Congrats
I have a .300 win mag #1, but I looked hard at those H&H's.
I think most all of the newer #1's seem to shoot very reliably.
If you really want to make that rifle scream, punching a #1S out to 300 Weatherby is easy (did it over 25 years ago, sold it to a neighbor, still trying to get it back...not so likely after he shot a bull that went 379 B&C!). No magazine to fool with, no reason for a short-necked magnum designed for a standard length magazine box.
Then again, you may like it just fine as is...
