim are similar.

Keep track of the shots and sequence. We need to see how well the rifle is zeroed on that 1st target. And we need to see where POI is after the drop, on another target.

FYI - there was/is a similar observation and thread at a different forum, but with heavier comp rifles.

Good luck. PM if you want.

 

[Macintosh]

I guess I didn’t mention that. I’ve also pulled the action a couple times to double check the lug was seated and torqued correctly. Also all the screwed mentioned above are loctited

My first reaction was action screws. It sounds like the action could be moving slightly in the stock, and then recoil re-seating it. How tight did you torque the action screws? When you opened the barrel channel is it possible you inadvertantly opened anything back where the action sits?

Is your initial zero a 4-round zero as shown? If you havent already I might shoot at least one larger group (10rounds +) to determine the cone of fire of the gun so you have a good sense of how far outside the cone those shots are. It seems repeatable so probably this isnt it, but its possible from the photos they are actually still inside the cof. Even if this isnt the issue here it may help in the future.

 

[mxgsfmdpx]

So you take a piece of paper folded in half and it doesn’t have ANY resistance until it hits here correct?



And you’ve ensured that your action is actually seated properly on the lug? I’ve seen dozens of photos of Tikkas on here with them not seated when folks swore that they were.

Is your pic rail bonded to the action or using pins? Or does it rely on the little baby screws on top of the action to hold it only?

If you don’t mind, send some photos of your setup please.

 

[TaperPin]

You can check if it’s a bedding issue by inserting thin cardboard (cereal box) or layers of regular paper shims between the sides of receiver and stock.

I put a long, 1/2” wide cardboard shim all the way under and around from side to side.

 

[waspocrew]

So you take a piece of paper folded in half and it doesn’t have ANY resistance until it hits here correct?

View attachment 872196

And you’ve ensured that your action is actually seated properly on the lug? I’ve seen dozens of photos of Tikkas on here with them not seated when folks swore that they were.

Is your pic rail bonded to the action or using pins? Or does it rely on the little baby screws on top of the action to hold it only?

If you don’t mind, send some photos of your setup please.

My first thought was the action wasn't actually seated on the lug.

 

[Geysermutt]

Apologies if I was unclear.

What I meant was, do you or anyone you know have a different scope (that is known to currently be functioning correctly) that you can temporarily mount on the rifle to help you isolate where the problem is? A “control” in the experiment, if you will.

I was not suggesting that you buy a different scope

That makes more sense, I’ll ask around.

At first glance, a weak erector spring could be the cause. It seems unlikely, but do you have the elevation or windage anywhere near max travel?

I would also suggest that you run the elevation and windage back and forth a bunch. There might be an interface issue between the turret mechanism and erector tube

Last, when you re-check this, I would zero on one target. If possible, shoot 10-shots on that target so we can see the distribution. Then, drop the fore end on the rest, but shoot an adjacent target. This target needs to be in close proximity to the first target so that the shooter position and aim are similar.

Keep track of the shots and sequence. We need to see how well the rifle is zeroed on that 1st target. And we need to see where POI is after the drop, on another target.

FYI - there was/is a similar observation and thread at a different forum, but with heavier comp rifles.

Good luck. PM if you want.

When I get out to the range I’ll test this out and get some photos. Currently I’m right about middle for windage and elevation adjustments in the turrets. The groups are around 1” for this gun load combo, with no horizontal or vertical stringing.

My first reaction was action screws. It sounds like the action could be moving slightly in the stock, and then recoil re-seating it. How tight did you torque the action screws? When you opened the barrel channel is it possible you inadvertantly opened anything back where the action sits?

Is your initial zero a 4-round zero as shown? If you havent already I might shoot at least one larger group (10rounds +) to determine the cone of fire of the gun so you have a good sense of how far outside the cone those shots are. It seems repeatable so probably this isnt it, but its possible from the photos they are actually still inside the cof. Even if this isnt the issue here it may help in the future.

Action screws were my though too. I noticed it when they were torqued to 65in-lb. Since then I’ve tested it between 50 and 70+ in-lb. It was slightly less worse at 70in-lb which is why I’m leaning towards a bedding issue. I’ve also shot many 10 round groups. Right around 1” for this gun and load.

So you take a piece of paper folded in half and it doesn’t have ANY resistance until it hits here correct?

View attachment 872196

And you’ve ensured that your action is actually seated properly on the lug? I’ve seen dozens of photos of Tikkas on here with them not seated when folks swore that they were.

