How to Ensure Reliable Performance in Compensated Semi-Auto Pistols

By Whitaker Behrens

Compensated handguns are more popular than ever. The unique timing of the original Roland Special build combined with the ability of social media to quickly and efficiently spread information ignited a compensated pistol firestorm that had, until this point, been relatively dormant outside of the competition realm.

As is often the case with a rapid expansion in popularity and adoption of a new system, though, wider acceptance has also brought with it several misconceptions and misunderstandings.

While many in the community of gun owners have done an excellent job of dispelling some of the more ridiculous myths and claims about pistol comps (see classics like: “It’ll blind you at night,” “You’ll injure yourself when shooting from retention,” etc.), there is one widespread misunderstanding that I’ve seen continually pop up among even some the more experienced shooters in the community. That has to do with the reliability of compensated pistol systems.

I will assume for the sake of brevity that most of you already know what a compensator is and what it does (for the few who are still unaware, you can read this great article from Guns & Tactics.

For the purposes of this discussion, the most important information to understand is how a compensator compensates and what effect that has on the overall system of a semi-auto pistol. Very basically, a compensator harnesses energy from the expanding gasses of a fired round and redirects some of that energy upward. That in turn counteracts the natural tendency for the muzzle to rise during recoil.

This same energy from a fired round, however, is what’s responsible and necessary for fully cycling the slide of a semi-automatic pistol. The high rate of reliability found in most modern duty pistols (GLOCK, P320, M&P, etc.) is in part due to the careful tuning that goes into making sure the widest possible range of commonly available ammunition provides sufficient energy to fully cycle the action.

In reality this is a complex interaction between multiple springs inside the gun, the weight of the slide, the ammunition you’re shooting, how clean and lubricated the pistol is, and any myriad other factors that don’t need to be understood for our purposes. A highly over-simplified way to express this interaction is through the following equation:

Cycle = Energy Input – Energy Required to Function

In our simple equation, cycle is defined as one complete, successful cycling of the firearm from the time the bullet leaves the barrel to when the slide fully returns to battery on a new live round, ready to fire again.

Energy Input is wholly dependent upon the individual round of ammunition being fired and is a combination of resultant gas pressure and bullet weight.

Energy Required to Function is exactly as it sounds; the amount of energy required to overcome all of the springs, friction, resistance, inertia, etc. that are present within the pistol itself.

Generally speaking, as long as the Energy Input is greater than the Energy Required to Function, the gun will Cycle successfully. Reliability can be thought of as a function of successful individual Cycles over the number of attempted Cycles.

When we look at the Cycling of a pistol in this simplified manner, it becomes readily apparent how ammunition choice and modifications to the gun itself can affect reliability. If you use low-power range ammunition (115 grain standard-pressure 9mm, for example) in your gun, there is less Energy Input in the system and therefore there must be less Energy Required to Function in order to Cycle.

If you make modifications to your pistol such as changing spring weights, milling the slide, or mounting a red dot, the Energy Required to Function can increase or decrease, meaning ammunition of more or less Energy Input may be required to reliably Cycle the pistol.

A compensator, though, is somewhat unique among modifications, as it generally completes its primary function and effect on the Cycling process in the split second of time between when the bullet is leaving the barrel and when the barrel unlocks from the slide…before the normal series of mechanical operations involved in the pistol Cycling begins.

When adding a compensator to your pistol then, you should not think of it as increasing the Energy Required to Function, but rather immediately decreasing the initial Energy Input.

Since a compensator uses some of the Energy Input that would normally be available to help the slide Cycle, there is less energy remaining to overcome the Energy Required to Function. In our simple equation, the change appears as;

Cycle = (Energy Input – Energy Utilized by the Compensator) – Energy Required to Function

In order for the compensated pistol to Cycle, the Energy Input must be sufficient to cover the Energy Utilized by the Compensator and have enough energy remaining to overcome the Energy Required to Function (emphasis added because this is the key take-away from this very lengthy piece).

This is why some pistols that ran reliably on low-power range ammo can start to develop reliability issues when running the same ammo after adding a compensator. Once the compensator has done its job, the remaining Energy Input isn’t sufficient to overcome the Energy Required to Function.

Different compensator designs can be more or less effective at redirecting the expanding gas from a fired round, and will therefore rob more or less of the Energy Input.

So, now that we understand how a compensator can affect the reliability of a pistol and why, the question is what can we do to maintain the best reliability while still enjoying the positive effects a compensator provides? The answer can be found in adjusting one or more variables from our compensated handgun Cycling equation:

Cycle = (Energy Input – Energy Utilized by the Compensator) – Energy Required to Function

Since we know that the Energy Utilized by the Compensator is a fixed constant based on the design of the compensator, our choices come down to adjusting the values for either the Energy Input or the Energy Required to Function.

Adjusting the Energy Required to Function would most often be accomplished by changing recoil spring weights to something lighter than the stock pistol originally came equipped with. However this can very easily upset the delicate balance of the multiple springs present in your pistol that were tuned by the manufacturer to work in conjunction with each other and provide the best reliability possible. That could induce even more complex reliability issues than it was meant to solve (just ask an Open division competition shooter about tuning spring weights and watch the resulting PTSD panic attack).

Swapping spring weights is not advisable on a gun meant for duty or carry unless the shooter has significant experience and knowledge on how to maintain proper balance of all the springs present in their pistol.

So what’s the best way to ensure reliable Cycling of a compensated pistol without adjusting the Energy Required to Function? Get ready to channel your inner Jeremy Clarkson…

Increase the energy input! Run hotter ammo than your standard low-power range ammo. This will both help your compensator run more effectively and ensure there’s plenty of power left to overcome the Energy Required to Function and maintain consistent Cycling reliability.

Most single- and dual-port compensators meant for duty/carry guns tend to run very reliably on high-pressure, medium grain-weight loads. A good place to start for 9mm is to look at 124gr NATO FMJ loads for range/practice ammo, as these rounds are loaded to about the equivalent of +P gas pressure while still being relatively inexpensive to buy in bulk.

For self defense ammo, take your pick of the many 124gr +P modern JHP loads available on the market today.

If you’ve just installed a new compensator on your favorite blaster (or done any modifications to the major function assemblies, for that matter), it would be most ideal to purchase the widest array of commonly available ammo loads possible and run as many through your pistol as you can.

This will generally give you a fairly good indicator of what your absolute minimum Energy Input needs to be based on your specific pistol setup, and you can then enjoy thousands of rounds of (hopefully) malfunction-free shooting with your modified pistol.