the s&w sigma and the glock are definitely not the same. the sigma is s&w's entry level semi. fit and finish is lessened is all. that said there is nothing wrong with the sigma. it works fine and will do the job. never hread of any problems with it. good entry level gun. i would rather have the sigma over any taurus.
sigmas are real nice guns for the price. i have a friend with one. i have shot it. the trigger pull is a little heavy but other wise its real nice. pluss you can get a new one in several diferent callabers for about $325. thats hard to beat in my book. i have also fired the springfield arms XD and XDM, wich are the ones you moast often hear people talking about. they are verry nice, and if you shop around you can find nice used ones for about $450. hope that helps.
I would like a .40 cal but 9mm comes first for plinking practice. A cal exchange kit is a good idea to go .22 for cost reasons. With a spare slide, barrel, mag, recoil spring/guide you can convert your handgun in 2 minutes flat.
Glock interchanging calibres for a model 22, 23, & 27
It is true that you can purchess a new barrel and get the choice of firing both the 40 S&W and 357 Sig in the same pistol. The cartridge base is the same and the recoil pulse is close enough the the standard spring works fine. The mags are interchangable as most of the 357 Sig dimentions are again the same as the 40. I have fired both, it seemed that the 357 cycled faster with less muzzle flip. That was probibly due to the fact that I was shooting a lighter weight bullet in the 357 sig which would be operating at a higher velocity. I have been through the Glock armorer course and as a non gunsmith the pistol is very well thought out. Having said that I still prefer the trigger on my Custom 1911 Springfield 45 to the less crisp springy trigger in my 40 cal Glock 35.