Howdy folks. This happened back in August but I’m just now posting it here. The full thread on SASS.net can be found here
August 22, 2015
I just had my primer tray ignite in my Lee Loadmaster press. I had just filled it so there were between 75-100 Federal Large Pistol primers in it.
All I heard was the blast and I saw a flash. The primer assembly was blown into pieces and since my shop is pretty cluttered, I’ll probably be finding pieces for a while.
I did have the Lee blast shield installed and it worked, it is now pointing straight up and is quite misshapen from the blast. I had one small piece of plastic stuck to my forehead but other than that I don’t think anything hit me.
I’m not finding a lot of primers but every one I’ve found is just an empty shell…I’m guessing that they all went off.
After this experience I’ll be wearing a face shield and earplugs when I reload….my hearing taking the brunt of the after effects.
No more reloading until I get a new blast shield, primer tray and primer assembly.
What fun! 
Below, the remnants of the primer assembly which was below the shell plate…which is why so much of it is intact. The offending primer is there also, looks like it was offset when inserted.
The blast shield blown straight up and deformed.
Here’s what I got back from my inquiry to Lee. They did replace all the parts free of charge.
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Hi Bill,
During our primer testing, Federals can explode with sufficient force to seriously injure the user, or persons nearby. Only CCI and Remington are safe to use with our Progressive presses.
If you wish to stick to Federal primers, I would recommend our Classic Turret Press # 90064 and Safety Prime # 90997.
Sincerely,
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I did change presses, bought a Dillon XL650
Willy