Tut, I had to do a little looking. I came up with a 280 20ga with 28" M/F barrels. I'm pretty sure the factory choking would be the same for all their various models. Constrictions were .013 and .025. Since I owned that one, I had a 200E 20ga choked IC/M, and the mod constriction was also .013--so there does appear to be consistency in what they use for a given gauge and choke.