Originally Posted by ndtiger
I am looking at getting one of these but am somewhat confused on the different models. I am interested in a 4". I see taht some come with 10rd., 12 rd. or 15 rd. capacities. Are these just different mags or different guns alltogether? What are the different models and advantages?
The website for them does not clear much up.
XDs come in three basic barrel lengths 3", 4" and 5", compact, sub-compact and full size grip lengths, and several calibers including: 9mm, .40S&W and .45ACP, XDms are available in .40 and 9mm only. The combination of caliber and grip size limits capacity, however, as stated, several states artificially restrict mag capacity. To overcome this, many of the major gunmakers produce 10 round magazines which also serve as the standard mag in their conceal carry size weapons.
Even guns wth a short grip can accomodate a larger capacity magazine by the use of an Xtension boot that covers up the bare metal hanging out of the grip and gives you a better hold on a now longer grip, short grips are hell on guys with big hands. Guns by design have no inherent capacity, in fact the capacity of every semi-auto made is 1 round, the rest are held in the magazine until chambered.
Barrel length affects accuracy due to the longer sight radius on a longer barrel. It also has an affect on muzzle velocity. In general a longer barrel is more accurate at distance and the bullet leaves the muzzle at a higher fps. The other side of the coin is concealment, longer barrels are harder to conceal and more training is required to cleanly draw a longer barrel from a holster.
In your example, the 10 round was either a CA compliant or a subcompact, the 12 round was a full size XD and the 16 round was an XDm. Sprindfield also makes a .45 ACP compact that ships with a 10 rnd and a 13 rnd magazine, 2 10 rnds for CA.
Best advice I can give is to try out a few different models and see what feels best to you, whether 4" or 5" is an issue and what grip you are comfortable with.