The twist rate is actually for a heavier full bore slug, that is why they tend to not shoot the light fast slugs very well. Normally most slug guns with a 1 in 35 inch twist rate tend to shoot 1 ounce slugs around 1500-1800 fps pretty well.

Some of the newer guns are coming out with faster twist rates, I think H&R may have even changed theirs. I know browning uses a faster twist rate.

I believe the rifled barrels and choke tubes were originally designed to extend the distance of existing Foster and full bore lead slugs. Then Sabots started to get popular.

I actually got better groups with some 3 dollar a box fosters than I did with some of the 15 dollar high tech sabot rounds. I just feel the modern the XTP controlled expansion bullets work a bit better on game then lead slugs do. Both will kill deer though.

Paul