... 1:7 twist rate...
It takes more effort for me to spin my 17-year-old son on a tire swing than to spin my 13-year-old daughter.
Overcoming the rotational inertia of a bullet works the same way. A heavier bullet needs to be spun 'harder' than a lighter bullet to get to a particular rotational speed.
As a general rule, from a barrel with a 1-in-9 twist, as your bullet weight moves up from the 50-grain range to the 60-grain and 70-grain ranges, your bullets will leave the barrel spinning slower.
As you move to a 1-in-8 or a 1-in-7 twist, the heavier bullets will spin more quickly. Of course, so will the lighter bullets.
When you are shooting lighter bullets out of barrels with a faster twist, the higher spin rate may affect your accuracy just as much as a slow-spinning heavy bullet. This can often be overcome by using match-grade bullets.
Test fire various types of ammo from a bench rest (10-round groups) and find out what seems to work best for YOUR rifle.