A couple things to address in this post.
9mm-40S&W. One only has to look at the amount of depts that have dropped the 9mm in favor of the 40 S&W to realize what the preference should be. 40 S&W is not that much more expensive to shoot than 9mm anymore. 357 Sig is alot more expensive to shoot. although it is a great round for duty/self defense.
Glock. I have carried both Beretta's and Glocks for duty and far prefer the Glock. Someone mentioned a Glock jamming up. The likely cause for this would be what is referred to as "limp wristing" when shooting it. This will cause the Glock to jam more than anything. A stiff, locked wrist will likely eliminate that problem. I would far recommend the Glock over most guns....after all, I do trust my life to one
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I am not familiar with the S&W, but hopefully its not anything like the Sigma....a couple friends had them and sent them down the road. I only shot one and didn't likea thing about it.
Glocks triggers are easily adjustable by areliable gunsmith. Find a refurbished one and it will likely be one a law enforcement agency traded in and try it. Ibet it's trigger is different than a factory trigger.
I have heard good things aboutthe XD, although most whom I have talked with complain about it's bulkiness. I have never shot one myself.