A rule of thumb is:
The Faster Twist will stabalize light bullets, the slower twist will not stabalize heavy bullets.
Meaning a 1:7 can shoot 80-90 gr bullets, but it will also work with 50 gr bullets.
A 1:12 will stabalize the 50-55 gr bullets but will not stabalize the heavier bullets.
For an example, the 5.56 Mann device (used for testing military ammo) is a 1:7 twist. The ammo used to check the Mann is 52 gr Match bullets.
The below chart shows the army shooting 300 yard targets with heavy bullets in a 1:12 and light bullets in a 1:7.
If you have a choice, go the fasted twist you can. You can shoot 50s to 90 gr bullets.
Many say that the fast twist will over spin lighter bullet causing them to come a part, this may be true if you use light 40 gr pills designed for the Hornet, but any good quality 52-90 gr bullet will work with the faster twist.
