In simple terms, a guns price reflects ease of use and longevity. Basically, spend more and you get a gun that is easier to shoot well (ei. better trigger), has more features (ie night sights or rails), and is easier to maintain (simpler field stripping and dis-assembly).
Since it is a S&W site and your obviously looking at the S&W Sigma and M&P, it provides an excellent illustration of the old adage that "you get what you pay for". Both the Sigma and M&P have proven to be reliable in function, meaning they don't tend to jam and can be trusted to go Bang when you pull the trigger. However, the Sigma is a bit notorius for having aa heavy and gritty trigger that is difficult for a new shooter to use with good accuracy. In contrast the M&P has an excellent trigger that is easy to shoot well with and it also features a grip that can be modified for sizing to the shooter by replacing the insert.
To my eye, the SD series offers a superb balance between price and features. Reports I've seen indicate the trigger is equal to the M&P in terms of feel and it also ships with a tritium front sight (it glows in the dark).
The only question is it's reliability in terms of feed. I am inclined to hold off on purchasing any newly designed pistol because much too often they tend to have reliability issues that need sorting out. However, I haven't seen many complaints about the new SD so right now it looks as if S&W has produced a winner right out of the gate.
IMO the only area where the SD might be lacking is in the grip, it doesn't feature replaceable inserts to allow changine the size. However, if you have hands anywhere near average, it's a feature you won't use.
If you can find an SD available for rental, I would strongly suggest trying one out before purchasing it. Fact is the only guns I've purchased without a rental test drive have been my revolvers becaue they have been so unchanging in terms of fit and function for so many years.
As for your question in regards to ammunition. One key difference is the cost, premium Self Defense ammunition costs roughly 3 times as much as range ammunition. What you gain with that higher price is a higher degree of lethal wound potential. Range ammo will basically drill a nice clean hole through the body of someone who has been shot while a good premium SD round may not even leave the body, what the premium ammo will do is cause massive bleeding. When you're trying to stop someone intent an doing you harm, you want something that causes massive bleeding because the blood loss will cause a loss of consiousness. Note, some states, in particular New Jersey, prohibit owning any hollow point ammunition, so if you're a NJ resident simple range ammo is your only choice. In that case, get a 9mm and shoot the lightest bullet you can find, it may ricochet off internal organs and prove more effective than a heavier bullet. If you live in a more reasonable state, get the 40 caliber and choose a 165 or 180 grain "heavy" bullet, there is less potential for over penetration and they do have some degree of "knockdown" power. However, please remember these are handguns and "knockdown" power is mostly a movie myth. At best about all you can expect is perhaps 3/4 to 1 second of "'shock" when you hit someone in the body, after that they'll probably be shooting back until you hit them again. This is the reason why you'll see reports of Police shooting someone 12 or even 20 times, it's because that is what it took to get them to stop shooting back. Fact is a human being can be pretty darned tough and if you don't get lucky with a CNS hit, it can take lots of hits to stop them.
Now, about bullet types.
First up is "Ball" amunition. This is a common range ammunition that originally featured a rounded nose, hence ball, but today also may have a flat on the nose. Good for punching paper, decent for hunting on larger game such as deer, and notorious for going straight through human targets with little bleeding.
Next up are Wadcutters or Semi Wadcutters. The Wadcutter was originally devloped to punch nice clean holes in paper targets. It's a straight round chunck of lead flat on the front and may be either flat on the back or cupped. Those sharp corners of the front produce a very cleanly cut hole in a paper target. Not soon after they were introduced the Police discovered that those sharp corners also increased bleeding in someone shot with a Wadcutter. A bit later some enterprizing police discovered that mounting a hollow based wadcutter upside down was even more lethal and the hollow point was born. The Semi Wadcutter has a reduced diameter at the nose with some slight tapering on the nose. This impoves aerodynamics and improves the long range effectiveness, making it more suitable for hunting. However, since it retains some sharp edges on the nose it does produce more bleeding in the wound path than ball ammo. For a very long time the semi wadcutter defined the standard Police issue round because they did work somewhat well, IMO because in the 38 spl. they tended to tumble once they hit someone. However in a faster moving caliber they tend to act more like Ball ammunition and bore straight through.
Then there is the Hollowpoint, which today predominates Self Defense ammunition. As noted it all started with an upside down Wadcutter. However today's premium hollow points employ enhancements down to the microstructural level. One early problem with hollow points is they tended to fragment and produce very shallow wound channels. All those fragments made it a pain for ER docs but they weren't real good at stopping an assailant. Today you can find a large variety of hollow point ammuntion and they are NOT equal, you get what you pay for. The Winchester Silvertips are cheap, based on "old tech", and tend to fragment. The Winchester Ranger-T cost a lot more, are "new tech" and do NOT tend to fragment, which means they produce a deep, heavily bleeding, wound channel. Basically, Silvertips are fun for blowing milk bottle apart, Ranger-Ts are what you keep loaded in the House Gun. BTW, the Speer Gold Dots are equal in both cost and stopping power to the Ranger-T.
Bottomline, if hollow points are legal in your state, plan on spending 80 cents to 1 dollar per round for a good modern SD ammo, any less and it may fragment when you need penetration.
I am brand new and am trying to learn before my first buy my first pistol. I am looking for a home defense and target weapon. I know the bullets are different sizes but I am sure it is much more than that. I am 200lbs so some kick is ok but I still want to be accurate and not be exhausted after shooting!! That's why I was thinking to stay away from a .45! I have some friends with Glok's but I don't know they seem to be for different applications then what I am looking for????
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