Re: 412 tikkia problems
I think I see the pattern you're talking about. But, I'd be curious to see several 4 shot groups.
In any case, it appears to me to be a design flaw with a number of contact points between barrels and the fore-end stock that could cause problems and/or not properly stress releived. You could spend big dollars having the barrels regulated. But, that's money down the drain in my opinion.
If you shoot the 12 Ga, then your POI for the rifle barrel may shift yet again.
I would just have fun with it or sell it. It's never going to be a good long range or accuracy rifle.