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Otto,
The 70 gr TSX likes velocity. I have a not well articulated theory that roughly equates to quantum theory. Basically some bullets really begin to work well above some velocity threshold, while others stop working well once velocity threshold is exceeded. I like hard data when I can get it. The problem with hunting bullets is that people rely on gelatin tests that vary from field observable results. The problem with field results is accurately quantifying the results. Having said that if your CZ has the 16” barrel your expansion and tissue damage is significantly less than the 20”, the bullet (along with the Nosler 64gr bonded) shine in 22-250. With a 1-9” twist the stability of the 77gt TMK may work with one density altitude (low – high/hot) and then not stabilize in colder temps at sea level.
I like the 03-a3s, they are just so smooth. Recently picked one up that had been “sporterized” for really cheap. The drill and tap job was butchered and it gets worse though the NDI was sound so many dollars. The externals on most older rifles have lots of variations which result in accuracy issues. Basically you are introducing stress into the system.
What you want is as straight, parallel, perpendicular, and stress free as possible. You can solid shims out of SS shim stock or even aluminum cans (sides and bottom are different thickness) and take up the smaller differences by bedding the base with liquid steel. Both Brownells and Midway sell ring lapping kits ($20-30) that are easy to use. It is surprising the number of wandering zero and erratic accuracy problems that are solved by removing most the stress.
S/F, FOG
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