Since when is blazer brass hi end stuff? I think spree law man is better than blazer .
But have you fired WWB through a Shield? Maybe the Shield has a lighter firing pin and can't handle anything less than premium ammo reliably.
I have been using nothing but manufacture reloads, had 2 FTF that is with about 1K. I would not consider the Shield picky at all, not when you consider how many reports with NO FTFs.
Send me all your FTF's and I'll see if they work in my 3913.....