Hi guys, I have learned a little from reading posts here and looking at RealGuns.com.. The basic premise is think of rate of twist = spin, and think how much faster you would have to spin a long salami (long heavy bullet) than a football (short lighter bullet) to stabilize it at a given velocity.
My personal experience was a TC factory 15" .243 Encore barrel would not stabilize 100 gr bullets cause the twist is 1 in 10". I tried factory and hand loads, but with not much success. The 85Gr are great, because they are shorter and require less spin to stabilize.
Playing with the RealGuns.com program I found out a 1 in 8 twist was needed for the velocities that I was getting for the 100gr.
I switched from the .243 to the .260 Remington (TC Factory 15") which has a 1 in 8 twist and now get groups around 1 - 1.5" routinely with 120gr bullets and the best groups run about .075" @ 100yds.
I have not tried lighter shorter bullets with the faster twist, but hope that I can develop a good chuck hunting load for the .260 without loosing accuracy.
I hope this helps.
Sieze the moment. Rol