[mcase]

This is the SECOND time?  What did they do the first time?  I am curious about the service they provide.  Until today I had been strongly endorsing Tikka to prospective buyers.    However, at the range today, the most experienced shooter I know  – a former Marine who hunts all over North America and who is meticulous about all aspect of shooting was trashing Tikka.  I own two and both are superb so I was intrigued.  Evidently  his first and only Tikka was a total bum shooter.  He tried to get his hopelessly inaccurate rifle corrected . The response he got from the dealer amounted to “drop dead”.  This alarmed me.  I'm trying to get a sense of what kind of company I've been recommending to people.  Obviously they failed to correct your issue.  It sounds as if the head spacing is wrong.    Did you send it back again already?  If you still have it try a “go” head spacing gauge on it – maybe someone  you know has a one (they are about twenty bucks).  The reason I suggest this is that it takes the debate out of it.  If the “go” gauge won't go in and allow the chamber to close the head space is too tight – Period end of discussion.  if this is case either barrel is not chambered correctly or is too deeply engaged in the receiver either way its the manufacturer's problem – or should be.    Good Luck!

[mcase]

Hi Craig
I would hesitate to switch barrels because there are so many other possible causes for variable accuracy.  Also if the rifle shoots 150 grain well I doubt its the barrel.  The Tikka .308 is a 1 in 11 twist which can handle loads a lot heavier than 155 grain, so something is not right.  I shoot 165 grains with my t3 lite and get moa groups which is all I ever hope for or need in a hunting rifle.  Mine would NOT shoot certain powders though.  It would give me poor groups using Hodgdon Bl-c2, but fine groups with IMR 4320.    So here are some things to consider instead of changing instead of the barrel  1. the type of powder and the amount of powder  – there's a lot to play with here  2. Your case shoulders might be shy  – have you checked them with a case length gauge?  – believe me this can make a difference  3. Have you considered what your jump rate is?  If your bullets are sitting too far from the rifling things will never be very accurate.  I always make a dummy round and set the bullet long without a crimp and put it into the actual chamber of the rifle I'm loading for to find out just how far I have to set the bullet to just get to the rifling  – There are plenty of articles on how to do this. .  Some precision shooters have their bullet actually engage the rifling and have zero jump.  For a hunter not a good idea, but you want  that bullet close even touching is ok.      These are just some of the variables to consider before even thinking of re-barreling.    Again if it shoots 155 well I doubt its the barrel.  If it were it would not shoot anything well.  I hope this helps

[mcase]

Thanks Mallard,
That's a thought.  I think the debris which is light and dusty is probably cinder from not fully burned powder.  So I'll try heating up the load and try another powder as well.