Correct, but of course at the expense of number of pellet strikes.
Shot size selection requires finding a workable balance for both the game and the range.
The 'style' of shooting must be considered also.
Brits are very fond of their #6 at 270/oz, but that's generally used for high elevation 'driven' shooting. We have a very good simulation of that here and I can attest to the effectiveness of that classic load when the birds show their underside to the gun.
That equates to about a US #7, and I really would hesitate before an up the tailpipe shot at a tough old rooster... unless of course the elusive 'perfect point and flush' could be achieved and the hammer dropped at 25 yards.
When I'm using a 12ga--especially short-chambered--Gamebore's "Pure Gold" load of 1 1/16 oz Brit 6's (essentially the same pellet count as 1 1/4 oz US 6) is what I'll use in the R barrel. Very effective on our "walked up" wild roosters over dogs. But then a 40 yard shot is unusually long for me. And if I'm presented with a longer opportunity, I'll do as Dave Erickson suggests and select the rear trigger. The L barrel has a 1 1/8 oz load US 6's through a tighter choke, reloading formula that yields 1150 fps at about 7,000 psi, so pretty gentle in old doubles.
