In July of 2020, I purchased Winchester 25-20 brass from Buffalo Arms. Brass arrived in a timely manner, packaged in Winchesters current 50 each plastic bags. Price was .344 including shipping.
How they managed to procure a scarce cartridge case, in the middle of a pandemic was mind blowing. Dave Gullo at Buffalo Arms in Idaho might be a better source for 25-20 Winchester brass in regards to a group buy.
Rick
PS I bought a lifetime supply at the time. My guess is, someone found a barrel of unpackaged brass at the Olin warehouse. Packaged it and Buffalo Arms bought it all.