Messy lua

function RSGMod()
    local rsg = {}
    local index = 1

    --Determine weapon
    local wepIndex = RSWeaponPacks[math.random(#RSWeaponPacks)]
    rsg[index] = RSWeaponPacks[wepIndex].weapon[1]
    index = index + 1

    --Add ammo
    if RSWeaponPacks[wepIndex].ammo ~= {} then
        for i=1, math.random(RSWeaponPacks[wepIndex].ammo[2]) do
            rsg[index] = RSWeaponPacks[wepIndex].ammo[1]
            index = index + 1
        end
    end

    --Add Bomb items
    local expIndex = RSExplosivePacks[math.random(#RSExplosivePacks)]
    local expNum = math.random(RSExplosivePacks[expIndex].number)
    for i=1, expNum do
        rsg[index] = RSExplosivePacks[expIndex].item[1]
        index = index + 1
    end

    --Determine Rare items
    local luckRoll = math.random()
    if luckRoll < 0.25 then --25% chance for extra item
        if luckRoll < 0.05 then --5% chance for rarer item
            local URIndex = math.random(#RSUltraRare)
            for i=1, #RSUltraRare[URIndex]
                rsg[index] = RSUltraRare[URIndex][i]
                index = index + 1
            end
        else
            local RIndex = math.random(#RSBonusPacks)
            for i=1, #RSBonusPacks[RIndex] do
                rsg[index] = RSBonusPacks[RIndex][i]
                index = index + 1
            end
        end
    end

    return rsg
end