Kaw Valley Precision PCC 6 Position Mil-Spec Kit w/ 10oz Buffer and XP SS Spring, Multi, Medium, KVP-PCC-MILSPECKIT-10oz

40 S&W .45 ACP and 10mm are a blast to shoot but can be tough on AR-15's internal components. Without a properly tuned blowback system you run the risk of being overly destructive on internal lower parts. Running a blowback AR15 with a suppressor can further increase the risk for damage.