Re: New build-chamber and barrel contour questions
Get a chamber made to SAAMI specs; no tight neck job. When the 7mm Rem. Mag. was popular for long range prone matches, folks shooting the best scores used that chamber or one a virtual copy thereof. When good, heavy, long match bullets were finally available, they shot sub 3/4 MOA at 1000 yards from both brand new cases as well as properly full length sized ones. The one I used decades ago tested a bit under 2.5 inches at 500 yards with new cases and a special select lot of Sierra Bullets' 168 HPMK's; the only range it was test fired at. When I shot it in a match, the wind was pretty wild. While it held good elevation at 1000 yards, its windage was not anything to write home about.