Heated in a little back set profile on a deflexed handled BL lately.Only an 1 1/2".If it's like hickory it should hold at least half of it.I partially tillerd this one to 20" before heat treatment.Guess every piece of wood can be different as to holding a heat treatment.I'll find out in a week or so.I wonder if reheat treating BL is kinda risky.I had to hold my heat gun about 5" away and steadily moved along as it did turn darker quicker than say hickory or elm.I did shoot a laser thermometer on it as I progressed and usually run the temperature up to about 400 degrees F for at least a minute before moving along.