I've upgraded a couple of tikka rifles. To get that original rifle shooting it's best, get a lighter trigger spring, SS recoil lug and a better stock and have it bedded. The factory trigger is great, but can only be adjusted down so far. The spring will get you down into the 1-2lb area, perfect. The recoil lug is a weak link, a SS lug is cheap. Then if you want to go deep order a nice McMillan or Manners for it. I believe Stocky's also has a couple carbon fiber options that are real nice and still accept the factory mag setup. I wouldn't worry about the trigger guard assy, it may be plastic but mine have had their share of hard knocks and weren't phased a bit.