If you took the stock off and reassembled it you could be binding up the magbox, which would affect accuracy. There are youtube videos on this for the Remington 700 so I'd start there before attempting to adjust the trigger. And if you don't have a trigger pull scale or weights then I'd leave the trigger alone.
While Apart, Glass Bed, the Action with about, 1 inch of the Barrels "Shank Portion" All, the way Back to the Tang and, Free Float, the Barrel and be SURE to remove, the Front forend, "Bump" If, any ! Many Forend's have also, "Warped", over the Years !!
Try 130 grain bullets or, better yet, Reload the High BC very Accurate,140 gr. Berger Classic Hunters or 145 gr. ELD-X's.
The Timney Hunter Trigger, is a GREAT Replacement Trigger if, desiring, a better Trig. Pull and EZ to install and the Cost is, reasonable.
Find a Bullet that, "Matches", YOUR Barrel's, Twist rate for,.. BEST, Accuracy !
Not sure but maybe, Hornady offers, the 145 grain ELD-X Bullet, in Factory, Precision Hunter, Loaded Ammo.
As a former Gunsmith,.. I've Accurized, MANY of, these Baby's from, the 1970's thru mid 1990's and, 3 inch group's, ARE, un-acceptable,. IMO
Good Luck