Wolff, .380 Walther PP 16 lb recoil spring .
It arrived last week and I tested it last weekend. I used 3 magazines , 8 rounds each.
One magazine loaded with Geco 73 grains FMJ, one loaded with Sellier & Bellot 73 grains FMJ and the last magazine loaded with
Geco and Sellier & Bellot , mixed.
Not a single malfunction, of any kind, occurred