Buffalo Arms carries hard to find and obsolete ammo for various old guns.
In my case, I purchased some ammo from them for a 100 year old rifle a while back, and finally got around to testing it out. I discovered issues with some of the cartridges, and got in touch with Buffalo.
They sent me a brand new box of ammo, problem solved, and great customer service.
Of course I am not affiliated with them in any way, simply want to acknowledge they did right by me.