Yes you do want both gauges. You'll also need a barrel vise and an action wrench. When I did my 112 to 223 AI, I was surprised how easy it was but be forwarned, hope you have strong arms. A little rosin or powder on the bushings will help for a tight grip. When removing the extractor from the bolt face I put it in a zip lock bag so the detent ball and spring didn't fly away. All in all it's a straight forward process. On a side not I think you'll like the whelen. My 7600 likes 200 gr hornady sst's and btsp's sitting on top of 4064. For larger game I load 225 gr partitions.