Is my crown letting my down?

[Jaco_dK]

Greetings,

I just want to get some opinions on if my accuracy problems are due to my barrel's crown.

I'm struggling to get sub-MOA groups with my Tikka T3x, chambered in 260 Remington, since it has been threaded for my new suppressor. Four shots would group superbly and one would mess everything up. Yesterday I've noticed a notch where the threads "dropped" some of the crown.

- I firstly cleaned the action and barrel until I got a white cotton cloth.
- I've also ensured that everything is torqued to spec (for my scope and MDT XRS chassis).
- I've loaded different loads (from very moderate to right on the brink).
- And I've tried different seating depths as well. (My rifle's lands are smack-bang on SAAMI - @2.800" - so I usually load my rounds at 2.780", which she liked until I got the can.)

The only thing that is left is the crown?

Please see the pics attached for reference.

If it's the crown, will I have to chop the barrel down and recrown? (With a different gunsmith this time.)

Thanks in advance,
J

 

[2muchcowbell]

Morning J,

I don't think the crown is the issue. During their barrel length tests, they sawed barrels down to 16-17" from 20 or so inches, without shocking deterioration in accuracy. Here's the article I'm referencing:

Do rifle crowns matter? Does a crown affect accuracy? I find out with the help of my grinder…

Do rifle crowns matter? Does a crown affect accuracy? I think most of use would say yes. It seems intuitive that the crown, the last part of the rifle that touches the bullet before it leaves the…

rifleshooter.com

 

[TRPrecision]

That starter thread should have been chamfered down, not sticking up above the crown. It is a very simple fix, but I don't really think that is causing your problem. The threads themselves however look pretty horrible as well as the shoulder. These threads were not properly formed and could possibly be unsafe, crooked etc. I would find another smith to cut, rethread and crown that barrel.

 

[srt-4_uk]

Those threads look like shit.

 

[iashooter]

If the threads are clean and that's truly what they look like, I'd cut it and re-thread.

 

[Jaco_dK]

Morning J,

I don't think the crown is the issue. During their barrel length tests, they sawed barrels down to 16-17" from 20 or so inches, without shocking deterioration in accuracy. Here's the article I'm referencing:

Do rifle crowns matter? Does a crown affect accuracy? I find out with the help of my grinder…

Do rifle crowns matter? Does a crown affect accuracy? I think most of use would say yes. It seems intuitive that the crown, the last part of the rifle that touches the bullet before it leaves the…

rifleshooter.com

Thanks for the quick reply. And what an interesting read. I would never have thought that a stuffed up crow would still push those holes.

 

[Jaco_dK]

That starter thread should have been chamfered down, not sticking up above the crown. It is a very simple fix, but I don't really think that is causing your problem. The threads themselves however look pretty horrible as well as the shoulder. These threads were not properly formed and could possibly be unsafe, crooked etc. I would find another smith to cut, rethread and crown that barrel.

Thanks for the advise. My first thought was that I'll have to cut and rethread (when I saw the Picasso at the end of my barrel).

 

[VargmatII]

The guy who cut that thread should be ashamed of himself. It looks horrible!

You might have to adjust your load recepies if you handload or try out different factory ammo if you cut the barrel down.

 

[Supersubes]

Dont take it back to the same gunsmith.

 

[TRPrecision]

If you were local I would offer to fix it for you for free. Your profile says you are in Namibia, that may be a bit too far to travel. LOL

 

[ShtrRdy]

Is the shot that's further out always the same shot in the sequence? If so, which shot is it?

I don't know if this is related but I recently had a barrel replaced on a 22-250. I used a 55 gr bullet with the original barrel with great results. The new barrel would put two bullets close together and 1 bullet further out. The outlying hole could be from the 1st, 2nd, or 3rd shot. I tried a bunch of things including having the gunsmith look it over and pre-cut the crown. What seems to be making a difference is to use a different weight bullet.

 

[Steel head]

Ouch!

Looks like a beaver chewed on the threads

 

[jakelly]

Beware the local gunsmith...

