I sent an email to Ugly Dog Hunting asking if they made a vest with loops for a .410. Dee their reply below. I guess you had better get the sewing kit out
I’m not sure where to find the vest you describe. Most are made with 12 ga loops. He might try tightening the loops by stitching them tighter.
We do not carry a 3x vest in camo.
Ugly Dog Hunting