When dealing with a wildcat caliber you have to reform a standard case to fit your own. Doughnuts or a ring of thicker material occurs down in the neck when reforming a case so that some of the material from the original case forms the new neck. Thats because the body of a case have thicker material than the neck.
The doughnut is not limited to wildcat cases. Depending on brass flow and resizing methods it can occur in any cartridge.
The easiest way to handle it is to ensure the driving band (rearmost portion of bullet that is at bore diameter) is at or above the doughnut region. This region is the neck / body junction. If your chamber (and magazine in a field arm) will accommodate this you can ignore the doughnut.
If your bullet encroaches in this area, you need to inside ream the neck all the way past the neck / body junction.
Proper resizing goes a long way to minimize this. Changing brass may help as well. It’s easier to avoid it than it is to correct it.
This tip is for anyone who does or does not use a rangefinder while bowhunting, here is a simple and easy way to judge the distance to your game. Whether you’re in a tree or on the ground you can use this method at any time. Marking the distance before a hunt from your stand is a helpful way to determine the distance. I use either colored pins and/or hunters tape to mark trees at 20, 30 and 40 yards in 3 different spots around my stand. With those 9 markers I have a good chance that...