This thread started with a question regarding what is very likely a cracked frame Flues, and the discussion, and pictures, thereafter were relevant.

A.H. Fox Gun Co. made it very easy to choose loads; from the 1914 catalog courtesy of David Noreen. And shell boxes at WalMart still are marked by ounces and Dram Eq. Unfortunately, IMHO ignoring the shell length specifications is a problem. Bell's study was of 12g loads; there is no modern data for 2 3/4" 20g or 16g shells in short chambers; esp. regarding the 1 1/8 20g loads available today, like the Federal Premium Wing-Shok.

[Linked Image from photos.smugmug.com]

Here's Remington's, also courtesy of Dave

[Linked Image from photos.smugmug.com]

Parker, Lefever & Hunter Arms Co. provided similar recommendations, and if one had the curiosity, the pressures of these loads are found here
https://docs.google.com/document/d/1F2sQuPm05IE4VWYYnCkvuXmYEzQoWd_SQgaAfUOZEFU/edit

I don't have a similar chart from a Tobin catalog, but Tobin did say the barrels were "warranted with all nitro powders where properly loaded ammunition is used" and it would seem to be reasonable to apply the load recommendations of the other makers

[Linked Image from photos.smugmug.com]

https://sites.google.com/a/damascusknowledge.com/www/home