I brought home a two tone sig p226 yesterday and tested it out today. The first 30 rounds went great, then about 2 to 3 round out of every 15,I would have either a light primer strike or the pin would not strike the primers at all. When that would happen i would drop the mag, remove the round manually and load it back into the mag and it would fire.The slide also stopped locking back when the mag ran dry. Anybody know what could be causin this? The man i got it from only shot 16 rounds threw it and put it away if that matters.