General

Revolvers: Understanding Cylinder Gap — The Uses and Dangers

Fire from the cylinder gap of a revolver

I am confident that most shooters, especially those new to shooting and anyone new to the revolver, are unaware of what the ‘Cylinder Gap’ is. I know that in my own case, I had been shooting revolvers for several years before I learned the importance of the cylinder gap. To introduce those new to the revolver, and to help save them a painful lesson, I thought I would provide some cylinder gap information.

Today, due in no small part to the entertainment industry, and the fact that the firearms industry has fallen short, revolvers and a real understanding of them have played second fiddle to semi-automatic firearms. Revolvers may be old, but they work with a simple elegance. Newer technology always gets the benefit of R&D and advertising budgets because that is what people buy the most.

cylinder gap of a much used Smith & Wesson Model 57 in .41 Remington Magnum
The ‘cylinder gap’ of a much-used Smith & Wesson Model 57 in .41 Remington Magnum circled in red.

Lord knows how I like the new stuff too, but I’ll bet I have as many revolvers as I do pistols. Why do you suppose that is? Well, for one reason, they are more versatile and can safely accommodate much more powerful cartridges… No question!

Revolving Design

To state the obvious, revolvers are called revolvers because of their signature design. It’s the round cylinder located at the breach end of the barrel that contains the firing chambers where the cartridges reside. I suppose you might also call it a revolving non-removable magazine.

Because of this defining design feature which requires rotation and a fixed, yet separate, barrel there is a slight space separating the cylinder and barrel. Now, because of the necessities of mass production manufacturing, the bit of space between the cylinder and the barrel is as small as possible, but still allows the cylinder to freely rotate.

If you look closely at a revolver, you will no doubt observe that at the location where one of the cylinder’s chambers aligns with the barrel. There you’ll notice a very teeny tiny sliver of light between the front of the chamber and the rear of the barrel. Most gun people describe it as being, “about the thickness of a business card.” This space is technically called the cylinder gap and exists in all revolvers.

demonstrating the proper grip when shooting a revolver
The proper grip for a revolver.

Cylinder Gap

Revolvers would not be revolvers without a cylinder gap. Due to the escape of some gases through the cylinder gap, the velocity of the bullet coming out of the revolver is slightly reduced. There have been designs that attempted to deal with the gap issue, so all of the expanding gases would act upon the bullet. It must be noted at this point that, historically, in some revolver designs (e.g. the Belgian Nagant 1895 model), this gap is sealed when the weapon is cocked but in most revolver designs, this gap is left open at all times.

When a revolver is fired, several things happen in rapid succession. First, high-pressure gases are generated in the chamber and expand. These expanding gases cause the brass cartridge case to push slightly against the sides of the chamber. At the same time, the rim of the cartridge seals the back of the cylinder.

hot dog held next to the cylinder gap of a revolver as it is being fired
Here we see what would happen to a finger or any delicate body part placed in front of the cylinder. Of course, we are using an innocent hot dog here as a stand-in for one of your body parts.

This prevents hot gases and debris from leaking out of the rear of the cylinder. As that is happening, simultaneously those same high-pressure gases are pushing the bullet out of the brass case and forward in the chamber. As the bullet reaches the end of the chamber — to start its journey into the barrel — it must negotiate the cylinder gap.

It is at this part of our narrative that things really get interesting. The alignment of the cylinder and chamber must be perfect with the barrel. This alignment, and the ability of a given revolver to repeat that perfection with every chamber (time after time) is referred to as the revolver’s timing.

As experience has taught us, all things mechanical can miss the mark of perfection. To help compensate for this, the breach end of the barrel has (for lack of a better description) a funnel built into it that is referred to in firearms lingo as… Get ready… the Forcing Cone. Clever those gun guys are. Aren’t they?

cylinder gap of a revolver as it is being fired showing the hot dog exploding
If this graphic depiction does not convince you of using proper grip technique, nothing will. Just cut off those body parts now and save us the trauma. Seriously, revolvers are very safe to use, if you just follow proper safety procedures and keep everything you value behind the ‘cylinder gap.’

