I had a sxs Ugartechea that had .021 chokes. It was pretty tight patterning. One gun I have has been altered to cylinder bore on the right barrel, so I relieved the forcing cones to about 3" cones and polished them. The gun shoots more evenly dispersed patterns than any other 410 I own. This bore actually holds together for some decently long shots. It's my favorite quail gun. One gun I have with standard cones and full chokes has excessively hot cores in the patterns. My recollection is that Briley calls .020" a full choke in 410. I have one 410 gun that has a .035 choke. It patterns ok.
