If I'm counting correctly five shooters, including the winner, were using Winchester LEADER shells --
LEADER 12-Gauge.jpg
and one the Winchester PIGEON shell which was offered from 1898 to 1907, both loaded and as an NPE --
Pigeon 1901 NPE Head, No. 4 primer.jpg
The rest used Union Metallic Cartridge Co. shells, TRAP loaded shells --
April 1901, TRAP loaded shells.jpeg
SMOKELESS loaded shells --
April 1901, SMOKELESS loaded shells.jpeg
and ACME NPEs --
April 1901, ACME NPEs.jpeg
I find it impressive that Ridgley B. Bond of Jessop, Maryland, ran them with the then new Baltimore Arms Co. gun.