With the overall-length gauge inserted firmly into the rifle’s chamber, push the bullet into the rifling with the adjustment rod and lock it in place with the thumbscrew.

Then I discovered the best way to determine and verify proper bullet seating. This method uses the bullet ogive instead of the tip. Practically speaking, the forming die that swages the final bullet profile yields a much more consistent datum at the ogive than the nose. The bullet tip doesn't engage the rifling, so why set the COL using it as the point of reference?

Hornady's Lock-N-Load Overall Length Gauge used in conjunction with the company's caliber-specific comparator/bushing attached to a caliper will ensure that the bullet is seated precisely where you want it. The gauge is comprised of a hollow tube threaded on one end to accommodate mounting a specially modified cartridge case. A slender plastic rod contained within the tube adjusts the bullet's position in the case mouth.

Using the overall-length gauge is quite simple compared to the crude scheme I described earlier. First, you remove the bolt to gain clear access to the chamber. If you have a semiauto or lever-action, open the action and use Hornady's curved L-N-L Overall Length Gauge. Screw the special modified case onto the tube tightly so the subsequent measurement is exact. Then adjust the rod position so you can place the bullet into the case mouth far enough so that it cannot engage the rifling.

Before proceeding, make sure the gun is unloaded and the chamber is clean and dry. Oil or powder residue remaining in the chamber will prevent the case from seating properly and cause an incorrect reading. Using the tube, insert the modified case into the action and firmly seat it in the chamber. While securely holding the tube/case assembly in place, push the adjustment rod until the bullet ogive engages the rifling. Lock the rod with the thumbscrew mounted on the sleeve at the end of the tube.

To remove the gauge, you can either carefully pull it out, or you can use a wooden dowel or cleaning rod to gently tap it free if the bullet binds in the rifling. If the bullet is disengaged from the case during this step, simply reinsert it into the case mouth and measure the overall length. The locked adjustment rod will ensure that it seated to the correct depth. Of course, one reading is not likely to be absolutely correct, so take several using multiple bullets to obtain an optimum max overall length.

As Hornady's instructions clearly describe, your technique using the gauge can easily affect the results obtained. Again, consistent, repetitive actions lead to more uniform and accurate measurements. If you're loading a plastic-tipped or FMJ bullet--i.e., one that's not easily damaged--you can simply measure the overall length without further ado. However, if you're loading a softpoint bullet or you want to be as absolutely precise as possible, continue to the next process.

Hornady's bullet comparator kit includes a universal body and several caliber-specific inserts. Select the caliber you're loading, attach the insert to the body, and then attach the assembly to the moveable blade of the caliper. Close the caliper until the comparator body/insert assembly is sandwiched between the blades. The reading should be close to 1.000 inch, and if you're using a dial caliper, you can adjust the dial to that setting.