The TGT-12S is mainly for 1oz. std target loads containing 17-18 gr.of Red Dot /Clays etc. It is used in the nitro 27 for 1 1/8th because the base of the wad is slightly higher than the fig 8 wad. The Nitro 27 uses a much denser powder, Tightgroup -18.5 gr, ( I use a PW J-1 bushing with Red Dot, which drops approx 17.6 gr, the same bushing with Tightgroup would drop around 30 gr or so. I had to modify a C bushing to drop 18.5 ) which if used with a fig 8 wads would yield a concave crimp since the wad isn't up as high in the hull. The opposite is true with the 7/8th oz loads, which calls for 21 gr or so of Red Dot. I load all three of these with the TGT-12S and they work well. Hope this makes sense. Bob