A lot of the criticism of the LRN bullet were deserved but it wasn't the bullet per se that was the problem. Weak loads, poorly regulated guns, poor marksmanship and the dress of most people back then consisted of heavy layers of clothing. 38 was used because like the 9 today it was cheap ammo and the guns were plentiful and cheap to buy in bulk. Besides without knowing where the 50% number came from I bet it was referring to fight stopper, not kills.
No mention of number of rounds this chart is bases on but still interesting numbers.
As for me I have used LRN in a carry gun but now that I have a choice I make mine LSWC and make it larger than a 22.
It is also why when there is a bump in the night at dark thirty I answer the call with a flash light and a shotgun.