A little over a year ago, we wrote about the Discreet Ballistics PopStop which is a barrel mounted valve and a CO2 cartridge system designed to inject a non-flammable gas into the suppressor replacing the oxygen inside the can thus eliminating the phenomenon of the first round pop. Back then, the PopStop was patent pending. Lately, Discreet Ballistics has announced that the patent (US 10,145,636 B2) has been issued.
The first round pop occurs at the first shot when the not completely burnt powder enters the can full of oxygen which supports the combustion resulting in a higher report and signature of gasses exiting the suppressor. It is not present at second and consecutive shots because the oxygen has been removed from the can. The first round pop normally happens in rimfire and pistol cans.
It is interesting to note that if the currently available PopStop requires to inject the CO2 gas from an external source (CO2 inflator), the patent shows another solution for carbines with the CO2 cartridge integrated into the gun and controlled via an electrically activated valve and a remote switch (see the drawing below). According to the patent, such a system will be convenient for carbines not requiring to reach forward to inject the CO2 gas into the can.
Another interesting aspect is that the patent also shows a suppressor design with a valve welded or screwed directly into the first blast chamber area. The screwed option is preferable because it will allow replacing the worn out valve. Currently, PopStop is available only as a direct thread adapter that adds a valve between the muzzle and suppressor.
I think this patent includes some great ideas which if executed properly can make a very cool suppression system. I hope in the foreseeable future, we will see a Discreet Ballistics carbine (or retrofit kit) with the integrated first round pop mitigation system.
Images from www.discreetballistics.com, US Patent # 10,145,636 B2