carry comp pistol compensator
Courtesy Griffin Armament
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carry comp pistol compensator
Courtesy Griffin Armament

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.

Courtesy Whitaker Behrens

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…

more power meme

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.

Courtesy Whitaker Behrens

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.

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  1. Interesting!

    Good layman’s description of the physics / dynamics of semi-auto reliability.

    Never had the desire to add a comp to any of my pistols…now I know why.

  2. Thanks, that was an interesting article.

    I do have an honest question, though. I was under the impression that “You’ll injure yourself when shooting from retention” was fact, not a myth. My understanding is that if you shoot, for example, from the hip, you could get a blast of redirected hot gas to the face. Is that not true? If not, why not?

    Thank you

    • I’ll reply.

      The reality is that most defensive calibers don’t produce enough gas to cause a problem.

      If you have a compensated gun, hold a sheet of paper a foot over the comp and fire a shot. The sheet will flutter, but no damage will be done.

      I tried this experiment on the cylinder gap of my 500 smith and wesson and it blew a charred hole in the paper. But then we are talking about a round with 6 times the energy of a 9mm and we are also gathering the gas right at the chamber, rather than at the end of the barrel.

      One other reason you don’t need worry is that the majority of comps direct most of the gas out of the top. The proper way to shoot from retention involves rolling the gun out so that the butt of the grip is against the body. This indexing will direct gasses whatever they are, away from you.

  3. I’d love to pimp out one of my Glocks with a comp and all the goodies to the max. Just one, because reasons. But alas, threaded barrels are illegal in CA due to the fact that someone just might install a suppressor (which is also illegal here, but hey).

    By that logic, any and all guns should be illegal because someone might commit a crime with one.

    • There’s no requirement that a compensated barrel be threaded, just order a longer aftermarket Glock barrel and experiment to your heart’s content…

      • True, there are longer barrels with comp ports cut directly into them…forgot about that.

        • I put a longer 2 port compensated barrel on my G21. No issues with even the cheapest ammo.

  4. I’m a physics geek and a gun guy. I was reading this just waiting to find a mistake that the author made.

    I didn’t.

    Other than the fact that he used “effect” a couple of times when he should have used “Affect”. Its all right.

    To expand on his admonishment to not install a lighter recoil spring, lets look at the glock.

    The recoil spring obviously pushes the slide closed. Not so obviously, it also resists the rearward pressure when you squeeze the trigger and the action presses the striker rearward. The recoil spring is what is keeping the slide from moving back rather than the striker.

    I’ve seen well worn Glocks have reliability issues if the striker spring is changed and the recoil spring assembly is not.

    The counter to a lighter recoil spring, if you wanted to try such a thing would be a lighter striker spring. This works great. 99.9% of the time. And as such is unacceptable for a carry gun. But great for a game gun.

    This is because you are now striking the primer with less force. This is fine when I’m shooting in a match and my reloads are loaded with Federal Primers (notoriously easy to ignite) and my gun is well lubed.

    But if you are trying to ignite old nato or com block ammo with very “hard” primers you will have problems.

    Bottom line, don’t change the recoil spring.

    Load hotter ammo.

    One thing not mentioned is another way to increase slide speed and make sure it reciprocates all teh way back.

    That is to lighten the slide. There is no real downside to lightening the slide to compensate for the addition of a compensator other than the cost.

    So that is another option.

    Another equation to keep in mind greatly simplified is.

    slide speed = ammunition power / (slide mass x spring weight)

    This equation tells us 3 things about the relationship between slide speed, slide mass, ammunition power, and spring strength. .

    1) increasing ammunition power increases slide speed.
    2) decreasing slide mass increases slide speed.
    3) decreasing slide mass increases slide speed.

    Remember in HS physics when you complained “When am I ever going to use this crap”. Now is when

    • He kinda mentions lightening the slide when he says milling the slide may change the energy requirements.

    • When I got my wife her G19, she had difficulty holding the gun and got a lot of stovepipes due to “weak wrist” grip. Granted, she’s a petite gal. So I got a softer recoil spring to help the slide cycle a little faster. Worked very well to eliminate stovepiping, but the trade-off was fouling of the safety plunger due to the quicker extraction of the spent case before the powder was fully burned. Went back to the OEM spring and just told the wife to learn how to hold the gun more firmly.

      Geez…just had a thought, which I’d never thunked before now…what if I try swapping out the OEM barrel with a longer one with comp ports in it? Hmmm….