Tikkas usually have unusually tight barrels. I’d be highly concerned if this guy removed the barrel. I doubt the crown is the issue.

Couple questions:
Are you shooting these groups with the suppressor?
If so, have you tried shooting w/o the suppressor?
I would ask the “gunsmith” if he tried to remove the barrel.

If he did, my guess is it’s an issue on the other end of the barrel. Had a “local guy” twist a friend’s action years ago, had run a bar through the ports to remove an action. Incredible.

 

[1moaoff]

Threads look like ass... crown not likely your problem..

1. Can you shoot better MOA repeatedly?
2. Has it ever shot sub moa?
3. Have you tried factory ammo?

Let's start at the beginning.

 

[Im2bent]

Did he cut those threads with a hand file?

 

[Supersubes]

Did he cut those threads with a hand file?

Theyre too shitty for that. Im thinking he used a hammer and chisel.

 

[Guthwine]

Theyre too shitty for that. Im thinking he used a hammer and chisel.

Or a spoon.

 

[BuLLet]

or his teeth

 

[Jaco_dK]

If the threads are clean and that's truly what they look like, I'd cut it and re-thread.

Thanks. Think that is what I'm going to do.

 

[Jaco_dK]

The guy who cut that thread should be ashamed of himself. It looks horrible!

You might have to adjust your load recepies if you handload or try out different factory ammo if you cut the barrel down.

I did, briefly, consider taking it back. But I'm afraid I'd get more of the same.
I'll definitely rework my loads when she's repaired.

 

[Jaco_dK]

If you were local I would offer to fix it for you for free. Your profile says you are in Namibia, that may be a bit too far to travel. LOL

Thanks. It's a very kind offer. But it is a tad far

 

[Jaco_dK]

Is the shot that's further out always the same shot in the sequence? If so, which shot is it?

I don't know if this is related but I recently had a barrel replaced on a 22-250. I used a 55 gr bullet with the original barrel with great results. The new barrel would put two bullets close together and 1 bullet further out. The outlying hole could be from the 1st, 2nd, or 3rd shot. I tried a bunch of things including having the gunsmith look it over and pre-cut the crown. What seems to be making a difference is to use a different weight bullet.

It's usually the 2nd or 3rd shot.
I'll have to work on new loads anyway, so I'll try different weights.
Thanks.

 

[Jaco_dK]

Beware the local gunsmith...

Tikkas usually have unusually tight barrels. I’d be highly concerned if this guy removed the barrel. I doubt the crown is the issue.

Couple questions:
Are you shooting these groups with the suppressor?
If so, have you tried shooting w/o the suppressor?
I would ask the “gunsmith” if he tried to remove the barrel.

If he did, my guess is it’s an issue on the other end of the barrel. Had a “local guy” twist a friend’s action years ago, had run a bar through the ports to remove an action. Incredible.

Jip, it's with the suppressor. (Didn't even think of removing it, thanks.)

I'll ask him.
He did work on one of my other rifles, without any issues. So I didn't think there would be any problems. (No better sight than hind sight ...)

 

[Jaco_dK]

Threads look like ass... crown not likely your problem..

1. Can you shoot better MOA repeatedly?
2. Has it ever shot sub moa?
3. Have you tried factory ammo?

Let's start at the beginning.

I'm no marksman but I can comfortably shoot 0,9" at 100m (110 yards).
I got my groups down to 0,73" with the rifle is question.
And we, unfortunately, don't get factory 260 ammo here.

I'll ask a friend (who shoot a lot better than me) to take some shots (driver error is always an option).

 

[jakelly]

Jip, it's with the suppressor. (Didn't even think of removing it, thanks.)

I'll ask him.
He did work on one of my other rifles, without any issues. So I didn't think there would be any problems. (No better sight than hind sight ...)

Ok, well if that suppressor isn't straight (concentric with the bore) it will effect the groups. Even if you don't have a baffle strike you will create pneumatic pressure imbalances within the suppressor. Looking at the machine work on those threads, I have a hard time believing he got them concentric to the bore.