As the bullet — through engineering, manufacturing, or magic — makes the transition to the barrel, it is forced to align with, and take, the rifling. This happens while most of those still expanding gases follow it into the barrel continuing to propel it, pushing the bullet out to the ‘only gods know where.’ It is at this point in the narrative that we must note… A small amount of hot gas can, and do, escape out of the sides of the revolver at that pesky cylinder gap.

Additionally, if the chamber does not precisely align with the barrel due to the cylinder timing being off, some loathsome metal particles may come out of the side as well. The hot gases and particles that come out have a surprising amount of energy, even on a small revolver, and can cause some serious injury.

Demonstrating the incorrect manner of holding a revolver when shooting
If a new shooter tries to shoot a handgun that is too heavy for them, they might compensate for the weight in this manner which could cause tremendous damage.

That is why you want to ensure that you do not place any part of your hand or body ahead of the cylinder. Even standing too close to the side of the person firing the revolver could cause injury. I would extend this warning to standing at the rear on either side, at such an angle that particles, lead, or copper jacket shavings can deflect off the frame and bounce back to hit you from an out-of-time cylinder. I have had copper jacket shavings embedded in my cheeks from that very type of occurrence. That is also one of the main motivational reasons to wear eye protection.

Incorrect Grip

I have included some images demonstrating the correct ways to hold a revolver. Notice that in the correct cases, the person ensures that the hands are placed well behind the cylinder gap. Now, because I know some of you will do it, we will look at the incorrect ways to hold a revolver also.

In the first incorrect image, we see how not to hold the revolver. Never do this. Notice that the user has some fingers placed in front of the cylinder. This is a very bad idea and will result in serious injury, if the revolver is fired. People who are new to revolvers may accidentally do this because they find it easier to support a heavy revolver or because they see people doing it with pistols, and they cause injury to themselves.

Shooting a Kimber .357 Magnum revolver incorrectly
Even a small revolver can be problematic for new shooters regarding the cylinder gap.

The next photo was how yours truly learned his lesson the hard way about the dangers of cylinder gap. I thought I knew how dangerous and painful it could be. I was wrong. There was a time when I did lots of pistol shooting and hunting. To test myself, I would use a .357, .41 Mag. Or .44 Mag. to shoot everything from coyotes to bears but the most fun was shooting jackrabbits.

I used to walk the desert to sneak up on them. If they took off, I would shoot them on the run. It was great fun, but it was more fun to try to spot them at distance and snipe them with the revolver. One day, I decided to use some shooting sticks that my friend Herb Brusman developed.

Shooting a revolver using shooting sticks to show the dangers
Be careful when using a revolver with shooting sticks. Ensure your hand is behind the “gap.”

Well, I found an unsuspecting jack sitting about 100 yards out. I took a knee for a steady firing position. While holding the sticks with my off-hand, I supported the barrel on the sticks and fired.

The world went black! I saw stars and my hand went numb. I learned a very important and hard lesson — Never put anything you value in front of the cylinder gap.

And if you don’t want to take my word for it, look at the photo of gas escaping as it demonstrates pretty well why you should. See how much gas can come out of the sides of the cylinder and why it is a bad idea to put any body parts close to the cylinder gap? In fact, people standing close to the sides of the revolver may feel the hot gases as well. These are all good reasons why it is best to stand a good distance away from the shooter and ‘Respect the Gap!’

Do you have a ‘Respect the Gap’ story? Share it in the comment section.

