The 7 and 9 round magazines are interchangeable.
BERSA manufactures both 7 and 9 round mags, primarily in blued or nickel finishes. Plain old
marketing strategy dictates how the mags are 'bundled' with the particular Thunder 380 finishes. Marketing strategy changes from one country to the next: in the Philippines, Bersa Thunder 380's of any finish are bundled with a pair of 9-round mags --my nickel Bersa (seen in the clickable pic below) is one such.
In the US, all Thunder 380's are apparently sold with just one 7-round mag, save for the Deluxe. While the
Thunder 380 Deluxe may be a
normal Thunder 380 with a custom rollmark and a better finish, simply bundled with a 9 round mag...
There is still potential for confusion with the
Bersa Thunder 380 Super.
That would be a different animal, featuring a steel (rather than aluminum) frame, and a
wide grip to accomodate a double-stack 15 round mag that is NOT interchangeable with the single-stackers of the normal Thunder 380's. The Super has apparently not proven too popular, and I think it was originally targetted at the East European LEO market. ---maybe for that much weight and thickness, it makes more sense to pack a small 9mm or even a .40 ....but I am wandering astray now.
hth,
horge
PS: Generally, firearms and parts are more expensive here than there in the US, but it seems that for the BERSA, the reverse is true, and particularly so for magazines ---if the online prices for add'l mags are any indication. I'm even happier with my purchase now. My Nickel Thunder 380 with a pair of nickel 9 round mags included, all for US about $330 doesn't come out too badly after all.