Tight Case Length Gauges

Cases that have been resized have had the neck reduced in diameter by forcing it into the die, and then by pulling the case out of the die, the expander has opened the case mouth to a size usually .001" smaller than your bullet diameter.
With Pistol cartridges, case neck wall thickness makes the difference.  Sizing the case from the outside squeezes the case down.  If the case wall is .002" thicker than nominal, that makes the inside diameter of the mouth .004" smaller, making the gauge tight.
The gauge should be that same .001" smaller than the neck diameter.  If it fits tight in your cases, you can simply reduce your gauge diameter:

Remove the gauge from the cutter. Clamp the gauge in a drill chuck and spin it.  Take some 320 grit emery cloth and sand down the large end until it fits into your case.  This is only a thousandth of an inch or two, so it does not take much to remove it.
If you are having trouble getting the gauge into the cutter, take a hand drill and lock the Gauge into the chuck - be sure to wrap the Gauge in a shop rag to prevent the drill from damaging the Gauge. Now screw the Cutter on. You can use a pliers on the Cutter if you can't do it by hand. They are made tight so they won't work loose.

If you do not feel comfortable performing this on your own, you may send the gauge and a sample case to us and we will modify it for you.