I have a Belgium guild double in 10-Magnum that readily digests those monster loads w/o a quibble. It's not fancy but it is very effective in the duck marsh (and at tenderizing my shoulder). I'm fairly certain that your Dumolin is on par with any Best gun, even the British ones. I'm not saying that all Belgium guns were or are poorly constructed, just that during the time period being discussed (near the turn of the last century) a large number of low-grade weapons were sourced from Belgium for export to America. Perception being reality for most folks (then as is now) all Damascus guns were lumped together as being unsafe to shoot with modern nitro powders. It was damned-effective marketing too, because that assertion is still believed w/o question to this day by many otherwise rational folks.
Bottom line is this: enduring quality is never cheap. A well-made gun was expensive in 1901, as they are today. A poorly made gun (or anything else) doesn't improve with age. The trick is knowing the difference.