I have upwards of 50,000 rounds loaded on my 550B and the only squib I've ever had was a factory loaded round.

The problem isn't a progressive press it's the nut operating it.

1) Put a light on the head of your progressive press. Several companies sell them for various progressive presses.

2) Visually inspect the powder level in every case before you seat a bullet on it.

3) If anything - ANYTHING - happens on the press that is out of the ordinary, stop and check each station on the press before pulling the handle again.

4) If you get distracted at any time - stop and check each station on the press before pulling the handle again.