least amount of taper is
Not all 9mm Luger ammunition has the same amount of taper. Taper is defined as case head diameter minus case neck diameter. SAAMI 9mm Luger specifications show a taper of 0.010-inches (head to case neck; 0.014-inches for rim to case mouth). Samples of 15 different factory loads in the authorâs possession had an average taper of 0.0094-inches. The least amount of average taper was 0.0065-inches and the most was 0.0135-inches.