Good read bearhunter. I've heard a lot of folks say that they always shoot 5 shot strings with their hunting rifles and for the life of me I can't figure out why because as you say, they first one is the one that counts. I will often do 3 shot groups out of a cold barrel at the range to get an idea of consistency but with a light weight barrel and fast hunting loads, more than 3 shots often equates to barrel abuse by over heating in my opinion.
I haven't tried shooting groups with my magneto speed attached because I assumed it would change the point of impact but after reading some of the answers here I may just try it for kicks and giggles.