Bruce, I am willing to bet that the WSSM brass will be just as bad as the 300 WSM
brass that I delt with. I have heard that the Winchester WSM brass is getting better, but I am sure it will not be in the same class of the Norma 300 WSM brass I am now shooting. If I buy 300 pieces and do the sorting and preping I will come up with enough good pieces to wring out the 6.5 WSSM.
With the take off barrel that has a little over 400 rounds on it I can get into this project pretty cheap. And if it works, I should have only load tweaking to do with a new barrel, or at least know which direction to go which saves a lot of money and barrel wear. And if it dont work well, I can tell other shooters been there did that, and it didn't work for me. Maybe save some body else the time, trouble, money, and aggravation. There is something positive in everything.
As for powders, I am going to use the 4350 class of powders for the 123 and the 4831 class of powders for the 140 class bullets. GEZZZZZZZZ that is the fun, seeing what works with a new chambering.
The accuracy is certainly still there with the 300 WSM but it is copper fouling pretty bad in the throat area now. But it did shoot superbly in the July match that I shot in. It shot a 598-27X agg. I am going to shoot the 300 WSM in the August match in Tennesse, the September match in Tennesse, and the October match at the local club and then tear it down to start development on the 6.5 WSSM. When I start working with it I will keep you posted as to the progress or lack there of depending on which way it goes.