Also, it should be remembered that Oswald?s revolver was pretty low powered. It had been re-bored for slightly larger ammunition, but Oswald used the standard ammunition. So, a lot of the gas went around the bullet and the bullet had a slower than typical speed for a handgun bullet.
As I recall, one bullet barely penetrated the skin and travelled around Tippit?s body, not straight across.
Would such bullet produce less back-splash? I don?t know. But it sounds possible.
And do we know how close Oswald was when he fired the final shot?
Maybe that is why he went into the shoe store.