    • So many words (in the article and reply), so much fail. Sorry you didn’t find errors. Maybe you aren’t as much of a “physics guy” as you thought. How about the claim that a 115 gr 9mm would be low energy, when it is the highest of the standard 9mm loadings? Heavier bullets go slower, and the increase in the linear factor of mass doesn’t overcome the geometry factor of lower velocity. How about the total absence of the term/consideration of “momentum?” What useful work are the gasses escaping from an uncompensated muzzle performing that is “robbed” by the compensator? Hint: none. Explaining what is really happening will take to long for me to tap out on a phone keyboard. In short, the solution of NATO/124 gr +P has about the same energy as 115gr standard, which invalidates the entire thesis of the article. What it does have is 15% more momentum.

      • While I didn’t specifically use the word momentum, I did state that the factors that go into the Energy Input are a combination of gas pressure AND bullet weight. The purpose of the article was not to give a physics lesson, but to relay knowledge – earned through trial and error of many hours and rounds fired – in a simplified manner that can most easily be understood by the uninitiated. Generally speaking a 115gr standard pressure 9mm round will have the highest gas pressure of the standard pressure loads – But through actual experience of testing every combination of bullet weight and standard/+P/+P+ pressure rounds through my compensated pistols, I found that the additional mass of a 124gr projectile combined with the slightly higher gas pressure in +P rounds resulted in much better reliability than lower weight 115gr standard pressure loads. This is corroborated by many anecdotal reports from other shooters who have run the same tests through their own compensated pistols. Nearly everyone who has actually taken the time to do the testing on various bullet weight and gas pressure combinations has arrived at the same conclusion: For short one- and two-port compensators, the best results and reliability are achieved by medium weight, higher pressure rounds

        • Your results with lighter vs heavier bullets makes perfect sense. There is a reason that you load less power with heavier bullets than with lighter bullets.

          The increased inertia of the heavier (more massive) bullet resists movement more which increases chamber pressures.

          I own a copy of a great internall ballistics software package called quickload. Its a great way to do what ifs.

        • I really wish there was an edit button. But one more thing.

          I have a threaded bbl for one of my G34s that I bought to use with a can. A friend gave me a couple of Lone Wolf compensators. I gave them a try and promptly began having problems because my hand loads wouldn’t cycle the action.

          I did play around a bit and ended up using a good quantity of relatively slow burning powder (AA5). This gave me a lot more gas to work with and I was able to make the gun shoot reliably and very flat.

          It was just a exercise in reloading and curiosity. Once I figured it out, I never made any more because I’m happy shooting without a comp.

      • I think for obvious reasons the author didn’t get into the difference between Kinetic Energy and momentum.

        As I’m sure you know KE increases as a square function of speed and Momentum increases as a linear function of speed.

        I didn’t get into it because I wanted to try to keep my response at about the same level as the authors. I though it was about right. Not too oversimplified, not too complex where people’s minds start to wander.

      • What useful work are the gasses escaping from an uncompensated muzzle performing that is “robbed” by the compensator? Hint: none.

        I came to say the same thing.

        I believe the “problem” that a handgun barrel compensator introduces is more mass at the muzzle which resists the barrel tilting up during the firing cycle.

        That being the situation, a cartridge with a “hotter” load or a heavier bullet produces more recoil to overcome the additional mass and therefore additional inertia required to tilt the muzzle of the barrel up and fully cycle the action.

        Isn’t this the very same “problem” that suppressors create on semi-auto handguns which do not have blow-back actions? Such semi-auto pistols require a Nielsen device in order for those pistols to cycle reliably. Just as hanging a suppressor on the muzzle of handgun increases the mass and interferes with the ability of the barrel to tilt up and therefore cycle properly, so does hanging a compensator on the muzzle of handgun.

        • The Silencerco Omega 9K, one of the more diminutive suppressor options for a 9mm Pistol, weighs 7.2oz according to the manufacturer’s spec sheet. The specific compensator on my handguns (which is a good average example of the short one- and two-port compensators this article references) is listed by the manufacturer as having a weight of 0.85oz. Weight of the compensator isn’t the factor that effects reliability, as the pressure of the gasses being forced out the top of the compensator during firing greatly exceed the weight of the compensator itself. You can induce reliability issues in locked-breech tilting-barrel pistols by creating so much compensation pressure that it resists the necessary upward movement of the end of the barrel when cycling, but it requires much higher gas pressure than what would be found in off-the-shelf FMJ and JHP loads. This is one of the known issues when trying to build a full-on Open division race gun using a Glock or other modern duty pistol as the base of your build, and running USPSA Major PF ammo through a much larger compensator

        • rududai13,

          Hah! I was reading the first sentence of your response when my brain raced ahead to the same explanation: the compensator’s very design — to redirect muzzle gasses upward and push the muzzle down — resists the necessary upward movement of the muzzle to cycle the pistol!

