The Bersa Thunder 32 manual only shows the BT32 with a 10 round mag.
TECHNICAL DATA
Model Thunder 380
Model Thunder 32
Caliber: .380 ACP
System of operation: Semiautomatic
Length: 6.61 inches
Height: 4.92 inches
Width: 1.34 inches
Barrel length: 3.5 inches
Weight: 20 ounces
Rear sight: Notched bar, dovetailed
Front sight: Blade, integral with slide
Magazine capacity: 7 cartridges
Safety features: Firing pin / magazine
Grip: Polymer
Finish: Blue/ Nickel/ Duotone
Caliber: .32 AUTO
Magazine capacity: 10 cartridges
After firing the last cartridge,
the slide remains open
The enclosed picture is of the BT32 mag I have and I loaded it with 9 rounds, I could not put a 10th one in. The metal part of the mag is 3 7/8 in long.
Hope this helps.