The Star progressive is based on a machine patented by Winchester in the 1890's. Ellord Mott essentially copied this machine and scaled it down. Ellord's original patent was for a machine to load rifle, pistol and shotgun shells. As far as I know no shotgun presses were ever made.
The Star appeared somewhere around 1930. Originally they had primer tube explosions. Ellord redesigned the Star primer tube to withstand the blast. A Star primer tube is actually a primer tube/primer shield. Dillon, decades later, made a big deal about putting his weak primer tube in a separate primer shield. Good advertising but not an original idea. Ellord helped Mike Dillon design his first produce, the Super Star kit used to convert a Star pistol machine into a unit that could load 223 rounds.
Do Star's blow up primer tubes. Sure. What's the primary reason? Operator stupidity. The Star primer mechanism was, in my opinion, the best ever made. Only the current RCBS primer strip system is more reliable. Why then would Star primer systems explode? Because many operators can not leave well enough alone.
Ellord personally hand assembled every single Star ever shipped from the 1930's to somewhere in the 1980's. They simply worked. Some fools, however, took them apart and, well, messed them up. That can cause a problem.
Any mechanical device can fail BUT Star progressive primer systems are among the most reliable devices made. I'm absolutely positive about that. I probably owned nearly a dozen including a straightline star progressive. I've also owned and at least tried to use maybe two dozen other progressives.
Another possible source of trouble with a Star priming system is the use of primer turrets. Anyone dump enough to do that deserves what is going to happen to him. Evolution in high gear.
A well adjusted Star or one whose factory primer system has NOT been "improved" is as good as this gets. The description you provided, multiple explosions, indicates that these people weren't all that high up on the evolutionary ladder.
