I have shot quite a few deer with the ole 30-30 over the years and have never had one drop in its tracks. All were good shots right behind the shoulders with exits,most all the deer ran at least 50 yds with the furthest running about 175. I would not expect to see a drt result with the 30-30 unless you make a neck/spine or head shot. I myself don't trust the ole marlin's accuracy to do a head shot as the best groups I used to get were about 2 inches at 50yds and 3-4inches at 100yds. Needless to say I don't own a 30-30 for that reason and rely on the 7 RM and the 300 WM for the DRT work, and have had excellent results with those two calibers.
