Spoke with local PD LT who advised of possble bad batch of Ultra Max .223 ammo.  They had 3 guns develope problems during recent rifle class.  Ammo apparently had a high primer which caused a slam fire.  Magazines were blown out the bottom of the reciever and bolt was damaged or locked up where they couldnt open the rifle.
Might check your ammo for the lot number and check with Ultra Max to see if you have a suspect box.
Hope this helps you guys..  

Would it be possible for you to talk to that LT again and see if he could find out what lot # it was they were using ?

Thanks for any more help.

i have been saying this for a long time,

Is there such a thing as a good batch.