You will almost certainly need the faster twist heavy liner, and I dont think you would be happy with the speeds. There is a small BC advantage, but due to the slower starting speed I dont think I would bother in a Maverick (at least as stock). You would have better performance with the 34.9 or 38.5 grain. You can push them faster easier and the result will be flatter trajectory and more speed at the target. As mentioned those wont fit in any magazines, not even the STUD mags. I think the real heavy slugs are better suited for something like an AirForce or Vulcan 3 or maybe a Panthera.