Tikka Grouping Issue

[nettereo16]

I picked up a used Tikka 223 and got the barrel cut down to 18" to shoot with my suppressor. It's a 1:8 twist.I mounted a SWFA 3-9 with Sportsmatch using Form's "How to mount to maintain zero guide" - degreased and torqued (40# rail/20# rings)
Trigger set to 2.5#. Factory stock action screws I tried to torque to 65# but this was binding the action. I torqued to 45# which was the max without binding.

I'm waiting for some different ammo to arrive to try it out but the first range session was disappointing.
Hornady Match 75gr BTHP - 3.5" group
Winchester M193 55gr FMJ - 2.5" group

What should I be looking into as a possible issue? My factory stock still has the "nubs" a few inches in front of the action. I plan to fully freefloat before the next range session. What is the deal with the action screws binding the action when torqued? Will installing pillars help with this?

I realize I need to shoot some different ammo before faulting the gun setup but the large group with the nice Hornady Match has me looking to make changes before shooting more ammo.

 

[Legend]

Take a really close look at the new crown on the barrel. Sometimes people are careless with the chop and forget to re-crown or do a poor job.

 

[Antares]

Two thoughts:

1) Free float the barrel (as you suggested).

2) Shoot some groups without the suppressor and see what happens.

 

[mxgsfmdpx]

Take the action and barrel back out of the stock. Get a deep socket that fits in the barrel channel wrapped in sand paper and go to town until you can ensure the barrel is fully free floated at torqued value.
You need to be able to slide a piece of paper folded in half, completely freely to this point...




Don't use 65" lbs with factory plastic trigger guard, go with 55" lbs, degrease them again and apply nail polish or good/known oil based paint pen.

If it still groups poorly, try different ammo. If it still groups poorly, remove the suppressor and shoot without it. If it still groups poorly, you likely have a head space issue (rare, but has been observed in some Tikkas).

 

[mxgsfmdpx]

Also, what do you mean by "action binding"? Are the action screws protruding and interfering with the bolt sliding back and forth (I've seen this on some newer Tikkas) the action screws needed to be filed down a couple thousandths.

 

[Caseknife]

What do you mean by "binding the action", bolt doesn't cycle or something else?

 

[nettereo16]

Also, what do you mean by "action binding"? Are the action screws protruding and interfering with the bolt sliding back and forth (I've seen this on some newer Tikkas) the action screws needed to be filed down a couple thousandths.

Yes - bolt locks up, from what I could tell the action screws are too deep and contact the bolt. It’s an older T3x and I found some olds posts where others had this issue. So file down the bolts a bit ?

 

[mxgsfmdpx]

Yes - bolt locks up, from what I could tell the action screws are too deep and contact the bolt. It’s an older T3x and I found some olds posts where others had this issue. So file down the bolts a bit ?

Yes. The torque you are using is enough for them to protrude into the bolt. File them down a few thous and then use 55" lbs.

 

[bojangles808]

Also, what do you mean by "action binding"? Are the action screws protruding and interfering with the bolt sliding back and forth (I've seen this on some newer Tikkas) the action screws needed to be filed down a couple thousandths.

I have the same issue with the factory bottom metal when trying to go 65 in lbs. was actually thinking of making a thread about it until I saw this bc I wasn't sure what I'm doing wrong. not sure if its the action screws protruding but the bolt doesn't cycle as freely. I back it out till it cycles acceptably, I usually end up somewhere near 45-55 now. this on multiple new t3x lites in OEM /rokstocks. all end up shooting fine

 

[mxgsfmdpx]

I have the same issue with the factory bottom metal when trying to go 65 in lbs. was actually thinking of making a thread about it. not sure if its the action screws protruding but the bolt doesn't cycle as freely. I back it out till it cycles acceptably, I usually end up somewhere near 45-55 now. this on multiple new t3x lites in OEM /rokstocks

Yeah it's a known "thing" in some instances of using high torque values. The screws end up protruding, not enough to really notice by eye, but the bolt will feel "sticky" or "bind" as it's actually slightly rubbing on the action screws.

 

[BAKPAKR]

Did you happen to shoot it before you had the barrel cut? If so, how were your groups?

 

[Dan Carey]

On the accuracy issue, have you shot it with out the suppressor on?

 

[mxgsfmdpx]

OP... One step at time. Guys are reaching out with good suggestions, but don't try to put carts before horses here. Start at the start and go from there with diagnosing. I/we want to know the root cause and if you start messing with shit all at once nobody learns. Appreciate it!

 

[mt terry d]

Any reason not to use a washer instead of filing?

 

[AZ Gator]

The action screws have a tapered shoulder. I’m not saying it wouldn’t work, but it would fit different, stick out more, and be a bit fugly.

 

[Jimbee]

The action screws have a tapered shoulder. I’m not saying it wouldn’t work, but it would fit different, stick out more, and be a bit fugly.

I put little washers between the bottom plastic and the stock and torque action screws to 65in lbs

 

[AZ Gator]

I put little washers between the bottom plastic and the stock and torque action screws to 65in lbs

Wouldn’t that change the spacing of the feed ramp and front of the magazine? Maybe not enough to cause an issue, or maybe it would?

 

[mxgsfmdpx]

Any reason not to use a washer instead of filing?

Good shim washers work and are required with some aftermarket bottom metals, but for this application just filing would be best.

 

[mxgsfmdpx]

Wouldn’t that change the spacing of the feed ramp and front of the magazine? Maybe not enough to cause an issue, or maybe it would?

Yes it does.

 

[Macintosh]

How many rounds in each group?

A washer UNDER the trigger guard will add a small amount of thickness, which will help if the issue is the screws are too long. A soda can cut into a disk with scissors and a hole punch for the center makes a very thin washer that can be stacked to accomplish a very small difference. Or a couple file strokes will do effectively the same thing. I’d let the magazine be my guide—if you have to really push tight to seat the mag, washers may be better. If not, you can cause issues with feeding if you went too far with washers.

Regardless, if you shorten the screws and it still doesnt help it may be that the action bearing surface of the stock is compressed and allowing movement. My feeling is that 45in/lb isnt a problem until you start measuring over time and with rough handling. So I’m doubtful that simply shortening the screws and torquing tighter will help for groups at the range. Worth trying, but if you’re going to tear it down again I’d want to double check crown, action is seated properly, try without suppressor, rings and all connections torqued at the same time. Plus all the caveats about verifying with a known-good shooter, whether thats OP or someone else. If that doesnt do it Id move to the scope next.