Original percussion hammers - cast,forged, what?

Have a couple of originals with missing chunks due to erosion (?) of the portion of the hammers that strike the nipple. Seems to be common as I've had others in the past with the same issue. One is a good shooter - English single-barrel, half-stock 12 gauge that I enjoy hunting with, but the hammer has eroded to the point that cap fragments fly off and endanger my eyes.

So - out of ignorance, I ask ....would it work to have someone add material (weld/braize/?) then file down to the original configuration? Back in the day (mid-late 19th century), did lock makers use cast iron parts or somehow forge such parts? Suggested repair? Thanks in advance for advice.

Weld then file is how I’d go about it. The old guys probably forged them then filed to finish. Braze would be less desirable fix.

Gents, having made replacements for originals, I can assure you that they were forged, and then had extensive filing and finishing. At my old shop in LA (now long gone due to the liberal city government) we had original un-filed forgings. I sometimes had to work from engravings of the very early guns.
Filing, shaping, cutting the tumbler square in time (use a try hammer) and heat bending to alignment. then all the finish work.
On your original hammers, I strongly recommend TIG welding. Not brazing.. the nose cavities are heavily contaminated with rust, probably some mercury
and definitely lead from modern caps..maybe a little copper.. The hammer nose needs to be sand blasted down to clean metal for a decent weld.
The problem with the early steel when welding, is gassing..that is, the base metal wants to oxidize the uneven carbon distribution, and turn into carbon
monoxide in the arc.. Results, pits in the weld. Preheat the hammer, and then use standard chromoly TIG rod, as it will give a little solution to the old steel, and help with the pitting. Do not use the Brownells nickel bearing rod..bad results on old steel.
You might have to weld a little, clean up and weld a little more...One caveat, the new chromemoly will not be a color match to the old steel..finish the filing and machining on your hammer. If you don't preheat enough, you will likely get un-file-able hard spots. Also post heat after welding. Best of luck...

All that Philip said; 60 years ago Mick Smith, ln Sydney, had lots of original rough forgings of muzzleloader bits, particularly hammers and standing breaches.
Over the years I used a number of these, the hammers were usually some sort of steel and the standing breaches were iron.
Repairing hammers though I used the oxy torch and mild steel rod to build up the cup.

Colonial Boy, with you!.. I should mention that a torch is good for this. slightly reducing flame burns up some carbon. Mild steel rod helps avoid hard spots. I have been doing TIG for so long, I forgot to mention other process..My apologies..

I have heard of turning or filing a section of steel rod to match the diameter of the original hammer nose, cutting off the worn section and then silver soldering on the new section. It will leave a slight ring of solder that will show the repair but can be done by nearly anyone.

Crisco, not a bad idea, as long as you use an active fluoride containing flux, and pre-tin the surface with silver solder, it should work well.
Wish I had thought of that! Just file and contour to match, but watch your hammer nose alignment. I think heating and bending the Hammer for alignment
would best be done before repairing the nose..Just a guess however..

Thanks to everyone for the replies. Been gone a few days without internet access. I can still use files for some work, but welding/similar has never been in my skillset. Now, to find someone willing to fool with such a project. Both hammers function, fire caps ok. Thanks again.