I used one of my 325'S this year on a cow buffalo. I drew a permit here in Wyo. and hunted on the Natl. Forest off the east side of Grand teton Park and on the elk refuge. The Wyo. G&F, Park Service and National Elk Refuge completed their EIS on the Buffalo herd in the Park and Refuge last spring. They need to remove app. 900 Buffalo from the park area over the next 5 years and get the toal population down to around 500 instead of the current +1400. A result was allowing a limited# of Buffalo hunters to hunt into the elk refuge starting September 15th. for both cows and bulls.
I used a 200 grain Barnes TSX in front of 67.2 grains win 760. My chrono in front of the model 70 26" bbl says 3,012'/s. At about 50 yards 6" behind the horn she did not know the lites went out. She dropped straight down and the work began.
I have taken a muley buck and an antelope with the 325 also. The deer with a 200 Accubnd and the goat with a 180 Brnes TSX.
I have tried 4831 & 4831sc, 4350, H-4350, Winchester's WLR and 760. The granular powders take up too much room and by the time you get a load there is way more compression of the charge than i like. this short case and all of the 180 and 200 grain bullets have to be seated fairly deep for the magazine length and short throats that are in the chambers. My rifles only have about .110" over the max. cartridge length in the throat before the bullets are in the lands. I could have the throat llengthened in the single shot and it would help ease some of the loading problems with the short ammo.
The powder that will get you closest to Winchester factory ballistics is 760. I think the actual factory rounds are loaded with a factory blend as Hornady uses in their "magnum Loads" that are not available to anyone else. The factory 180 grains will chron @ 3,195'/s out of my M-70. I see more pressure signs with them than I like. Flattened Primers, A ridge from the edge going into the firing pin hole and a tighter bolt handle lift. Winchester loads them to Maximum pressures. My 180 grain loads run app. 3,160'/s and work well.
The 180 & 200 Barnes TSX's, Nosler 200 Acubnd and the Hornady 195 will all shoot under 1/2" at 100 yards from both rifles. The second rifle is an 1885 Hi-Wall single shot with 28" Bbl.