I found the chart of known 11 gauge Parkers and in fact,
no known 11 gauge Parkers were made on the top-action hammer guns. And they effectively stopped making the 11 gauge in 1877.
If anyone would like a copy of this chart shoot me an email at
dsromig@aol.com and I'll send it as an attachment in a reply email.
Also, "Parker Bores and Chambers" written by Austin Hogan but researched by Price, Hoover, Furnish and Hogan, can be found in
Parker Pages, Vol. 18, Issue 4 (Fall 2011) for an explanation of many of the things being discussed here.
This is another good reason to contact Mike McKinney for a copy of the
Parker Pages Digital Archive.
.