On the first shot, unburnt propellant mixes with the oxygen sitting inside the suppressor and burns a second time in the can. That secondary combustion often makes the round louder than the ones behind it. Once that oxygen is burnt off, follow-up shots settle into a quieter, steadier number. This is commonly called first round pop, or FRP. Because a hunter, marksman or defensive shooter may only ever fire one or two rounds, we isolate the first-round data rather than bury it in the average, and present it here. The magnitude of first round pop varies substantially across designs.
Shooter's ear · LIAeq100ms (dB)
| Host | First round | Subsequent | Pop |
|---|
| 4.1" Handgun9mm Federal 115gr Champion | Not yet tested | Not yet tested | Not yet tested |
| 4.1" Handgun9mm Federal Syntech 147gr | Not yet tested | Not yet tested | Not yet tested |
| 20" Bolt Action7.62x51 Lake City M80 | Not yet tested | Not yet tested | Not yet tested |