then you can take that measurement and transfer it to the seater die, well not quite, but you can place a case in the shell holder with the seater die and seater plug backed out and with a bullet setting on top of the empty case raise the ram, lower the die close but not touching the mouth of the case, began screwing the seater stem down until it contacts the bullet THEN lower the ram a little and screw the seater stem down and began seating the bullet then lower the ram and measure the length of the case/bullet and compare the measurement with the marks on the cleaning rod measurement, once you have established the length of the bullet/case continue seating until the measurements match. Then the next time you want to load that rifle with that bullet use the transfer to adjust you seater die.
Or use a single edge razor with a piece of tap on one side or on the barrel to protect the muzzle, the razor will give you more accurate marks. OR you can cut a cleaning rod off to give you a rod that protrudes from the barrel, no particular amount just make it close when it is against the bolt face, insert the rod, measure the rod protrusion and write it down then stick a bullet you are going to use to develop a load in the chamber and with a weight or pencil drop both in the chamber, bullet first then insert the rod in the muzzle end until as Ridge Runner said, stop when contact is is felt with the nose o fthe bullet, then with the other two hands measure the protrusion of the rod, the difference between the two readings will give you the maximum length of the case for that rifle and that bullet with that case, still again you have a measurement with no place to go, no transfer, still with the measurement you can seat a bullet in a case and set the seater die up to seat bullets, start seating and measuring once you get close use the dial caliper to determine the height of the seater plus to cut down on time when seating bullets.
Or you can get a rod with an adjustable collar with a set screw, insert the rod against the bolt and slide the colar down to the muxle and secure, then place a bullet against the lands and measure the distance from the muzzle of the barrel to the adjustable collar, the reading will give the the maximum length of that bullet in that chamber for that case, still again, no transfer just a measurement.
F. Guffey