I checked 2 Ammo maker sites. They say 3" .410 slugs retain about 425 ft lbs of energy at 50 yds. That's nowhere close to what is recommended for deer.

Like I said before, I would use one if IHAD to, at basically bowhunting ranges, if the gun was accurate.

Since I'm in a shotgun area, I'd consider getting a new lever action .410 made by Marlin or Winchester if they could boost the performance. Maybe a sabot round with a .357 bullet, or something like that.