Yes, I am an old man, but... 1:10" was standard for the past 50 years. Before that it was 1:14" which frequently wouldn't stabilize 100 gr bullets or heavier. However, bullets today keep getting longer, with less or no lead, and plastic tips. I believe today I would go with 1:9" twist. Todays plastic-tipped bullets are so well made that there is no worry about over-stabilizing them in faster twist barrels, especially in a 250 Savage.
On the other hand, I have never encountered a problem with 1:10" twist in 250 Sav, but I really don't go any heavier than 100 gr in the 250. I have a friend that uses 115 gr for deer in his Ruger UL 250 Sav with no problem, and very accurate with conventional cup and core soft-points. The 1:10 twist is standard, so to speak. If 1:9 was a much more expensive option I would be happy with a 1:10 twist. A happy old man.
Hope that helps a little. Have fun.
Nifty-250
"If you don't know where you're going, you may wind up somewhere else". Yogi Berra
