Most states have laws protecting gun owners from prosecution when carrying firearms in their vehicles, and federal laws while they may declare post office property as "gun free" zones, in a state like Florida, good luck finding a jury willing to convict someone of felony possession of a firearm...
M&P 9C alternative (for a lefty)
I feel your pain as a lefty shooter. I own the M&P 9 and 45 full size, and the Shield 9. As a lefty shooter, I sometimes get frustrated with operating the slide lock on my shield, but honestly the only time I'm ever using the slide lock is when loading/unloading...
I posted on the same threat as David, and I've got the Thumb Break Scabbard and an Old Faithful Stage 3 Kit for my Shield. The only complaint I have with the Old Faithful is I wish their belt clips were deeper like Crossbreed's clips. I had a Crossbreed for my XD-9 subcompact, (Super Tuck) and...
I'm a leftie also, and got myself a DeSantis 3-hole thumb break scabbard to match the Bianchi Piranha thumb break scabbard I have for my M&P45. I like the DeSantis because it has the adjustable retention screw.
I also have a Kydex-Leather hybrid holster (similar to crossbreed holster, of which...