Welder, they are quite precisely made, but do have the inevitable 1911 quirks. Mag fitting and follower and ramp issues are not uncommon on any 1911/2011 platform. Mag tuning, good followers and consistent ammunition are your friends. One thing that none of my STI's like are reloaded ammo that does not pass the gauge test.
I purchased a casepro as some brass has been fired over 20 times... the extractor 'nick' can cause issues that the casepro solves.
As a rule, sloppy tolerances eat anything, but why feed a Ferrari 89 octane? Most problems can be traced to ammo and mags. Possibly feed ramp.
Edit: My GLOCK40 10mm will fire things that will stop my STI 10mm from firing. Does this make the GLOCK better? No, it is simply looser tolerances. And better mag design in the GLOCK.
