Dan
I am of limited experience but agree on the one described as a flatter.
My reason being that the round end is very round( at least it was before it was beat on) I don't think my pics show that.
Thanks for all your help with Id.
How is a boilermakers set used?
Here's one more, small hammer, has an S set inside a diamond shape with a 6 or 9 stamped on the under side.
I've collected a lot of tools over the years mostly at garage sales . Here's a few hammers I'm not sure of the type. All help in ID, type and use welcome.