new guy:

I have a chopper lump Wm. Evans with an invisible seam as well. Takes a lot of magnification and bright light to see it.

Bulldog:

Because the lumps are integral to the tubes of chopper lump barrels, they're theoretically stronger than dovetail lump and shoe-lump barrels, and they're certainly the most expensive. With respect to the lumps, mono-bloc barrels aren't necessarily weaker, as the lumps are integral to the bloc. They're just a cheaper method of barrel-making. Unless they're seamlessly sleeved, they're also very often unsightly due to the joint, and the fact that the barrels often don't take blacking the same as the bloc.
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