Weapons effects not matching hits?

[II/JG54_Emil]

This is a long known "problem".
And it is a FC99 says a multifactorial "problem".
It´s depending on whether you are online/offline, on the damage model the weapons characteristics, selective memories.

I the described situation -LaFN vs 109- it´s all of them.

In the addressed problem of the gunpower or effectiveness, historically a Mk108 should need 1,046 hits on a average fighter to down it.
Down it means the plane is so badly damaged that either the pilots ditches/crashes, bails or is killed.

The historical average MG151/20mm hits necessary to down a fighter are 4, stated by the Luftwaffe.