I believe that there is a wide range of acceptable accuracy with carbines. I believe that some will shoot pretty good 1-2" groups at 100 yds, but far more are in the 2-4" range.
Here's my best shooter a NPM with IBM barrel. The 9 ring hit is my bad shooting. This at 100 yds using reloads w/Rem FMJ. The SR-1 has a 3 1/4" 10 ring, so Jim's shooting would easily hold the 10 ring on an SR-1. People should really give their carbines a workout at 100 yds. I'd bet that after some practice they could surprise themselves. I think that the sights, trigger and light weight just make people think that they can't shoot well. And yes, I can't see squat either.