I’m a green horn engraver so I haven’t engraved a Springfield slide but I have done gunsmith work on them for a while. The slides are hard. Every sight cut I have to use a new carbide end mill and dovetail mill. They are not as hard as the Glock slides though. Hope this helps
Forged stainless is some really tough stuff. I would suggest a carbide graver with a steep face angle and a dubbed point. I would do a test cut someplace such as the inside of the slide where it does not show or hurt anything. Slow is the word.