indian artifact hunting help?

ok ive found arrowheads, old musket balls, knives, pottery, spear heads, axe heads, matatees or how ever u spell it, that kind of stuff but i have never found a buffalo skull or old revolver/rifle i have even found a cavalry spur! i live in the texas panhandle and have about 50,000 acres to work with andand it has creeks and flat land mesas and brush all kinds of terrain. so is there anywhere specific i can look to find a buffalo skull my dad has found one but i want to and i have already located indian campsites and i also would like to find an old rifle or such and indian scurmishes did happen on the creek.