Randy Robinett's Advice to me...
Quote...
"All of my 30 Cal., competition barrels, since 1997 have been 1:18". The 112s, and other bullets based upon the .925" jacket, are ideally suited to 1:19" twist ....
The 1:17 seems to have become the default twist rate, but, it provides a HUGE [gyroscopic stability] safety net - at 3000 FPS, the .925" based bullets, Sea-level Std conditions, it produces 1.9 Sg! A 1:19" twist would produce right at Sg 1.5 - the ballisticians "ideal" Sg target.
You will likely be quite pleased with the 18" twist."