Lets get a few things answered as I have seen quite a few misunderstandings about compensators floating around.
Q: What is the difference between a ported pistol and a compensator?
A: A ported pistol works by machining holes or ports in the barrel of the pistol. These ports vent the gasses early that are pushing the bullet down the bore of the barrel. This does a few things. First, the main reason ports are used is to reduce the energy used to cycle the slide. Think of it as using a 3” barrel on a 5” full mass slide or lowering the powder charge of your ammunition. As soon as the bullet passes the ports, some of the gasses behind it are vented to atmosphere reducing the energy driving the slide rearward and the velocity of the slide. in extreme cases this can be observed in the ejection pattern of the pistol looking lazier than a non ported pistol counterpart. A slower moving slide with less energy will not transfer the same amount of force on the shooters wrist, therefore reducing muzzle flip and felt recoil (as long as proper shooting techniques are employed).
Compensators on the other hand work off somewhat of a different set of principles. Compensators work by applying gas pressure to the baffle and floor surface areas of the comp to generate forces that counteract recoil (Pascals Law states that Force = Pressure X Area) as well as slow down the slides rearwards velocity. The way a compensator primarily works is by allowing the same gasses pushing the bullet down the bore of the barrel to push on the forward wall (or baffle) and floor of the compensator to generate force on the barrel & slide that is opposite to the direction of recoil. The compensator is being pushed forwards and down whereas recoil occurs upwards and rearwards (aka "muzzle flip). Because the compensator is being pushed forwards, this also robs some of the energy that the slide uses to cycle and therefore will slow down the velocity of the slides rearward movement. Think of this as someone pulling forwards on your barrel as you try to pull your slide to the rear. An effective compensator makes it harder for the slide to unlock the barrel and cycle. This also reduces recoil in a similar manner to porting as it reduces the rearwards velocity of the slide and therefore the momentum the slide has when it reaches the rearmost point in it travel. This leads us to the next topic:
Q: Do I need to change my recoil spring when running a compensator?
A: Most likely yes. That is if your compensator is actually doing anything significant. On a Browning type action pistol like Glock’s, M&P’s, and many other modern pistols, the slide movement to the rear (against the recoil spring) unlocks the barrel to cycle and pick up the next round from the magazine. A well designed compensator will generate enough forward force to make it difficult for the slide to unlock the barrel as it moves to the rear. This is the reason why you would most likely need to lower the weight of the recoil spring on your pistol when you run a compensator. The recoil spring must be matched with the weight of the slide and the forces it encounters during cycling to achieve reliability. Here is the point. If the compensator on your pistol runs with any ammunition without any changes to the factory recoil spring, then it probably isn’t doing much for you to minimize muzzle flip and felt recoil. You basically just have a fancy barrel decoration. With an effective compensator you will most likely need to test a few reduced spring rates to find one that cycles and feeds reliably while also not beating the gun to death. Of course when changing anything about how the gun works and behaves you should thoroughly vet its performance before ever considering it to defend your life or the lives of others with it. A compensated gun with a properly tuned recoil system can absolutely be reliable enough to carry and use for self-defense.
As always if you have any questions don't hesitate to ask at namelessarms@gmail.com or on social media @namelessarms.
Happy Shooting!
-Nate K.