There are many different 'levels' of instability. Turning in the air is easy to see, but barely stable in the air can be very accurate at close range - to 200yards. Just ask BR shooters who use barely stable bullets to print tiny groups.

Trouble with barely stable bullets is they don't travel in a straight line inside the game - what started off as a rear to front sot, might turn out the side of the leg just after impact, or turn on a rib on a broadside shot. Barely unstble in flight, is totally unstable after hitting. The bullet must be completely stable to maintain straight-line tracking.

If there is any doubt, use the bullet weight and length that made the gun famous.

I-to like heavy for diameter bullets - but I also like the bullet to travel in a straight line after impact-I don't care what it hits, I want a straight line. I've never had trouble with proper weight and length bullets.

This goes for all guns, including ML's.