Check out the 12 gauge From Hell threads. Similar loading is being done using 20, 12, 10 and 8 and now 16 bore 2 3/4" plastic on up to 3 1/2" brass cases with slow-burning powders and a variety of actions. I suggest you contact the author of that thread Ed Hubel. This link will get you the 10 page. http://forums.nitroexpress.com/showflat....true#Post121088