Is your pic rail bonded to the action or using pins? Or does it rely on the little baby screws on top of the action to hold it only?

If you don’t mind, send some photos of your setup please.

Here are some photos. I’m pretty confident the lug is seated, but I am human. Barrel is fully floated to the action. Pic rail is not bonded to the action, but torqued 4 screws to 45in-lbs(I’m planning on switching to rings going directly on the tikka rail).

You can check if it’s a bedding issue by inserting thin cardboard (cereal box) or layers of regular paper shims between the sides of receiver and stock.

I put a long, 1/2” wide cardboard shim all the way under and around from side to side.

are you talking about putting these paper shims around the front portion of the action?

 

[Speaks]

Torque for action screws in the factory stock is 45.

I would ditch the rail and try the UM rings.

 

[TaperPin]

are you talking about putting these paper shims around the front portion of the action?

They need to be front and rear of action directly against the receiver screws whichever way makes sense - punch holes for the action screws if you like. If bedding is loose you’ll see a difference right away.

 

[Wacko]

IMHO....I think your theory on bedding is correct. In Form's podcasts he mentions that occasionally there will be a shift in zero with a tikka...and he spot beds the lug and rear tang...and it goes away. It sounds like your assembly is good... I would make sure you thread lock and torque all your screws...also if not going directly to the rail with rings...bond the scope rail to the action with loctite (pretty sure it is 380?)...

 

[mxgsfmdpx]

That makes more sense, I’ll ask around.


When I get out to the range I’ll test this out and get some photos. Currently I’m right about middle for windage and elevation adjustments in the turrets. The groups are around 1” for this gun load combo, with no horizontal or vertical stringing.


Action screws were my though too. I noticed it when they were torqued to 65in-lb. Since then I’ve tested it between 50 and 70+ in-lb. It was slightly less worse at 70in-lb which is why I’m leaning towards a bedding issue. I’ve also shot many 10 round groups. Right around 1” for this gun and load.


Here are some photos. I’m pretty confident the lug is seated, but I am human. Barrel is fully floated to the action. Pic rail is not bonded to the action, but torqued 4 screws to 45in-lbs(I’m planning on switching to rings going directly on the tikka rail).

are you talking about putting these paper shims around the front portion of the action?

This looks seated and fully free floated.

For factory plastic stock and factory bottom plastic, 55” lbs works great for action screws. Anything above 60ish I’ve seen instances of hairline cracks in the plastic near the screw holes (very hard to see with naked eye sometimes).

I’d take it apart and spot bed the lug area and screw it back together with paint penned screws at 55” lbs and see if it resolves the issue.

I’d highly recommend ditching the rail unless you bond it… Go with direct dovetail mounts with pins (UM or Sportsmatch).

 

[4th_point]

If this was a different factory action and stock, I'd suspect the "bedding" too. Tikkas are so dang consistent in that regard, that I still suspect a scope issue as being most likely and not mounting or stock.

However, here some things for you to consider on the other possibilities:

1. Tikkas generally do not need any bedding or stock work, but there could be a tolerance mismatch - I would use a Sharpie and mark the contact points on the action then carefully install the barreled action and torque it down. Then remove the barreled action and make note of any marker that was removed. Redo the marker, install, and then drop the works on the buttpad and make note of any differences. This doesn't always work for detecting relative motion, but its easy and FREE! And you might see some uneven contact.
2. Same deal with the rail, but look for any indications of relative motion between the rail and the action. You've already shot the works, so any motion at the interface should show up on the action or rail finish. Tikkas are made with tight processes, and an out of spec action applies more to some other brands, but it's possible the rail is the root cause. Some Leupo rails have defects in the 1913 portion - some you can see with unaided eyeball! The bottom of the rail is relatively easy produce, but it would be worthwhile to inspect for contact wear.
3. Also check for wear marks on the scope rings where they contact the scope tube - you'd be surprised how much the finish will wear, while the scope has no marks at all.
4. Check the luggette for marks - this one is self explanatory. I wasn't concerned with your installation, but while you're at it...

Last, I've had five Tikkas and set up more for others. On all, I just used the supplied Torx key and snug them up. I have a calibrated torque wrench, but I don't carry it in my pack. I do carry a few Torx and Allen keys though, and am not a big fan of needing a specific torque value on the action screws - blame those damn 77/Hawkeyes!

Good luck