There are many state,county, and city laws in many areas of the country that limit the number of rounds a magazine can hold. 10 rounds is the normal round count in these laws allowed where high capacity magazines are banned. Thus, when the gun is ordered or extra magazines are ordered, the 10 rounders have to be used with that gun in that locality.
Where there are no such restrictions in the state, county or city,12 round count magazines can be used.
Check local laws in your individual areas for this. State,county,and city laws. Ignorance of the law or trying to get around it can get an individual some jail time and fines.
Usually.Confiscation of the CCW permit can follow.
Some how limiting the number of cartridges in a gun magazine is supposed to have an affect to deter crime.How has never been fully disclosed. At least no sane reasons have ever come forth. Nor are there data to prove crime is stopped or stymied by the this lowered round count.
Basically the goverment is saying that citizens can't be trusted with ammo or guns.
Criminals,who never obey the law, will not care nor follow these low mag round count laws.
This has nothing to do with the gun model differences, as there are none, other than the number of cartridges in those particular mags that come with the gun, allowed by law.
I'm lucky enuff to live in NY where 10 rd mags is the max by law. But it's very easy to get high capacity mags at every gun show I've ever been to. It'd be a felony here to get caught with a high capacity mag, although if it was made before the ban (or pre-ban as it's called) you can argue that its legal. Since I don't want to lose the right and priviledge of my CCW I'll just carry an extra mag thank you.
I like to refer to the 12rd mags as "standard Capacity" since that is what they were designed for. "High Capacity" would be anything over origional design ie 17, 18 or 20 in my Beretta that was designed for 15. I believe the anti's like to refer to anything over 10 as "High capacity" to make them sound more sinister and evil, thus needing to be controlled.