  • Ed LaPorta wearing camouflage clothing while hunting jack rabbits
  • demonstrating the proper grip when shooting a revolver
  • Shooting a revolver using shooting sticks to show the dangers
  • Shooting a Kimber .357 Magnum revolver incorrectly
  • Demonstrating the incorrect manner of holding a revolver when shooting
  • cylinder gap of a revolver as it is being fired showing the hot dog exploding
  • hot dog held next to the cylinder gap of a revolver as it is being fired
  • Fire from the cylinder gap of a revolver
  • cylinder gap of a much used Smith & Wesson Model 57 in .41 Remington Magnum
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Comments (22)

  1. Warning also applies to revolver based rifles and long-barreled revolver with rifle stocks. Number of Colt rifle reproductions and copies have been produced over the years. Some of the newer ones have deflector covers to protect your leading forearm while in firing position but many don’t.

  2. Another great article Ed. I was first shown (visually) how vicious escaping gas can be by our club’s president many moons ago. He held a cardstock paper target to the side of a .44 and fired. I often show new shooters this if i feel they dont understand fully a verbal warning.

    One question after two points…
    Many say it is unsafe to grasp a pistol at the front of the slide during a reload as it increases the likelihood of exposing fingers to the trajectory of a bullet…. AND i know many shooters like to close their revolvers using the crane. So my question is… whats worse: grasping the front of an automatics slide which is still in keeping ones soft parts behind the danger zone, or closing a revolver with the crane?
    😁
    Yes, i am intentionally trying to stir a pot here.
    Cheers. Keep these great articles coming.

  3. Just another reason to know your weapon(s) like the back of your hand….or you just might lose that hand or parts thereof. Another intriguing and informative article by Ed LaPorta. Keep em coming
    bro….love them all!

  4. Hahaha yeah, I saw a coyote at the edge of the woods at roughly 75 yards. I had a Ruger Blackhawk 357. To steady my shot a got down to the Creedmoor position and took my shot. Missed the coyote but blew a hole in my pants leg the size of a half dollar. I was trying to get the shot off before he got into the woods, wasn’t even thinking about where the front of the cylinder was. Never did that again!

  5. Thanks a bunch … been thinking of getting a small revolver and so relieved to find out about cylinder gap and side fire. I promise not to learn the hard way thanks to your article.

  6. I would like to know how much pressure is lost through the cylinder gap for various models and calibers.

  7. @Ed, good read, sir. Thankfully I’ve never had any issue or injury from cylinder gap. Grew up shooting revolvers so it was non-issue… but when I was rangemaster/instructor there were some close calls on the line with some new recruits even though each time there had been an 8hr classroom session on safe handling, operation, etc. with each recruit required to demonstrate proper handling before stepping foot on range with live ammo. Luckily I was able to catch them BEFORE these folks managed to blow off digits. Depspite being shown, and them demonstrating proper handling some just weren’t up to the task of being anywhere near a loaded firearm. I’m pretty sure of these folks would’ve been capable of turning a marshmallow into a dealy weapon.

  8. @Phil, Assuming your revolver is in good working order there’s nothing to worry about safety wise with shooting .38 Spl out of a .357 chambered firearm. Power will be less because obviously there is less powder. Average of around 200-300 FPS less when using +P and around 400 +/- FPS less when using standard pressure .38 Spl. Accuracy is more or less not even worth mentioning. Point of aim MIGHT be slightly different and that’s all. In fact, a fair amount of people are MORE accurate on targets using .38 Spl in .357 chambered revolvers because of the lighter recoil. When I first started in law enforcement we were issued the S&W 686 with 4″ barrels. This is chambered in .357 but we weren’t allowed to use .357… we were issued .38 Spl +P. Our range ammo was standard pressure 158gr .38 Spl. Later on I became one our range masters/instructors and our 2nd armorer… honsetly using the standard and +P in the 686 made no practical difference in accuracy whatsoever. At real world distances on standard man sized targets during qualifications and shooting drills generally speaking even using the same sight picture hits were still within the X-ring. Unless you’re bench shooting for accuracy at 100yds I seriously doubt you’ll ever notice the difference… unless of course you’re Ed and popping jackrabbits on the run or sniping them at 100 yds.

  9. I blew open my thumb with a .44 Magnum by not paying attention to the gap. I knew better but was just not focusing as I should have been. My new SW 500 would really do some damage..

