Re: looking for a load 220swift with 69grain matchkings
Freebore, I am not doubting that you did, but I am amazed that you could get the 12 twist to stabilise the Sierra 69 grain HPBT in your .220 Swift.
In about 1986, I built a custom .220 Swift Ackley Improved (Rem 700, Shilen 25.25 inch 12 twist SS barrel) and was unable to stabilise either the 68 grain Hornady HPBT, or 69 grain Sierra HPBT, despite reacing velocities of 3,700 fps.
The barrel twist when I measured it, turned out to be a 1 twist in 12.10 inches, but I am sure that the extra .1 wasn't the difference between full profile bullet keyholes and stabilising.
There must obviously be other barrel dimension factors apart from the twist that play a part in the stabilisation of the bullet. Regards, Brian.