Question about magazines.

[budprop]

I recently purchased a couple of magazines online for my Sig P229 in .40. The mags I purchased were advertised "10 round .40 S&W". I received them and they are marked to 13 rounds. I immediately contacted the seller and he responded that they are 9mm mags that hold 13 rounds of 9mm, but only hold 10 rounds of .40. I confirmed this and they only hold 10 rounds of .40. I disassembled them and sent them to family in Arizona while I try and figure out what to do with them. I don't have a 9mm Sig and the magazine and feed lip dimensions are almost identical to the 10 round Sig magazines.
Here is the question. Are these magazines legal for me to run with my .40? I wouldn't use them for self defense, just for target practice so please don't let this turn into a "don't use 9mm mags in .40 guns".

[bigdawg86]

Your fine. You purchased magazines advertised for ten rounds and they hold ten rounds. Just like the 50 beowulf uses standard 30 round GI mags but only holds ten. So go ahead and get the mags out of your closet named "family in Arizona" and carry on.

[rromeo]

If they truly were large capacitt magazines, they were legal to have until you disassembled yhem and sent to your family in Arizona.