Has anyone tried converting their 10 round magazines into hi-caps??
What's involved??

Very difficult, virtually impossible, IMO.

Might I ask why you would want to do so? Hi-caps are available & fairly cheap these days & IDPA allows only the use of 10rd mags should you shoot a match.

I was recently given a sigma......Not a half bad pistol, but it has a 10 round magazine.
I've looked around but haven't been able to find any cheap hi-cap magazines for it. And I'll use it as a paperweight before I pay $40 for factory magazines.

Used 9mm Sigma mags are not as plentiful as the .40's since the .40 was adopted by more LE agencies that the 9.  If you post a WTB ad for used, full capacity 9mm Sigma mags, you will probably get some responses.  Try here and at the S&W Forum, too.

There are two different full cap mags for the 9mm (and .40 for that matter) Sigma.  The older ones, which were designed for the "F" full-size pistols, hold 17 rounds, stick out the bottom a little and have a larger baseplate on them to fill the exposed area.  Although they were designed for the 1st Generation guns, all Sigma magazines, in the same caliber, are interchangable.

So, they have the older mags as I mentioned and the newer mags which hold 16 rounds that fit flush like your 10 rounder does.

I've never paid more than $15 for a used Sigma mag and I never seem to have a problem finding them.  See?


BTW, that's an older, 1st Generation 17 round mag in the Sigma right there which sticks out the bottom, just so you know what I was talking about.

Thanks for the info.