So yesterday I was at training with my department for patrol rifle. We were using our personally owned firearms and had finished training and were in the process of shooting a qual. We began the qualification at the 50 yard line where we fired four rounds.My first shot fired, but the rifle did not cycle completely.I cleared the malfunction by stripping the magazine and running the bolt a couple times, then replaced the magazine and fired the next three rounds without incident.We then moved to the 25 yard line and began the course of fire there.During that course of fire, I did not notice any malfunction prior to hearing a loud explosion, feeling gasses against my left wrist near the magazine well and feeling more recoil than usual.I began to do a malfunction clearance but then realized my magazine was missing from the rifle.I then looked at the rifle and saw that the upper receiver near the ejection port was swollen.

I inspected the rifle and found that the upper receiver had split at the ejection port as well as being pushed out.The dust cover was also arched.I could see the bolt carrier about an inch back from the forward position.I could see the extractor was pushed out from its normal position.Looking in the magazine well, I could see the bottom portion of the bolt carrier had split down from the main portion of the carrier.The forward assist was cracked.We retrieved the P-Mag and the front lip was visibly melted.I received no noticeable injury from the explosion other than some mild power burns on the inside of my left wrist.

I left the firing line to collect my things and take photos of my rifle.While I was taking photos, another Officer came back to the table and advised me that his rifle had done the same thing just a little while after mine had exploded.

My rifle was a Rock River Arms LAR-15. I bought it new two years ago and have put about 2000 rounds through it. The only problems I had with the gun during that time were from mag issues, either not being inserted all the way or on my USGI mags with the lips spreading and causing jams. The other rifle was a brand new Bushmaster with only about 80 rounds through it at the time. We were using Remington Premier Match 62 GR. HP (MATCH) R223R6 ammunition provided by the training staff.The lot number on the case was H16 NAI.This was the duty ammunition that we were going to use to qualify.

The rifles are being hand delivered to Remington next week for them to inspect and see what happened. We are hoping it is just a bad lot of ammo. We were told that they would make things right with us so we will see what comes from it.