With 1:12 twist you really want to be staying in the golden spot for bearing surface length. Now most manufacturers don't give this, its a case of researching online, but the rule of thumb is usually 150 to 155.5. Some other rounds will work, like the 168, 175 or 178 gr, but then again you still need to know the bearing surface length.

The Berger bullet stability calculator is a useful tool. I just done a quick comparison of a 155vld vs a 185 vld in a 1:12 twist and the 155 is stable, but the 185 is only marginally stable, bordering on unstable.

This calculator does not give the option of inputting bearing surface length but as its a drop down menu selection I'd assume its already taken into account. It only has a limited choice of ammo, all Berger, but if you were to find out what was stable, what the bearing surface length is, then you can check other ammo and do a search for ammo with the same bearing surface.

All of the above is only one aspect. This is why target shooting at up to 1,000 yards is so complicated. If you found the perfect round with the perfect bullet (factory) that is one battle. The next is consistency. While most ammo will perform within a certain margin there can be anomalies. Such as a round with a lower charge, not properly seated (imperceptible to the naked eye), or anything other of a dozen issues that will give you an unknown drop, flyer or other result that is not in keeping with the rest of the ammo you have.

Of course if you've gotten to this stage then you're already down the Rabbit hole so might as well go the whole Hog, but if you just wanting something to plink with try a few different boxes of ammo within this golden ratio and see which performs the most consistently. Don't forget that some ammo does not perform well at shorter distances, and only comes into their own at longer distances. Found that out the hard way when trying out ammo at 100 yards only for it to be crap. Decided to fire of the rest at 800 yards (after zeroing for the distance) and found they worked wonders at 800 to 1000 yards.

Feisar wrote: »

.........or the theory that some bullets need to "settle down", specifically VLDs..

This was the only "answer" I could find at the time of looking. Brian Litz talked about it in one of his books. Something to do with the gyration effect of the bullet "settling" or decreasing over distance.

In layman's terms (that I could understand) the bullet settles in flight over
a longer distance. The other side was who am I to argue with Brian Litz. The man has forgotten more than I'd ever learned.