Not sure what you mean by changing a chuck. My D4 camlock has 3 socked screws my chuck wrench fits that unscrew about 3/4 turn, then tap the chuck with a soft hammer. Be sure to put a piece of wood under the chuck to protect the ways. The sockets are located just behind (left side) the chuck on the spindle. Just line up the scribed lines.
I make a short ID tapered socket out of aluminum that fits the taper of the barrel. Put the barrel on centers with the socket snugged on the barrel, turn the OD a few thou then chuck it in the 3 or 4 jaw and indicate it. It seems to work for me to around 0.0005" in the 3 jaw and right on in the 4 jaw.
I haven't had any trouble holding all the barrels I've done, except for Rem XP-100 barrels that need the socket because of the triple tapers, in the chuck with copper or brass pads on the jaws. I usually turn the shank and a 1/2" or so at the muzzle end of the barrel on centers then chuck it up in the 4 jaw and indicate. Most of the time I don't even use a dog because center friction and light cuts. Or use a steady rest and hold the muzzle in the 4 jaw. (The reason for the 1/2" muzzle end turning.) Hope this helps some.
