britt had the earlier Winchester version of your Browning 1885 Traditional rifle, I found that it shot the 255gr Saeco actually about 257gr cast from 25:1 lead/tin alloy bullet much better, could never get the 300gr Saeco to shoot near as well. My best load with the 257gr Saeco was 23 grains of H4198 and WW standard large rifle primers, bullet seated just deep enough to touch the rifling, came close to outright winning some CBA matches with this load and rifle.
I also used a older Hoch tapered 295gr .376" bullet with a load of 22.7 grains of Vihtavuori N120, Federal Large rifle primer, bullet seated about .250" deep (photo of bullet and it seated in case), this bullet shot much better than the Saeco 300grain bullet, have no idea what the difference was.
My rifle shot very well off the bench at 100 and 200 yards, I'd say it averaged 1.25" at 100 for ten shots and under 4" at 200 yds and when I did my part as small as 3", understand when I shot that rifle often it was in CBA with a 24x scope and on score targets.
Good luck with your rifle, I know they will shoot you just have to keep after it, bought mine to hunt with originally and when I started to reload for it and tried different bullets and powders I was amazed how accurate it was, been sorry every since I sold it, but the CPA Addiction hit me
and that was the end of the W1885.
MIKE-T