Milt, Green Dot is way too fast burning and high pressure for a gun such as yours. You are better off sticking to a slower powder like Unique and light shot loads to keep the pressure well below 10,000. Green Dot is not a preferred powder in 28 gauge even though it is mentioned in the occasional published load. Those loads are meant for people who just happen to have Green Dot on hand and have a modern 28 gauge gun.