Got the springs from Grainger last Friday. Did the change out and went to the range on Saturday. Did fine with the Hornady Black. But, tried some Monarch. Thought it was Privi Partizan re-branded, but it is made in Russia. Anyway, without the small inner spring, would not fire the Monarch. So, I imagine it would be the same with Wolf or any of the other foreign ammo. My guess is they are made with harder primers. I put the small inner spring back in and then put some washers on the stock bolt to lessen the compression. Would not fire the Monarch with any washers on the bolt. So, ended up using the Grainger spring and the small inner spring, as I want the rifle to be able to fire any ammo.