Tikka & sako are seperate companies but are both owned by the same company,Beretta I think,both make their own firearms seperately,however I believe barrels for both are made by sako.

Sako is definately the better rifle as reflected in the price but tikka is a fine accurate rifle as well.

Having used both rifles,Tikka actions are different than sako & I think the fittings & finish of the tikka is not up to the sako standard,however the tikkas are a fine rifle for the price.

Dont know about an accuracy guarrantee & wouldn;t have much faith in any & accuracy will vary between rifles & calibres but both sako & tikka are accurate rifles & sako actions are often saught after by target shooters.