RE: Trap Shooters
I shot trap leagues for five years. I prefered a modified choke with 8's, sometimes 9's. If you go with 9's you have to shoot fast. The 8's work great. 7 1/2's are not really needed. I will take extra pellet count any day, unless the clays are hard. One range we shot at had hard clays, so I used 7 1/2's their. Just try a few combos. And the best advice I ever received concerning trap was, "Head down, eyes up." Good luck.
Sorry, I didn't see the yardage. I agree, stick with the full choke if you are shooting from the back. And go 8's at the smallest.