I shoot 1 oz. reloads at practice and 1 1/8 oz. factory shells for registered. Not sure why I shoot the 1 1/8 ...same scores with both, but thats what I do. IMO, from the 16, there is ZERO difference as long as you shoot a IM choke or tighter. Pattern board tell me the same thing.
Harlan, said-why would you enter a 100 target event & shoot 12 less shells. That is the equivalent in shell loss between 11/8 oz & 1 oz.--I'm as recoil sensitive as anyone, if I'm competitive in an event I'll stick with 11/8.
I shoot 1oz #8 for singles and doubles, and an occasional round of caps. My standard caps load is 1 1/8oz #7 1/2 @ 1145fps.
If I shoot 300 or 400 1 1/8oz loads in a day, my shoulder is sore the next day and I'm paying more attention to it than to my shooting, and my second day scores show it.
I should mention that I sent my unsingle barrel to Kerry Allor and had him turn it into a dedicated 27 yard handicap barrel. For singles, I honestly cannot tell the difference in most breaks between 7/8, 1 and 1 1/8oz loads with this barrel.
I started shooting 1-1/8 oz loads and had a friend (God Rest HIs Soul) give some 1 oz #9 shot shells and they worked good. I have since gone to 1 oz 81/2 shot and now crush the birds on the 16 yd line and first shot in doubles.