8 and 8.5 are excellent choices for the .410. The harder the shot, the more round, the better. Your result may be different than mine, but velocities above 1300 fps do not work well for me. Those 3/4 ounce 3" .410 loads are about 1150 fps and I expect they pattern well. We use to say too much velocity would blow a pattern. Maybe you could do better with higher velocities with other than IM or Full chokes. I try to find sweet spots with loads, chokes and style of shooting. I no longer have the reactions for strict swing through shooting style. Sustained lead shooting style never seemed to work well for me with the .410. Too much measuring and then failing to continue the lead needed. In fact I often say the more you think while shooting a .410 the less great results seem to occur. Short, quick shooting seems to work best for me. Think it, see it and shoot it.
