t_montana9 saidSeriously, I'm having problems why you are considering the .357 Sig. For that matter, even the 40 S&W is a little troubling to me.
When I was in law enforcement, I was directly involved with the purchase of department issued weapons. We test fired numerous guns all the time with different rounds. I can honestly say that if there was one round that I would want to use in case I was defending myself or others against imminent threat of great bodily harm or death it would be the .45 magnum. In uniform, I carried the Glock 21 and when I was an investigator, I used the Glock 30. Glocks are perfect because they are extremely reliable and all you do is point it and shoot -- no safeties or catches to have to worry about. I still have all my Glocks, which include the 17, 21, 27, and 30 with the 17 being the oldest because when I started in law enforcement it had to be a 9 mm. I have never had a malfunction with the 17 and very, very few with the 21. The nice thing with the Glock is that you have plenty of rounds. Most 45 use single-stack magazines but Glock staggers the magazine to get more rounds in them.
After shooting the .357 Sig, I would stay clear away from it. The .40 is a decent weapon but where I work, departments are transitioning away from the 40 in droves and are going back to or turning to the .45 magnum.
If you want more information, Google Massad Ayoob, a well known firearm's instructor who has been called upon by the courts many times for his expert opinions in terms of weaponary and deadly force encounters. He hasn't met too many rounds or guns that he doesn't like but he always stands by his choice that the .45 magnum is the round to have.
I'm assuming your mean .45 ACP (Automatic Colt Pistol)/ AP (Automatic Pistol), as there is no .45 Magnum.
Some .45 rounds suffers from velocity deficiencies that prevent HP rounds from expanding.
Capacity is nice, but if you can't hit it with 10, 3 more isn't going to help you, you're just going to blow out three more windows or shoot three extra bystanders.
From my position the Glock is a piece of crap that people get so they can be tacti-cool.
You can't get worse then receiving a Glock back from their repair facility along with a call that they didn't fix it because there was nothing wrong with it, but just you never mind the handwritten note from the inspector, the Glock employee, detailing the workmanship failure.
The Glock line was a pooch over from the get go. The designer of the Glock was removed from the company because he was making trouble about the company releasing the firearm with deficiencies. The company quietly did agency direct repairs as they discovered the problem that the company already knew about.
The cops I know despise their agency issue Glocks.