On technical level, there are 4 stats and 10 possible values for each of them (range between 65 and 200). You start with one roll or "one line" and you can will get up to five when you reroll stats. Each time you reroll it picks 1 stat and value for each line, and same stat/value can be picked multiple times for different lines. This means you can get up to 1000 substats and all can all be the same substat, but it's 5 times more likely to win in lottery than get it, but if you get 700+ you already have more than Savage weapons.