As per the 7/300 Weatherby, I have had 3 or 4 of them over the years and still have one.
The Weatherby brass (Norma) and 7mm bullets made by many manufacturers, are very good and with high BCs,
That calber makes a fine Long-Range hunting caliber and it also held the 1000 yd World Record as far back as 1971 when a lady named Mary Lousie Daveto broke the record with a 7/300 Weatherby built by Howard Wolfe.
There are many loads for it but for hunting deer with in North central, PA in late November and early December. My friends and I always used 87 grs of H-870 or WC-872 with the 162 Hornady Match or 168 Gr Sierra MK. and Federal 215 primers.
I'm using 74 grs of IMR7828 in Norma brass with Fed 210 match primers and sierra 168 gr matchking in my Rem 700 action with a 30" Shilen barrel. Have not had an opportunity to crono the load. Did shoot a 7.6" group at 1000 Yards with this load. Remember start low and work up. Looking forward to taking my first deer with this gun at long range in Cameron Co., Pa this season.
I have been shooting 75.5 grains of H-1000 with the 168 MK at 3180. This seems to be working well, it will shoot an 8" group at 1000yds on a good day. I also have not used it on deer yet but I will for sure get my chance this year.