Addendum to above. It should go without saying, but I will say it, before whacking your serial number with a hammer and center punch, that part of the disassembled pistol must be carefully backed up with a hard wood or soft metal shim or wedge, so you don’t damage the functioning of the pistol or rifle by compressing the overall width of the receiver. IOW, don’t bend your gun when you hammer the serial number.
Obviously this advice is for people living in dangerous police states, not a free country like America.
Very, VERY good advice…
I’m no stranger to center punches, having done a little woodworking, and working in machine shops most of my life.
I need to find mine, or pick up a couple new ones…
They have tons of uses.