30-30 bullets keyholing
I'm having trouble with 110 Gr. bullets in a Marlin 336 30-30. at 100 yards The bullets are tumbling and going through the target sideways. The rifle was built in the 70s and has a micro-groved barrel.
The load is at the top end of the load table with an estimated bullet velocity of 2600 fps.
The bore and rifling appear to be in good condition.
I would appreciate any insight in to possible causes and solutions.