Not sure what your bag looks like. In my home gym I have a 100 lb double end bag. Top has two chains with heavy straps holding both ends. They are hung on a ceiling swivel hook held by a large bolt drilled into a 4X6 board above the ceiling sheet rock, and the board is braced over 4 roof beams. I can actually swing my body on the bag and I weigh 220 lbs. The other end can be secured to the floor by straps to weights to hold the bag in one place.
Just to give you an idea. Don't be shy about over doing it with bolts, braces and securing something. One poor fellow I know put his bag on a simple hook screwed into a roof 2X4. It came crashing down after a short work out.