I made a 48x48 "oops I missed the store bought target" backstop to go behind my actual bag target to save my fence in the event of a really errant shot. I put two layers of outdoor carpet on the front of a cardboard box full of cardboard and other stuff I shoved into it. It stops arrows from my 50 lbs draw compound bow just barely, but the arrows are VERY hard to pull out of the carpet. I wouldn't want to shoot it all the time on purpose. Too much of a pain to remove the arrows. I only shot it to test it.
It would last a bit longer and the arrows wouldn't penetrate as deeply if you had it hanging while you shot it, instead of having it laying against a backstop.
Well as thick as it is I built one that was similar to this that was 18in thick with cardboard and slats of carpet in between and I tell you one thing at 40 yards at 370 feet per second it went through that 18 in of cardboard with carpet and still went into a 12in styrofoam archery target so I would put my compound crossbow up against that challenge any day of the week
