As the bolt goes back the mag cycles then the pellet drops back onto the probe and possibly jamming it... I'm still not sure how it can get inside the action, I'm not saying your wrong villaman I'm just trying to see how it can happen... And your right, you should not have to do it to a new mag but if the gun fits then why not? My point is you either want to shoot the gun or not and as manufacturers all seem not to care then why not buy 2nd hand & sort the issues?
Rhys