Two barrels one is a 1 in 8 and the other is a 1 in 12 twist. If I figure this right (I can be a little slow) the 1 in 8 twist is a faster twist (spins bullet faster)and 1 in 14 is slower.

If this is correct why does it matter? Is there a relation to slow vs fast and light vs heavy bullets?

I seems that I saw somewhere someone put together a list of caliber vs optimum twist rate i.e 270 = 1 in 10. Does any one have a link to this?

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If this is correct why does it matter? Is there a relation to slow vs fast and light vs heavy bullets

Yep a 1 in 8 spins the bullet faster. One revolution every 8" vs 14. The longer the bullet the faster the twist needed to stabilize it. You can offset a little slower twist with higher velocity on the smaller calibers. Go to the Shilen barrel sight they have their suggested twist rate for bullet weight per caliber and velocity. http://www.shilen.com/calibersAndTwists.html

Yes 1 in 10 for a 270.

If the twist is a little faster than optimal for a bullet weight, okay, no harm no foul unless, maybe you are a benchrest shooter.

If the twist is a little slower than necessary, then the bullet won't stabilize and may hit the target sideways, if at all.

There's one exception to the a little too fast okay rule, and that's with very frangible bullets. The Hornady SPSX series is one of several bullet lines (I think some of the Sierra's are the same way) that is designed for slower cartridges---the .222 Rem instead of the .22-250. They have lighter, thinner jackets to be frangible at lower speeds and over-rotating them can cause the jacket to tear apart.

LWD