When I was at the Conservation lab of the National Library of Wales last week, I noticed they had a very fine example of a Harrild & Sons beating hammer. The other side of the hammer, in equally impressive large letters reads “LONDON.”
The polished rim is similar to the Hickock I own. It is a bit curious why the rims are polished so far up- I can’t imagine the hammer being used on its side. The hammer weighed almost 10 pounds (4.5 kg.) and the head had a fair amount of belly and 4.75 inch (12 cm) diameter. The handle is a replacement.
The Bodleian library’s blog, Oxford UK also has a nice unmarked beating hammer pictured, which looks early 19th century to me, just guessing from the smooth casting and more gradual transition from the face to the segmented head.
But beating hammers are fairly hard to find, so far I know of only a few. I’m going to atttempt to keep up to date a census of know examples, any other examples (and photos) are much appreaciated.
CENSUS OF BEATING HAMMERS
American Bookbinders Museum. (not yet accessioned) Hoole?
Bodleian Bindery. 19th century unidentified, bell shaped. Harrild?
Boston Athenaeum Conservation Lab. Looks like a Hoole.
Cambridge University Conservation Lab. 19th century, bell shaped.
Harcourt Bindery, Boston. Very large 4″ face. Illegible markings” MAR—SON & Co., BOSTON”
Anne Kahle, Capriconus School of Bookbinding and Restoration. Hickock.
Richard Minskey. A medium and large Hickock.
North Bennett Street School, Bookbinding Department. I think a Hoole.
Jeff Peachey. A small Hickock, an unidentified make (possibly not even a beating hammer) and a French style one.
St. Catherine’s Monastery Bindery, Mount Sinai. Two reported hammers.
The National Library of Wales. A Harrild & Sons.
Peachey Conservation 
I haven’t seen a Hoole hammer or an image of one. The American Bookbinders’ Museum hammer is not a Hickok and is unsigned. is a bit smaller than Anne Kahle’s Hickok hammer, if I remember correctly, has two strongly curved faces, and has a barrel-like body with the two faces larger in diameter than the largest diameter of the body. It is in bad condition to the point of unusability, with both faces chipped and broken around the rims. I believe it shares a provenance with two of your hammers.