I have seen a little misinformation on this one – so here it is. No. You don’t need to pull a Tikka TAC A1 apart to adjust the trigger. It is a little fiddly, and, you need an Allen key that isn’t supplied with the rifle. I think that might be what is tripping people over.
Take the magazine out, and there is a hole in the rear of the mag-well where the Allen key can fit into. It’s a bit fiddly, but it’s doable. God damn that trigger does light!