I heard that the H&R slug guns shoot the SST real well. First thing I would do is do away with that $30 scope and get a better one. I'drecommend the Nikon Pro Staff 2x7x32. I have them on two muzzleloaders and 1 one my 1187 slug gun. I also have a Bushnell Sportsman 1.5x4 on a Mossberg 500 slug gun. Either one is made for shotguns. Then I'd start back with the SST's but try it at about 25 yards and shoot for a group, don't try to zero it in. If the SST's don't shoot tight then try some Lightfield Hybrids. Find out what your gun shoots the best and then move the target back and zero it in. May take a few differnet makes of slugs.