I was at the range yesterday and got a first-hand lesson on the effect of crossbow roll on point of impact. Admittedly this was at very long range - 125 yards. I was shooting at the 3D elk at the back of the range and the point of impact (POI) was a good 8-10 inches to the right. When I had set up I had noticed that the table I was shooting from had a mild tilt down to the right. lightbulb So I grabbed something to stick under the right-hand foot of the bipod to roughly level the crossbow... it was maybe 1/8 - 1/4" thick. Bingo, the POI shifted 8-10 inches left and I started dropping them in the 10-ring again. So I'm definitely going to order a bubble level for this thing. The other thing I'm going to do is to see how this effect varies with range. I would assume that at 40 yards the effect of crossbow roll on POI would be much smaller than at 125 yards, but it would be nice to confirm this.