I have found the Shotgun Combo Gauge one of the best purchases I have made. It makes measuring LOP and DAC/DAH a snap, and I think is perfectly accurate. You can even use it to estimate cast, albeit not with the same precision as the other measurements. Well worth in in my opinion.

On the other hand, I see the Bore Gauge as a gimmick, and not nearly so useful as the traditional dial barrel readers as made by CSP and Galazan. They are far more versatile and I suspect more accurate. I wouldn't buy the Bore Gauge.

Keith