This Lee rifle obviously did . . . given that the brass of the only previous expended round had flowed into the extractor area. And the receiver couldn't take it.
Couple of additional warnings for those who, like me, load for and fire old military rifles:
1. Get a headspace gauge, and USE IT! "Go" and "NoGo" both. The .303 Lee Enfield is notorious for headspace problems.
2. Work your loads up gradually. Don't go over middle range recommended loads in any old rifle, especially unusual rounds for which you have old data.
3. At the first sign of excess pressure (backed out primer, flowed brass, sticky case) STOP! Please!
Prayers for this poor man and his family and friends. Remember, guys, all it takes is one mistake or a moment of carelessness. . . . be safe!