Many things can tighten up groups,different powder,amount of powder,seating length ect
Start with one thing at a time,don't do more than one change at once .
For seating depth I like to kiss the lands but magazine constraints may prohibit you from doing that.
If you start at the start (the lands) you only have one direction to go if you need to adjust.
1" is the best I get with the 120gr TTSX,I've better groups with R15 and Varget
the 120gr Nosler ballistic tips will give you best groups 9 out of 10 times but how much better than 1" do you need in a hunting rifle?