Re: looking for a load 220swift with 69grain matchkings
Kevin, Thats ironic about the 69 grain Sierra's shooting much better at around 3,400 fps than 3,500+ in your Swift, as I subsequently found that the 69 grain Sierra will shoot accurately up to at least 3,930 fps.
In 1988, after my experience with the 220 Swift AI, I subsequently built a .224 Clark using a Shilen 1 in 10 twist barrel, and achieved sub 0.5 moa accuracy with a variety of powders between 3,850 and 3,930 fps. Even at those velocities the 69 grain Sierra never showed a hint of coming apart.
After 1600 shots as a .224 Clark, that Shilen 10 twist barrel was set back and rechambered to the 22/250AI, and the velocity with the 69 grain Sierra dropped back to the 3,350 - 3,430 range. Accuracy is slightly improved with numerous groups in the .25 - .4moa range.
There are numerous improved versions of the .220 Swift, but the 40 degree shoulder version that I used certainly reduced brass flow to a minimum, and increased the capacity of the standard .220 Swift from about 50.5 grains to 55.4 grains. Hope that the above is of some interest. Brian.