Bill, I've shot a lot of low grade factory .38 factory ammo out of mine with good results, but I don't know how fast they were moving. I've found, in the Maxis I've owned, accuracy wasn't effected that bad with the jump to the rifleing with the .38s. POI is not the same, but I just find it and use Kentucky windage without adjusting the sights. With factory ammo it usually shoots a little high. I suppose I could record the change on the scope and enter it back later. I haven't bothered because the .38s are a playtoy round, not meant for serious work.
Jason, I think loading TB in the Max or Mag cases with 158s would work.
Pete