Home Forums Hunting & Shooting Gunsmithing Question about rifle barrel - chamber/throat

A little further explanation on how to accomplish it with minimum tools. Place the barrel vertically in the vise and drop an empty case in the chamber and take a measurement from the base of the case to the torque shoulder of the barrel. Then, insert the "dummy" round and re-measure. Advance your throat reamer the difference between the two measurements.

When customers leave it to me to determine and set the throat length to a particular bullet, without providing a dummy, I simply drop an empty case into the chamber, as in the above example, and take the measurement. Then I drop the actual bullet into the chamber where it comes to rest against the lands, and with my depth mic, measure the distance from the mouth of the chamber to the base of the bullet, and then transpose that to where the bullet would sit in the empty case to determine the exact distance needed to go to set the depth.

It's a lot less of a hassle using a seated dummy round if you can. And if the customer doesn't have any preference for seating depth, I always set the throat so that the base of the bullet is flush with the base of the neck. And if that bullet is a boat tail, unless otherwise specified, that area is the transition point where the parallel portion of the bullet ends, and the boat tail begins. Of course, whatever you do, it has to fit the magazine.