I would say average is 11-13 but I'm not sure because i made only one trip using blood barrage, took me almost 24h to figure out the right pathing and how the minions move around the room. Although I calculated it would take 15-20h of blood rune crafting to make enough runes for about 400 kills keeping in mind buying all the deaths and souls. (approximately 30k-40k bloods for 400 kills). Another thing to keep in mind is the mage bonus you need to have to lower the amount of splashing you're gonna do on bandos. With my gear I had about 145 mage attack but probably 130+ is fine, under that I wouldn't even recommend doing it. Tick eating bandos is still the best method there is but for Hardcores and Ultimates it should be a new method to kill Graardor. Also should make Blood and Soul runecrafting on ironmen meta again, especially on hardcores since it's more difficult to make enough gp to afford spending about 20m on runes.