i do prefer the grizzly rods over the range rods to help dial in either side of the barrel.
i use the largest bushing that will freely fit in the bore to keep it from falling in the grooves as the barrel turns. at the chamber end i set the barrel up so the spider adjustment screws are where the reamer pilot bushing will end up when the chamber is at full depth. i start out by adjusting the od of the barrel at both ends to about .001" by hand tightening the adjustment screws on the spiders. i then start with the grizzly rod bushing where the reamer pilot will end up (directly under the spider adjustment screws). i get that dialed in to within a couple tenths. i then move the rod in the bore about 2" forward and dial it in to within a couple tenths using the rear spider. then it's back to the first location and dialed in to within a tenth and 2" forward the same. this may take a few times of back and forth until both locations read less than a tenth on the rod and the spider adjuster screws are snug enough to hold the barrel for machining ops. i double check directly on the lands where the throat will be with my long reach interapid test indicator to confirm it's far less than 5 tenths tir. once that is confirmed i can proceed with the work. after i pre-drill the chamber but before i bore it, i double check with the long reach indicator that the throat hasn't moved. once satisfied that the throat is still good, i bore the majority of the chamber to .010"-.020" under the reamer's shoulder major diameter. i bore it deep enough so the pilot still has a slight purchase on the bore to ensure it starts with a barrelled attitude.
the muzzle is set up similar except the spider adjustment screws are about 2" back from where the crown will be. i start by dialing in with the rod under the front spider using the front spider to adjust. i then move the rod to the muzzle and adjust with the rear spider. once both spots read better than a tenth off the rod, using a tenth indicator i directly read on the bore to confirm it is within a couple tenths at the muzzle and proceed with the crown.
when using the grizzly rod, i hang a plumb from the rear of the rod to keep the rod preloaded in the bushing and the bushing preloaded in the bore. i also set my indicator up so it is at the end of the barrel when the rod is as deep as it will be going and the magnetic base is on the tailstock, not the carriage or bed of the lathe. i slide the tailstock back and forth instead of using the quill. this meas that my leverage error on the rod is the same in both spots. if less than one tenth on the rod gets me far better than 5 tenths by direct reading at one spot, i'm pretty confident it will be as good 2" further forward with this setup.