Well I bought a hesse lower awhile back and it ran great until I put a car stock on it. I was shooting it and after about 200 rounds the bolt carrier stopped moving freely. So I did a visual and could clearly see the buffer tube had worked its way slightly upward(12 o'clock). Took the buffer tube off and could see where the bottom portion of the buffer tube threads were getting shredded.
Im thinking the added shock from the lighter buffer coupled with the sharper threads on the car buffer tube caused the deterioration. The A2 stock ran with no problems ever after I put it back on after having problems with the car stock.
So what I did was make an aluminum plate about a half inch thick to bolt on to the back to give the tube more support. I ID of the plate is only about .001 bigger than the tube so its a nice snug fit. I drilled and tapped two 10-24 holes in the back of the plastic receiver to be used for mounting the support plate. The idea is the tube cannot tilt up or down and remains true to the receiver.
If I had been thinking I would have made a special buffer tube nut that once torqued down, could be screwed to the support plate making the tube even more stable as it would divide the recoil to both the buffer tube threads and the support plate. I will work on that next.
Its worked so far with about 100 rounds through it. I'll put a couple hundred more into her tomorrow.