Chris,

That looks like a very nice rifle. It should be fun to hunt with and just target shooting.

I have had 9,3x57r/360 brass. The only thing I noticed is that the rim is 0.060" whereas the 360 EX rim is 0.044 - 0.048". The brass almost seated in my AH FB, just the rim was just so slightly too thick to allow the block to close. The brass was from Buffalo.

I have a rifle in 9,3x57r/360 which shoots 360EX but sometimes misfires. I made some brass using thick rim brass and it doesn't misfire.

However, cartridges for early German and Austrian rifles were not unified so perhaps I was just lucky.