RE: xtrema shoots to the left?
Could also be the choke. I have an Extrema 2 and it shoots straight, but mine also shot to the left when I patterned it with a Primos Jellyhead choke. I got my friends to shoot it and it shot left with them as well. We went as far as putting that jellyhead in my friends benelli and it shot crooked out of that gun as well. My gun shoots straight with every other choke that I have put in it. Just something for you to check out.