Backpressure

When a bullet leaves the crown of a barrel, it is followed by a barrage of hot, high pressure gas that are being quickly dumped into the atmosphere that we the end user experience a noise and concussion. This event will be called pressure at the muzzle. When we attach a suppressor to the end of our firearm, we are doing one of two things with that pressure wave. Firstly we are trying to make that pressure wave travel a longer path before leaving the front of our firearm to give it time and space to dissipate. Secondly, we are trying to trap it and hold it in a contained space, letting it slowly leave the front of the gun resulting in a more diffused lower amplitude pressure wave. Or in plain english, we are flattening out that blast wave. This is all good stuff, however the issue arises, when you you diffuse the hot gasses out over time, we can have a scenario where the firearm's action opens up and gives the hot gas a path to escape that wasn't there before. These paths could be the breach of the firearm very close to your face, or these could be the contact points where a semi automatic firearm recycles gas to operate the system. Either way, the end result is more gas coming back at the user, and more gas, force, and wear being imparted on your firearms.

Remember that a suppressor is spreading the pressure out over time. Now understand that the unsurprised time horizon was one tiny fraction of a second. A suppressed firearm took that tiny fraction of a second and made it a slightly larger but still tiny fraction of a second. So If we have a manually operated firearm, such as a bolt action hunting rifle, where the chamber never opens, a high backpressure suppressor is good! It means we are using the ability to trap gas to it's fullest. Hosts that are backpressure agnostic are bolt actions, lever actions, single shots and any other firearm that has a breach that stays closed until the shooter cycles it manually.

This is where things get tricky. Some hosts, like the classic mk18 the military uses, can handle a ton of backpressure at the cost of increased wear and gas to the face. However, in most scenarios it will still cycle where other platforms would jam. This is where we encourage every user to do some research on how their host behaves when suppressed. Do not hesitate to contact your manufacturer for advice not how to both successfully suppressor your firearms and not void a warranty. For a little more insight into what hosts make good hosts, look into how your bolt interfaces with the cartridge. Many modern platforms have a delayed/mechanical bolt interface where the bolt has to rotate or move before disengaging. This will keep the action closed longer, providing more time for the gasses to go out the muzzle. Look also for systems that have gas tuning mechanics, such as a adjustable gas blocks with suppressor settings. While these don't guarantee perfect function with high backpressure systems, they could be one of many mechanisms that a good suppressor host would feature.

With all that said, if your host is semi-auto and seems like it will problematic with a high backpressure host, no problem, start looking into low backpressure solutions. Some designs do a great job making the gas travel through long pathways without getting trapped in high pressure pockets that would impart backpressure. These design have almost zero perceivable difference on the user and host firearm and can be a great choice for those who want suppression without the risk of needing to tune the host firearm. Historically these designs could have the compromise of still sending a large pressure wave into the environment front of the muzzle. User's might report a "boomy" firearm when shot near walls or indoors.[p]That said, low backpressure doesn't mean always mean compromise, most of the top performing suppressors use a hybrid design that both traps gas in high back pressure chambers and has low backpressure venting systems to keep gas traveling forward. You can have your lunch and eat it too with modern suppressor design. Just consider, these modern hybrid designs sometimes have added internal complexity that can increase weight and have different wear patters. For this reason, if you know you are using a manual firearm and are weight conscious, the perfect suppressor will likely be a traditional high backpressure can.