I don't know if it is possible for the 12 ga or even 16 ga. The 20 ga looks to be about the largest for which this could be accomplished in this size die. I wish someone made a .410 die in that size. Iit would be ideal for us single shot users. I'm assuming demand would be too low for the gauges in which it could be done, to make it worth marketing. We can only wish.
