The best chamber gauge for any rifle is the one that custom die makers use to make a die set to fit your gun. It is cheaper than anything you can buy and you can have it (them) in a few trips to the range. Any case that is fired three times in your gun with only being neck sized between firings is the best chamber gauge you can have. If the bolt closes without drag on that case it is perfect. if it doesn't then you need to find out where the case is hitting the chamber. The body may have expanded too much due to high pressures or the shoulder might be hitting slightly from too much pressure. If you are not exceeding the pressure in your gun it should fit the chamber perfectly with minimum clearance but no interference.
I have cases that I have used over the last 30 years that I have only neck sized and they chamber without any drag. I only neck size part of the neck leaving a portion of the neck expanded to center the front of the case in the chamber. My guns like this technique, even my 1942 issue 03A3 with a chamber and leade that is so worn that I can't get close to the lands with a 180 grain bullet in the case. It is just too far to the lands. The gun still shoots .6 to .7" groups at 100 yards. The chamber is well oversize in diameter to the point that if I full length resize I get body splits after 3 loads on a case. I have had the chamber checked with go-no go gauges and it is still in spec. It is just fatter than SAAMI specs.
I have cases that I have used over the last 30 years that I have only neck sized and they chamber without any drag. I only neck size part of the neck leaving a portion of the neck expanded to center the front of the case in the chamber. My guns like this technique, even my 1942 issue 03A3 with a chamber and leade that is so worn that I can't get close to the lands with a 180 grain bullet in the case. It is just too far to the lands. The gun still shoots .6 to .7" groups at 100 yards. The chamber is well oversize in diameter to the point that if I full length resize I get body splits after 3 loads on a case. I have had the chamber checked with go-no go gauges and it is still in spec. It is just fatter than SAAMI specs.
