Backed up for posterity.
"You'll want nylon or pc for this part. you can make this with pla+, but I would use the anti walk pins that come in a kit. it will work for a little while, and you can use the mil spec springs on this part! 100% infil. and you can add a weight to the hammer, by drilling a hole in it and gluing a lead weight into it. also Not my original design, it's an open source file."
I have no idea where I got these files, but there they are. Comes with a readme from the original author (zucc_this) and a blueprint for the rail piece. Remixed from FMDA 19.4.