Davoh, If at all possible I would recommend getting yourself three large excelsior bales. (furniture filling) Your local archery shop should be able to tell you where to get some. They are inexpensive (25$ apiece) and will last you several years ( I gaurantee it!!!) as long as you put a roof over them. Absolutely no pass throughs. You might get eight inches of penetration with the baddest bow out there. (Like my Trykon Ha-Ha) Tighten them down with a couple pieces of all thread and you're good to go. This is just asuggestion, but I gaurantee you will not be dissapointed whatsoever.