          My intuition tells me that plays a far more significant role than the added weight (and hence inertia) of the compensator itself.

        • Yes and no, like I said it can create problems but you really only start to see that in extremely overloaded rounds approaching or exceeding higher power factors used for competition Open guns. With these shorter compensators designed for factory loads (standard and +P pressures), there’s a butter zone where the gas pressure is high enough to counteract recoil but not so high that it impedes the ability of the barrel to tilt and complete the full cycling process. One thing I didn’t mention in the article is that during my testing I found that standard pressure 124gr loads were just as reliable as 124gr +P rounds, but the +P loads actually had less felt recoil than the standard pressure 124gr rounds through the same compensated setup. The higher pressure of the +P rounds creates more downward force when escaping through the top ports of the compensator, and thus counter-intuitively causes the muzzle to rise less in recoil as compared to a lower pressure round with the same grain weight bullets – without negatively effecting cycling reliability. In contrast, the greatest reduction in felt recoil I’ve experienced was provided by Inceptor RNP 65gr +P frangible rounds (muzzle velocity of 1,600+ FPS through a 4” barrel): If not for the tremendous noise and bright flash of burning powder that accompanied each shot, you would not be able to tell the gun had fired because there is nearly zero muzzle flip or felt recoil of any kind. Those rounds however don’t provide for dependable reliability, quite possibly because there is so much gas pressure that the compensation effect begins to interfere with the ability for the barrel to tilt upward and properly cycle. This observation has also been corroborated by other shooters who have performed the same tests through similar setups

  5. I was running a Lone Wolf bullnose comp on my Glock 19 but I had to remove it due to too many FTE’s. Didn’t matter what ammo I was using – el cheapo, FMJ, +P HP, etc.

    I am on my church’s safety team and I need to carry a gat that it 100% reliable.

  6. More power, sure . . . . or you could SLIGHTLY reduce spring power . . . . or you could cut speed holes into your slide like the youths are wont to do these days.

    • lightening the slide will increase slide speed. But it needs to be enough to actually matter, not just look sexy.

      Look at the hole in the top of a G34/35 slide. We’re talking about something like that.

    • Oh yeah, there’s still a Presidential race happening. Let’s see if the Bernie Bros step into line behind Biden like they’re supposed to.

    • Either that or get Berned again at the DNC Convention.

      Wonder how his sycophant comrades followers will take the news?

      Did Biden offer him cash like Hillary did? For an avowed Communist he is about a Capitalistic SOB….runs every four years and buys a new mansion.

    • Not surprised at all, who want’s a grumpy Communist yelling at them all the time, the Burnmeister is toast.

  7. Having ported/compensated wheelguns make sense, allows to use of heavier loads while controlling felt recoil, and in many cases reducing recoil allowing for more accuracy…

    All my wheelguns are factory ported…

    • If you despise recoil and muzzle rise (as I do), a compensator is worth looking into. Yes, 9mm is a relatively light recoiling round – so is 5.56, and many people still put compensators on their AR15 to reduce even the small amount of recoil it produces. If you could have a gun with the ballistic performance of 5.56 and the felt recoil of 22LR, you’d jump at a chance to shoot it. In my opinion, anything that reduces felt recoil and muzzle flip as close to zero as possible is worth a try. All of the handguns I own are compensated 9mms, I EDC one every single day, and I shoot them faster and more accurately than any other handgun I’ve ever shot. For me, the juice is worth the squeeze

  8. “How to Ensure Reliable Performance in Compensated Semi-Auto Pistols”

    Step 1: tell everyone that you are gay already

    Step 2: remove the compensator from your pistol as step 1 removed the need for you to demonstrate it to the world

  9. I feel compelled to note that the phrases “fixed constant” and “most ideal” have no place in civilized discourse.

    That is all.


    The Pedantic Pistolero

  10. The last two pictures in the article don’t seem to be loading properly – Is that just me or is anyone else not seeing them? Any way that can be fixed?

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