I have this story 3rd hand, it’s all I know about it, posting as a safety caution.

Club member was loading using a Redding BR3, charge was 11 grs of 4227.  Had a primer spill and could not account for all the primers. Went on loading.  Measure charge handle hangs up. He whacks it harder and Boom.  Measure explodes flying shrapnel hits him. It’s a pretty good injury will recover but have some scars. 

Speculation is a primer found its way into the powder and caused the hang. Not hard to imagine what kind of pressure  caused the measure to come apart.  Powder in the measure chamber no different than in a cartridge case. Ignition and wham.

We all need to be careful.

Boats

That's a very good reminder of how cautious we need to be during the reloading process we do. I've never had any accidents that scared me, but I did have a situation many decades ago when I was showing a friend how to begin reloading his own ammo. During the training process, I lost track of what I was doing, while trying to explain each step. I ended up putting too large a powder charge when I mixed up two different powder charge data for his .41 Magnum cartridge.
Fortunately I was looking into all the charged cases before seating bullets, and it just didn't look right. I dumped a charge back on the scale, and it checked exactly what I set it for. Then I looked back at the manual and realized I'd chosen the wrong charge for the powder. It was not only embarrassing, but gave me a sick feeling knowing I came close to handing him a couple boxes of loaded ammo that could have hurt him.
When I help someone get into reloading now, I make sure if I get distracted with questions, or anything else, I go back and go over everything I've done from the beginning again, so there's no chance of an error from being distracted.

Boats,

A good safety caution.
Was taught that some things shouldn't be forced...  if more pressure than usual is required, something's not right and it's time to back off and make a close inspection.
Hope the club member will recover quickly.

Boats,  AAA and the shoot master told us about it at the shoot today,   by the way Anthony shot his second 40 taday,  got to watch him set off the last shot...  damm fine shooter...M

If the lid was on the powder reservoir I have difficulty imagining how a primer got inside the measure to create the problem.
 
From the beginning, close to 50 years ago now,  I was taught to ALWAYS keep powder containers closed unless actually transferring powder from one to another, and in those cases to recap immediately and to conduct no other activity while the containers were uncapped.

colo native wrote on Dec 20^th, 2014 at 9:27pm:

Second 40 shooting what at what?

Never say never on the accident. One reason I like the single primer priming tool. Sit at my desk and prime with nothing else near by and the one primer in the tool at least a foot from the others in the dish.

by the way Anthony shot his second 40 taday...M

Second 40 shooting what at what?
Its a Rim Ram bash that Boats was involved in,   Quite fun, and  challenging for old timers like me... Anthony used a CPA and his dad shot a 39 I think,  both are gentlemen shooters...fine folkx...

I'm call'n, "urban-legend(in the making)" here.
1-How in heck, did a primer get INSIDE a powder measure?
2-Was there no LID on this PM?
Been load'n ammo for 48+ years-NEVER heard of a primer INSIDE the p'measure. 
LG