Does anyone know if the Williams "Ace in the Hole" rail with rear sight will fit on a Mossberg 930JM receiver. The rail is made for the mdel 500. Some people told me a standard straight 500 rail will fit on the 930, but the Williams Ace in the Hole looks like the rear part of the rail is turned down to match the countour of the rear of the 500 receiver. Is the countour of the 930 receiver the same as the 500? https://williamsgunsight.com/product/ace-in-the-hole-tactical-mossberg-500/ .