My tuppence worth.

Pro mags have really poor feed lips and need a lot of tweaking out of the package (plastic bag) to get them working properly. The metal is quite soft and the lips get out of adjustment easily, they tend to move and open up with extended use.

Stamped out en mass, not the highest quality. but they work and fill a need. Good for a stop gap if you lose a mag, but most owners end up replacing them. Not many repeat customers for Promag, but saying that, there are many people who are perfectly happy with them.

The metal appears to be some form of a low carbon steel, it isn't that rigid or robust.
I recommend staying away them. I think that you would be disappointed with the end result.

If you are going to put the time and effort into working one into a five rounder, I would save some later grief and use an original, there are literally thousands of spares still around.