you cant without knowing the spreads. RNG and loot tables work this: RNG is just a random number generator, when you beat a boss or trigger a reward event RNG rolls a random number. This random number then makes a call on the "Drop table" for that boss or reward event. A Drop table works as follows: There is a table of rewards say gun 1, gun 2 , piece of armor, and some worthless crap. The drops will be listed on a numbered table, for this example 1-100 1-25= worthless crap. 26-27- gun 1 28-45=wothless crap 46=gun 2 47-75=worthless crap 76-85=piece of armor 86-100= worthless crap. The RNG rolls a random number, but the results are entirely dependant on how the drop tables are populated.