I had the same gun and had good results using both the carlsons 575 and primos tightwad for magblends and federal heavyweight 6&7 shot. I don't believe 40 yds is a problem for either load/choke combo. After being a Hevi user for the last 10 years I am trying the federals in my SBE ii just to see what happens they should be in Thursday to pattern. I may have made a mistake by ordering some of the 3.5 #6 though.... we will see. Best of luck this season.
Here is what has made me look to switch... hopefully the 6's will kill a gobbler or coyote out to 40... I have rolled a bunch of coyotes with lead and hevi and killed turkeys without issue but when Randy wake man says that the 6's penetrated like lead 2's and had the pellet count of lead 5's I want to give them a try.
http://www.randywakeman.com/TheReasonforFederalHeavyweight6forTurkey.htmHevi #7
pellets per ounce: 275
energy - ft lbs per sq inch: 163.4
lead #6
pellets per ounce: 224
energy - ft lbs per sq inch: 166.4
lead #5
pellets per ounce: 173
energy - ft lbs per sq inch: 198.8
Hevi #6
pellets per ounce: 206
energy - ft lbs per sq inch: 198.8
lead #4
pellets per ounce: 136
energy - ft lbs per sq inch: 232.7
Hevi #5
pellets per ounce: 159
energy - ft lbs per sq inch: 236
TSS #9
pellets per ounce: 360
energy - ft lbs per sq inch: 236
Heavyweight #7
pellets per ounce: 220
energy - ft lbs per sq inch: 254.4
Hevi #4
pellets per ounce: 125
energy - ft lbs per sq inch: 274.6
TSS #8
pellets per ounce: 250
energy - ft lbs per sq inch: 293.3
Heavyweight #6
pellets per ounce: 165
energy - ft lbs per sq inch: 303.8
Heavyweight #5
pellets per ounce: 127
energy - ft lbs per sq inch: 355.1
TSS #7
pellets per ounce: 183
energy - ft lbs per sq inch: 355.1 "