My 308 CTR likes the 165gr SST Superformance a little better than the 150's…give those a try if haven't already.  I've never had a group larger than 1″ measured from outside to outside (without shooter error) @ 100yrds.

The Sierra Match King 168 actually shot the worst in my rifle out of the 2 boxes I've fired if you averaged the group size…Some groups would be 1 hole, and then another group would make you think you had put different ammo in the gun. Though it produced some of the tightest groups, it was not consistent enough to continue buying it.

The Nosler 165 Accubond is my go to “factory” hunting ammo…its given me the best results at the range and in the field.  Its worth a try of you are looking go for something to switch it up.
The best 100yrd factory ammo I have tried to date is the Nosler 150gr Match, but it did not do as well at 200+ yrds…. The Hornady 150gr match was a close second.

There is no substitute for hand loading in these rifles…
I just worked up and tested some 178gr amax loads for my CTR this past weekend.
It likes 45.1gr of Varget, .03 off the lands = COAL of 2.87″
Groups @ 100 where 1 hole or small clovers all touching.
Groups @ 200 where a consistent .5-.75″
Going to play around with the powder charge a little more at extended ranges to see what happens, but primers are starting to flatten a bit so its pretty much a max load already.

Hi a guy I shoot with uses sako game heads , I've forgoten the exact Gr but it's around 165 , last weekend he got 3 shots in the same hole

Nice Shooting!

I have never even thought of trying these, till I saw the group you shoot.
A buddy of mine shoots a winchester 70 and he loves this bullet.

I need to pick up a box!

(Also, action is torqued to 51 in/lbs )

That's too much.

Way too much! 35-45 at most I think, are you using a good torque wrench?

All 5 of my rifles are torqued to 45in/lbs…just a number I've picked after seeing all the chatter on torque specs.  They all shoot great and I honestly have not noticed a difference in the way they shoot if I went 5in/lbs in either direction.

51 sounds like a lot but if it doesn't effect the accuracy or damage the stock then I cant't see way it won't work. Beretta actually suggest 51-53in/lbs if my memory is correct, I think someone here actually contacted them to confirm and posted the information.

I think 40in/lbs for a wood stock with no pillar bedding seems to be an industry norm.
Ultralite stocks with pillar or aluminum bedding block up to 55in/lbs
I know Browning as suggested 65in/lbs on some of their stocks…that seems high but who knows…

Its pretty crazy that the numbers are all over the place from different manufacturers but with all the different materials these days I guess its reasonable. 

How does your recoil lug look?

…And did you hear a…crack…from the bottom “metal” when you cranked it that tight?

I've said it before, and I'll say it again:

35 inch pounds on wood Hunter and Lam stocks
45 inch pounds on factory synthetic stocks

Snug the front screw first, then the rear.
Then torque the front screw, then torque the rear.
Then re-torque them.

Break it down fully and re-torque to 45in/lbs…Just check it after a day of shooting and see if its backed off at all but I honestly don't think you will have an issue.

I've had 2 of my guns torqued up to 55in/lbs a few times when testing to see if the settings actually made a difference in accuracy and I noticed no different between 35-55in/lbs with either setting if both screws were equally torqued the same.

If youkonal says something, you can pretty much take it to the bank. He knows Tikkas and you can read the articles to feel comfortable in his advice.  Get an appropriate torque wrench, you will use it for everything including scope mounts.  Good luck
-Eric