I recently acquired a 590A1 Blackwater edition with the ghost ring sight system by XS (XS Sight Systems - Sights) Anyway, upon taking it out to the range to shoot some slugs I found myself having to raise my rear aperture to it's near maximum height on the post. Front sight is a .380" from top of sight to bottom of dovetail. I've looked and I can't locate any 3/8" sights that are lower. it appears very odd that the sight would be so high. Stats: I was shooting at 50 yards. Top of front post was center of rear aperture. When I stretched it to 100 yards front post was at top of aperture which is normal. 1oz slugs 2-3/4". 8" pattern@50, 12" pattern@100 Shooting wasn't off, it just made me very nervous that the rear was so darn high to bring the shotgun to a zero at 50 yards. Like being held by the set screws by maybe 3-4 threads. These do not come with protector wings like most rear posts... another thing that has me curious. Edit: Because I NEVER give up. I have been searching and I came up with this product: http://www.midwayusa.com/product/12...ght-340-width-steel-blue-3-32-fiber-optic-red My current base is .340" wide. and overall height is the .380" So by logic I could pick up this one thats .250" tall, shaving a LOT of height off the rear aperture. I'm still searching, so any input would be great. I don't think it's "Human error" right now. The person I got it from could have swapped stuff around not knowing, as the shotgun was new in box when I got it.