An 1892 Lefever Arms Co catalog has a shot chart in it & lists;
Merchants Shot Tower Co, NY #7 = 225/oz
Tateham Bros, NY #7 = 291/oz
New York Lead Co, NY #7 = 278/oz
The Leroy Shot & Lead Mfg Co, NY #7 = 278/oz
Thos W Sparks, Philadelphia, PA #7 = 305/oz
St Louis Shot Tower Co, St L MO #7 = 306/oz
Dubuque Shot Mfg Co, Dubuque IA #7 = 323/oz
Selby Smelting & lead Co, SF, CA #7 = 303/oz
Chicago Shot Tower Co, IL #7 = 323/oz
St Louis #3's were about half way between Tatham #'s 3 & 4 @ 116/oz.
I haven't checked but I believe Dixie Gunworks catalogs have a comparsion between Eastern & Western Buckshot. A long time ago I picked up a 5lb bag of .32cal buckshot for use in a .32 cal ML squirrel rifle & it was marked #4. I think I got it on a trip by Dixies.
