The model numbers in the 30s are three diget (exp. 6020) or start with HB (eg. HB253) The 41 cat has some BF models and some three diget. The 45 and after, they are all HF models.
The hammers are hard to date, model numbers on the heads show up in what seems like the early 50s. The model numbers on some were stamped on the bottom of the handles (pic). The script and colors do change. Below are some pics, in what I think may be the order in which they were made.
The nice thing about collecting these is that you get to use them. they come in very handy in tool box repair.
His hammer is probably a model HB253 from the 30s. notice the small print in the Blue Point name. has also KENOSHA WIS USA printed on it.

Probably a HF252. Has small print Blue Point and also Kenosha Wis USA. Back side. DROP FORGE 152G. This is a double angle dinging hammer, last shows up in the 41 cat as a model BF605. When you hit it on something, it rings like a tuning fork, this one has be restored.
