AR-15 H2.5 Carbine Buffer (5.1 Ounces)AR 15 H2. 5 Carbine Buffer (5. 1 Ounces) Here is the perfect balance between and H2 AR 15 Buffer and an H3 AR 15 Buffer. When using super safeties and FRTs, it is very common to need a heavier buffer in your firearm. Well, we believe with the 2. 5 you have the perfect balance because the H2 is 4. 8 ounces and the H3 is 5. 4 ounces therefore splitting the difference right in the middle of 5. 1 with a solid construction has shown to be a very effective