I appreciate the replies Gentlemen , firstly when I began this project I had opted for the standard Swift. When I contacted my 'smith and suggested it, he counter suggested the .220 AI.
Keith explained to me that as the standard .220 has a rather long tapered case and is prone to rapid case growth and requires frequent trimming. By fire forming into the 40 degree Ackley chamber the problem almost disappears and with consistent annealing brass life is significantly extended. Velocity gain is an after thought BUT I can tell the reader that after a session at the BR Range yesterday I think this particular barrel is a real 'screamer.'
The big surprise was the 60 Grain Nosler BT , conventional wisdom suggests that a 1:14" barrel will not stabilize a 60 grain projectile, however this barrel proved otherwise. 5 shot group measuring 1.051" strung horizontally but the impressive thing was the velocity. Quickload suggests 3,580fps for a load of 43 grains of RL17. Magnetospeed revealed MIN 3,739fps MAX 3,771fps
AVE 3,755fps SD 13 ES 32. The group was not impressive by Swift standards but shows potential for improvement.
I opted for the Kahles 3.5-10 x 50 simply because the shop selling it had Kahles on special with 15% off. The problem that arises here with quality glass and high magnification scopes is mirage.
Even during the winter months it can be a problem and yesterday when the Kahles KX was set a 10X, I had to dial it down several times to acquire a sight picture. However I must confess that I am considering another scope in the 4-16X range.
regards
Mike.