The barrel vibrations are a infinitesimal factor in the accuracy of a handgun. Virtually every other conceivable factor dwarfs the barrels vibrations into irrelevance.
VarmintAl has a very detailed analysis of barrel vibrations. He certainly doesn't conclude that there is no affect.
He specifically mentions 1.1milliseconds (.0011) as the time that the bullets would exit assuming constant acceleration and ignoring the time from primer ignition to bullet movement. (Neither of which matches real life)
His example, a 22" 416 stainless 30-06 barrel firing a 150gr GK bullet at approximately 3,300 fps says that the bullet exit time is .0025 seconds and almost exactly matches the barrels first upward swing.
Whether or not the receiver is counted as part of the length that the shockwave travels, something that would only happen with an EXTREMELY solid and tight barrel/receiver fit that you'd never see in a factory gun, the shockwave still has time to make at least 3 trips before the bullet exits.
Still happily answering to the call-sign Peetza.
The problem, as you so eloquently put it, is choice.
He is no fool who gives what he can not keep to gain what he can not lose.
-Jim Eliott, paraphrasing Philip Henry.