The Remington 209 Premier STS Shotshell Primers are made with a very closely controlled, specifically formulated chemical mixture to ensure that no matter the powder, ignition is always fast and consistent. Testing has shown a 40% decrease in velocity spread. The primers are made with a to the same tolerances as previous 209 primers and use the same load data. The 209 Premier STS Shotshell Primers are designed and tested to function in extreme temperature ranges from -20F to +150F. Each 209 Premier STS Shotshell Primer is produced to exacting tolerances with a deviation no larger than .0003 ounces. All 209 Premier STS Shotshell Primers are visually inspected and undergo critical ballistic tests.