Tests, reading forum, confirming information by tests and actual in game experience.
Silent death was popular once with plasma grenades, i assume you know that. I realized sneakers never did a bypass on 10 luck characters, also a developer that makes this game showed a chart where it's clearly shown that with 10 luck it's 0%. Now why are you trying to force unconfirmed info as some truth? Have doubts? I assure you, you can go clear them with making simple tests that the chance to get bypassed is none existent with a character that has 10 luck, that is only for torso shots, for all other body parts it's different because characters with 10 luck get bypassed in all other body parts, values shown in the charts are equivalent to what it's in game.
I'll be damned.
But critbursters all have spray and pray.
Even if you decrease the frequency of the bypasses, gatling laser will surely instakill everyone with bypass and likely will 3brd avenger and m60 aswell. It'd be better for gameplay to get rid of instakills, no matter how rare they are.
There is critical chance modifier and critical power modifier, as far as i know spray and pray reduces only chance modifier.
The values i suggested make it possible to gain close to an immunity from bypasses, you invest points into luck and profit, choices and consequences(6 luck for immunity, just like the same requirement for perks previous session). No matter if it's a bypass from gatling gun, minigun, light support weapon, m60 that's going to be an insta-kill.
As i said, remove bypass protection from luck entirely = new dump-stat, no consequences. Is that supposed to be better?