The Krag receiver wrench from Numrich will clear the military front sight base, not sure about the aftermarket or other non-Krag front sights used on Sporters. If you had a real tall sight blade you may have to remove the blade but you would anyway to get the upper band on.
The lug does all the work. The hole for the receiver ring is slightly oversize which allows a layer of tape around the ring to protect the finish. The shortcoming is there is no good way to attach a breaker bar in the shallow slot provided. I believe most use a large wrench on the body of the receiver wrench to do the job.
I don't have the wrench on Ebay with the aluminum inserts but I do have the vise he sells and it works very well. The aluminum collar for the barrel vise will not fit over the front sight base once the barrel has been installed though. Split the aluminum collar into two pieces before you clamp the barrel and it works fine.