I'm sure it's just my sample size skewing my observations.
Guys take a death grip on their forend, pulling the shotgun rearward strongly into their shoulder pocket like a rifle. (Reefing) Then Twist the gun to stack the beads. And then set off a firecracker load for maximum recoil.
It results in a magnified set of forces fore and aft on the lug.
On soft soldered lugs they slowly hinge loose.
I'm sure someone will be along shortly to say that is bs.
But, for me, having seen it happen many times, I started looking at the why, and the rigid shooting style popped up as a pattern.
Since there are millions of shotguns that don't come loose, maybe you need a poorly soldered lug, AND a forend reefing shooting style to tear one loose.
Big guy, small gun, reef, then field loads. Bad recipe.
