Magazine capacity and specialty rounds,ie.458 Socom

[trnorman]

Saw a post earlier and was wondering, if a 10 round AR magazine will hold 3 rounds of 458 Socom, and a 30 round magazine will hold 10 rounds of 458, how does that work within the magazine capacity laws of California. Is the restriction based on the manufacturers specs or the round utilized in the magazine at the time it is inserted into the rifle? If the magazine is capable of holding and functioning with more than 10 rounds of ammo isn't mere possession in CA illegal, regardless of the intended round used?

[elsolo]

possession of a standard cap magazine is not a crime

Most any 10 rd .40 mag will hold 12-15 rds of 9mm, and most guns available in .40 are also available in 9mm, some will even work with the .40 mags stuffed full of 9mm

possession of a 10 rd .40 mag is not illegal

[Quinc]

Welcome to the 458 Socom club!

[Jpach]

People use Pmags as 10rd 458 mags. It isn't their fault that it also fits 30rds of 5.56. Ill just leave it at that .

[trnorman]

possession of a standard cap magazine is not a crime

Most any 10 rd .40 mag will hold 12-15 rds of 9mm, and most guns available in .40 are also available in 9mm, some will even work with the .40 mags stuffed full of 9mm

possession of a 10 rd .40 mag is not illegal

Possession is not, however, importation of a complete mag or assembly of a mag rebuilt kit into a 30 rounder is. Since companies like Magpul mark their magazines 5.56 how would one handle the possible issue with law enforcement that could arise? I could see if the magazines were unmarked for the intended caliber and they were stored with the appropriate rifle.