You could try fireforming 9.3 x 74 brass, the case will be almost as long as a fired 3 in. 410. Could the mis fire been from chamber slop? I tried the 9.3 x74 in my contender, I just could not find a suitable wad, as you gain case capacity over the 410 because of the increase in diameter of the fireformed brass being sized to 45 diameter and also probably because the brass is thinner than the 410 plastic. If there was a .45 plastic wad that would be long it may have been good. Even the 410 wads are not long enough for a 3in case to get all the shot in and too small in diameter, for the case when fireformed to the 45 diameter chamber. Like to hear of different tries to get all you can from a 410 handgun. You may have better luck one the cases are sized to your chamber from the first or second firing.