Could I take a high cap mag for say, a P226 and adapt it to fit in my P239.

Armalite does this with M1A Mags and as long as it will still work in the weapon originally designed for.

Is there any reason I could't do this with my Sig (other than logistics)?

Per ATFE, you can do that as long as it continues to work in the P226. If it doesn't, they consider it manufacturing of a new high-capacity feeding device.

... OK, while were at it. In a casual discussion today, someone said, "you cannot use a preban high capacity (USGI 30 rounder in this case) in a postban AR15.

... I stated the you can only sell a new postban with 10 pounder, [u]but you can use a high capacity in a postban[/u].

... I'm not sure I can defend that last part. Do you know?

Detachable mags and rifles are separate pieces. You can use and sell pre ban 30 round mags with a "post ban" gun. No problem.

Your friend has been watching too much CNN.

As dbrowne1 said, their is no law prohibiting the use of a preban mag in a postban gun.

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I don't believe this is true. The reason why most manufacturers only supply 10 rd mags is because that is all that can now be manufactured for civilian use. A manufacturer could buy pre-ban mags, produced before 1994, and package them with their product if they so wished.



Since there is no law prohibiting it, you can't prove it (can't prove a negative). The thing to do is ask the person to prove that it is illegal by citing the specific law. He won't be able to, since there is no law against it.