Lazzeroni calls his round a 7.82 but it's a .30-caliber.
So you are getting close to 200 fps more out of the Patriot than Winchester is advertising for the WSM. However, the water capacity of the two cases is exactly the same! Could it be that the WSM is really capable of duplicating the Patriot? That Winchester, and susequently the loading manuals are doing their normal overly cautious thing?
If not, maybe I made the wrong decision in spending two grand for a custom rifle in the WSM when I should have reamed it for a Lazzeroni!
My vote would have been to go for the Patriot. I would not rely on Winchester "test" data at this point in time. The manufacturers always seem to squeeze more fps out of their cartridges than us mortal reloaders. The jury is still out on the Short Mags.
If you look at the listed top loads for the WSM they are about the starting loads for my Patriot...about 4 or 5 grains under my max.
Recent article I read by Boddington confirms this by putting the Patriot closer to the Weatherby than either the .300 WinMag of .300WSM.
Don't feel like you made a mistake in getting the .300WSM....if I had known they were coming out I may have waited but as it was, I wanted a "little brother" for my 9.53 Lazzeroni HellCat.
Yes the Patriot's brass is thicker than the WSM: Yes base is larger. But the fact remains that the case volumes are the same. To my way of thinking, this should translate to similar velocities.
I suspect that as folks become more confident in loading this round, that achieved velocity will inch up.
I certainly hope so.