Possibly some barrels it changes group size, some it doesn't depends on gun and barrel. The shorter and thicker the less the effects. With hunting tappered barrel im going to say pipe dream.I have a question to all of you that have any version. I got one for Christmas and have not had a chance to use it yet. I have standard hunting rifle barrels that are tapered and waiting for the tapered mounts or shims to install on my rifles. My question is, I was hoping to use the V3 to work up load data, but herd that it will change impacts with it on the barrel. I don't care if they are not zeroed as long as I can trust the group size will not change with the unit off the rifle. I thought it would be nice to see the velocity, SD, and ES as well as the group for each group I am testing at the time. Will it work or is it just a pipe dream of mine.