A dab of high end Loctite won't hurt.
Now you have the tool, you can be useful to other shooters thereabouts. All you have to do now is learn to do the countersink where required. Brownell's used to sell a tiny little inside reamer for the job, but it was expensive and delicate. Most gunsmiths just use a ball end on a Dremel. It takes care not to scar up the inside of the gun but is quick when you learn how.
I have a few facts and a lot of opinions.