The Lee APP Bulge Buster Kit, when used with the appropriate Lee Carbide Factory Crimp Die, effectively restores the free function of rimless cases that have low base bulges. These bulges often occur when cartridges are chambered in guns that don't fully support the case or when cases are resized in carbide dies from manufacturers other than Lee. The bulge typically results in a noticeable stop ring near the base of the case. This issue is commonly found in mixed range brass. The Bulge Buster Kit provides a simple, cost-effective solution to restore these cases to full functionality, ensuring reliable performance and preventing feeding issues in your reloading process.