Fishtail top lever right hammer.
 

Here is something I do not recall being mentioned in TPS regarding fishtail top levers. And I do not recall seeing it anywhere else. This photo is of a right hammer from a 1 frame top action with fishtail lever. It is notched to that the lever will clear with the hammer cocked.

Attachment 29015

Maybe for the smaller frame size?

Very interesting

We have discussed that feature here before. It is unusual but not rare that a gun with the fishtail lever has the right hammer filed like that.

I have a few 0-frame 16's with the fishtail lever that are not filed like that.

My 0 frame 16 does not have a fishtail top lever, and won't open with the right hammer cocked, but I suspect it would with a notched hammer.
My 1 frame 12 has a fishtail top lever and opens with the right hammer cocked, without the notched hammer.
I'm guessing that the notched hammer was for guns with straight levers.

But the one Brian shows has a fishtail lever and a notched right hammer.

I guess filing the hammer was less work for the gunsmith than bending or replacing the top lever. I'll bet the original owner used the gun for decades and never noticed the notch.

Yes sir, I noted that. There have been lots of posts stating that some parts were being 'used up', the hammerless guns with fishtail levers for example. I can't explain why a gun would have both a notched hammer and a fishtail top lever because, a) I don't have one, and b) there seems to be so many exceptions to the rules. Perhaps the gun in Brian's hand originally had a straight top lever and at some point it got changed. Who knows?

My hammer guns are lifters; don't have to worry about that stuff.

I notice some of the hammers are spread on some of mine to accommodate the lever. Agree that lifters are more user friendly