I have two Bersa Thunder 380 cc's. One of them with out a mag in it will not stay in the locked side back position. When I engage the slide lock manually in the rear position it will not hold. At the range when I'm firing, after emptying a mag, it will stay in the locked rear position, until i drop the mag to put another in, then it will move forward. If anyone can chime in on this, it would be appreciated. Also if I interchange slides, both will stay in the rear locked position when engaging the rear locked slide position.