The theory it works. There are better methods of doing it, but note just because you are on the lands, it doesn’t necessarily mean you will be more accurate. Now, you should be aware of mag length as it can determine your overall length, this is more true of short actions though. You can buy a Hornady bullet comparator gauge that will attache to your caliper so when you have pulled the marked bullet out you can make an accurate measurement of your OAL TO OGIVE. This is more accurate of a measurement then to the tip. You can also compare what factory ammo measures (to ogive) and use that as a baseline, and move up from there. Obviously you must do the steps you noted for every bullet you want to work on, the best way is to find the actual dimension to YOUR RIFLE”S LANDS, and make sure you use the same exact gauge for all your measuring. You can do this easier if you have a RCBS Micrometer gauge which is a great investment IMHO. Good luck!