I use a gauge built on the same principle as the Hosford gauge. It is called "Truth Gauge". Used with the barrel in horizontal position. Having used both the upright table model and mine I have far more faith in mine. The flex being discussed is really no concern once proper technique is understood. And with gravity holding the ball firmly against the inner wall there is no error from that. An added bonus is it's highly portable. I always take mine to gun shows and it has saved me from a bad mistake a number of times.
