Editing Muzzle brake (section)

== Venting direction ==
[[File:Custom XD-40 V-10.jpg|thumb|[[Springfield Armory, Inc.]], custom {{nowrap|[[Springfield Armory XD|XD]]-40 V-10}} with ported barrel and slide]]
[[File:Heizer-DoubleTap.jpg|thumb|[[DoubleTap derringer|DoubleTap .45ACP derringer]] with ported barrels]]
Most linear compensators redirect the gases forward.<ref>{{cite web|url=http://www.brownells.com/aspx/ns/store/ProductDetail.aspx?p=5594&title=AR-15+LEVANG+LINEAR+COMPENSATOR|title=Brownells - Firearms, Reloading Supplies, Gunsmithing Tools, Gun Parts and Accessories|website=www.brownells.com|access-date=30 September 2007|archive-url=https://web.archive.org/web/20070930185156/http://www.brownells.com/aspx/ns/store/ProductDetail.aspx?p=5594&title=AR-15+LEVANG+LINEAR+COMPENSATOR|archive-date=30 September 2007|url-status=dead|df=dmy-all}}</ref><ref>{{cite web |url=http://www.joeboboutfitters.com/KIES_Blast_Master_Linear_Compensator_p/kies-blst%20mstr22.htm |title=KIES Blast Master Linear Compensator |access-date=2013-12-19 |url-status=dead |archive-url=https://archive.today/20131219041345/http://www.joeboboutfitters.com/KIES_Blast_Master_Linear_Compensator_p/kies-blst%20mstr22.htm |archive-date=19 December 2013 |df=dmy-all }} KIES linear compensator</ref><ref>https://www.youtube.com/watch?v=PY4-fmql19w HERA ARMS linear compensator</ref> Since that is where the [[bullet]] is going, they typically work by allowing the gases to expand into the compensator, which surrounds the muzzle but only has holes facing forward; like any device which allows the gases to expand before leaving the firearm, they are effectively a type of [[muzzle shroud]]. They reduce muzzle rise similarly to the mechanism by which a sideways brake does: since all the gas is escaping in the same direction, any muzzle rise would need to alter the velocity of the gas, which costs kinetic energy. When the brake redirects the gases directly backward, instead, the effect is similar to the [[reverse thrust]] system on an aircraft jet engine: any blast energy coming back at the shooter is pushing "against" the recoil, effectively reducing the actual amount of recoil on the shooter. Of course, this also means the gases are directed toward the shooter.

When the gases are primarily directed upward, the braking is referred to as ''porting''.{{citation needed|reason=even when using a muzzle brake (see below) it's called porting? Does not make sense.|date=August 2018}} Porting typically involves precision-drilled ports or holes in the forward top part of the [[gun barrel|barrel]] and [[pistol slide|slide]] on [[pistol]]s. These holes divert a portion of the gases expelled prior to the departure of the projectile in a direction that reduces the tendency of the firearm to rise.<ref>{{cite magazine|magazine=Popular Mechanics|author=Hearst Magazines|title=Jump Is Taken Out Of Guns By Cylinders On MuzzlePopular Mechanics|url=https://books.google.com/books?id=7-EDAAAAMBAJ&pg=PA248|date=August 1932|publisher=Hearst Magazines|page=248}}</ref> The concept is an application of [[Newton's laws of motion|Newton's third law]]; the exhaust directed upward causes a reciprocal force downward. This is why firearms are never ported on the bottom of the barrel, as that would exacerbate muzzle rise, rather than mitigate it. Porting has the undesired consequences of shortening the effective barrel length and reducing muzzle velocity, while a muzzle brake is an extension added to the barrel and does not reduce muzzle velocity. Porting has the advantage for faster follow-up shots, especially for [[Burst mode (firearm)|3-round burst]] operation.{{citation needed|reason=it isn't obvious why this would be the case, if it's true|date=August 2018}}