You may want to consider Hartin crimping. Start with a once-fired hull--I use AA's. You will cut them off to 2 1/2" and load like you did before EXCEPT the last step is to place a card wad over the shot to hold everything in. It looks a little like a rolled crimp. I am using these in a 1st yr Model 12 with a short ejection port and chamber and they work fine. E-mail if you want more details. But I would definitely use a low pressure load in a 20 ga Flues, even more important that the length of the shell. Quailman85749@hotmail(dot)com
