Was shooting my reloads for the first time today in my Savage 12fv in 223 (converted to single shot w/ a SSS adapter)

Had horizontal stringing going on as the barrel warmed up, about a 1.5" drift from right to left (in shot order) at 50 yards but once it was warmed up the groups were much smaller (MOA or less, I'm happy ) but were still more wide than vertical (ie, 3 holes right next to each other, each edge touching the ones on left/right)

It may be my prejudice from the Savage Mk II FV rimfire stock but I'm not a fan of the plastic - I think it may flex. In this case, mine is also not exactly perfectly free floated - a single sheet of cheap college notebook paper has a hard time making it all the way down the forearm.

So I'm thinking my wide groups are due to the barrel heating and it not being exactly free floated. Will need to remove action from stock and see if it is possible to hog it out more to really free float it or maybe I should just spend the money at Boyds.

OR

My scope. I've always used an high magnification adjustable objective which is intended to deal with parallax but it also does a great job of keeping the target in clear focus, etc. My new scope is a side-focus, not parallax adjustment. So I guess it could also be my positioning and parallax rearing its head. Will need to stretch it out to 100 yards or more to determine this I think.... although I would expect it to show both horizontal and vertical change and not just horizontal.

Thoughts?