Originally Posted by cummin_un_glued
has anybody tried these in a 1-9?
The required twist rate for a given bullet is a function of several things. Most important are the air density and the bullet muzzle velocity . At supersonic velocities most bullets are more stable the faster they are driven. The force of air trying to upset the bullet is higher but the spin rate is faster and is a little more important.
Cold dry high barometric pressure air is denser than warm moist low barometric air. Denser air requires a faster twist rate. A 9 inch twist barrel with a 280 or higher velocity cartridge shoots 180 SMK and Bergers just fine at the mile plus altitude in Arizona where I shoot most of the time. At that altitude even sub freezing temperature is not a problem. At lower elevation and colder temperatures I can't say.
The best way to find out if a given bullet will be stable in your rifle in the conditions you'll be shooting is to shoot some long range targets for group size in conditions with a little higher air density than you expect to hunt in. Asking on the Internet if they shoot OK or using computer stability simulators like McGyro is is far less reliable.