Just doing a little research being I don't want to get into a situation like I have with my CZ 75-TS. My CZ is a great gun but magazines are specific to this gun and this gun only, unlike the other line of CZ 75's/85's where they have common magazines and other part that are interchangeable.

 

For the STI guns that take double stack mags, are they all interchangeable between different models?

 

The gun that I am really looking at at this time is the Executive but don't want to get into another that I can only use the mags for that gun, I will probably get another STI down the road and if it a double stack, I'd like to not have to do another full set of mags all over again for what they run.

 

Also are factory or factory tuned mags the best or are there better options or preferences, if so why??

The deal with sti/sv mags is that they all interchange. At least as much as they work right without a little tlc in the first place. That's mainly do to low volume of production, and tolerances for the molds for the grips and mag dimensions stacking.

 

By and large, I find the 15 round 126 mags with the factory follower to work well. The shorter tubes seem to be more rigid, and thus you are more likely to get one that is in spec. Most of the really bad problems seem to stem from people trying to make the 140s hold 21.

At first when I read "STI" I was thinking you meant "Sexually Transmitted Infection." I was going to recommend going to a doctor, rather than asking for advice on the boards.