Browning and bottom barrel light strikes are a known thing. Nothing to do with the ammunition as you found out. A very large number of shotgun shells are loaded with Cheddite primers as most smaller shotgun shell manufacturers don't make primers. And even some of the biggest manufacturers outsource primed Cheddite hulls for their bottom of the barrel promo loads.
But 100% Browning is known to have bottom barrel firing issues.
But 100% Browning is known to have bottom barrel firing issues.