If we can get this back on track...
I have used a Saiga 12 (before and after the AK style pistol grip conversion), a Remington 870 Tactical (with the Knoxx SpecOps stock), and a Remington 1100. The 1100 was first, and my scores went up a bit when I went to the 870, but fit still wasn't perfect. The S12 worked fine, but still wasn't ideal. You should have seen the looks I got with the 870 and the Saiga though...
I currently use a Remington 105 CTi II, and the thing shoots like it's radar guided. No straight yet, but it fits me well and it's been 100% reliable. I just need to get more practice.