IMO,.. several things, "may" be going on,.. Like stated above, 1) try a different Powder/ Bullet combo. 2) If, the HS stock has an Aluminum bedding Accublock in it, it is already semi-pillar bedded but, might NOT, fit your action perfectly level or possibly, side to side "binding" and you may want to buy some of Ernie the Gunsmith's "pillar rings" and re-bed it with good clearance but supported by the "Rings",.. go online to see his "process" I just bedded my HS stock a .22-250 Rem Sporter and it shoot's SUB 1/2 MOA. Also check to make sure the Bbl. Shank area, is bedded about, 1.5 inches or so, to support that heavy Bbl. and check forearm area "free float" for, bbl "clearance" 3) Try cleaning the bore with some Barnes CR-10 to get the copper out, THEN put a tight fitting Patch, over, a Bronze brush and SLATHER ON some JB's Bore Cleaner to "Polish" your Throat/ Rifling land area, 20-25 strokes, then clean to remove the JB's (my Factory Tikka, T3, SS Lite, .270 WSM, shoots 1/2 -3/4 MOA, I used this cleaning process when rifle was New. Take it one step at, a time and Good Luck ! I was a Gunsmith for 23 years and bedded a bunch of accurate, rifles.
Hope this helps. PS; don't forget, to "prop up" ( support) the Barrel in front of forearm to keep the barrel from "sagging" while, Compound is drying !