A couple of accidents are known to have occurred in the past 18 years.

One was the fatality of a N.J. man at a Shooting Club Range in Pennsylvania. IIRC - a dangerous overload or detonation was initially suspected. The Winchester-Lee Action shattered and a piece of metal was driven into the Shooter's brain.
Victim was Glenn deRuiter and the accident occurred June 29, 2002.

Update - (The cartridge cases were altered from .30-40 Brass, per 'Forgotten Weapons', and Glenn was known as a careful reloader.
This opens the possibility this tragic accident also may have been due to cartridge case failure).

A more recent accident likely involved Case Failure. The 6mm (.236 USN) Cartridge Cases were made from converted .30-40 Krag Brass.

The case rim was removed and an extractor groove was cut into the cases by machining the case-heads on a lathe.

The owner/shooter posted pictures on a gun forum. It appeared one of the cases failed at the extractor groove, allowing high pressure gases to split the action & stock and detach the barrel. The bolt jammed and held, to a degree.

The owner received relatively minor injuries: a bruise in the middle of the forehead, two black eyes, ringing ears, and a ruined Winchester.