  10. Biggest disadvantage of revolvers can be the cylinder gap. Too great, and too much powder/power is lost. Not large enough, and as little as a single cylinder load will foul up the action. The reference to a “business card”, which is ~0.003″ thick, is almost the ideal size gap for nearly all current revolver cartridges. HOWEVER, the buildup of residue, (unburnt powder & bullet lead residue), on the forcing cone can be as big, or maybe a bigger issue, than the cylinder gap. Revolvers are ideal for shooting cast lead bullets but will lead up the forcing cone quickly. With any handgun, the SECOND thing one buys is a good cleaning kit, then ammo, spare magazine(s), and lastly a good holster. Modern ammo means that a handgun doesn’t have to be spotlessly cleaned every time it is shot, but any cleaning is a worthwhile endeavor.

  11. Great article, and pointing out the hazards of the gap. One other safety point of a single action revolver is; NEVER FAN A STANDARD SINGLE ACTION REVOLVER (especially your brand new one). I know they do in movies, and the cowboy shooters do too, but the cowboys are modified to do so. My first gun was a very low end single action .22/.22 Mag which I paid something like $18 new, decades ago. Like in the movies, I fanned it one day at the range. What I learned was fanning can put a revolver out of time, meaning when they fire, the cylinder may not be lined up with the bore, nor locked, before the powder goes off, resulting in the actual bullet partially hitting the frame, and some going down the barrel, spitting a lot of lead to the sides through that cylinder gap. That puts a tremendous strain on the frame, and cylinder parts, and in my case totally ruined my first brand new gun, which I ended up sawing in half, so no one would ever get hurt from it. I am happy I learned that lesson, but wish it had not been the hard way, so passing that info on.

  12. Some years ago, a fellow sued Smith and Wesson because the cylinder gap spray from a .500 cut off the tip of his left index finger. I did not hear the result of the suit. You know, we’d call him an idiot, but it really isn’t intuitive to respect that gap without some good training. I trained my young grandson by placing a plastic bag over a .22 revolver and firing it. The bag was shredded, of course. Stay safe.

  13. I can verify the dangers & learned a painful lesson.
    My father was shooting a new pistol (Taurus raging bull .454) & I leaned forward at the bench as he squeezed off a round. It took my safety glasses off & left 3 painful pin holes on my cheek.
    I have grown up shooting revolvers & never thought that standing 4 – 5 feet to the side of one would be that dangerous.

  14. What a great read… thanks for having the humility to teach others of what can go wrong. Muscle memory is a very serious thing and the reason why we train, so that when those stressful moments are in front of, and the gray matter is busy processing other inputs, the other pieces/ parts are doing what they’ve been taught. As a semi-auto guy in my older years, the last time I shot a revolver I was 18… after contemplating the content here, I’m convinced that given a (high caliber) revolver today, there would be a good chance those semi-auto muscle memories could have stepped in and chaos would have ensued. Well done sir, well done indeed!

  15. Thanks for the great article! I am reminded of the signs that are all around the London tube (subway) stops: MIND THE GAP! This sign is there because over the years the station platforms have, in many cases, moved away from the rails, leaving a gap between the platform and the car. These gaps are a hazard, and can cause tripping or turning / breaking of an ankle. Seems to me the signs apply to the Cylinder Gap, as well.

    And fortunately for me, I first learned to shoot with my father’s S&W .38 Detective Special, and he taught me how to hold it; as a physician, I guess he appreciated the hazards that your hotdog pictures illustrate. So when I shoot my S&W 929,I Mind the Gap!

  16. I love revolvers, never malfunctioned on me, small revolver is easier to carry than a small pistol, and revolver is technically alway ready, no need to take an extra step (like: rack a pistol slide).
    I am very thankful to read this article, Ed, instead of learning the cylinder gap dangers on my own hands. Always learn something new and your stories are entertaining!
    Thank you.

  17. A few years ago I took my daughter to the gun range to shoot some of my pistols. She was in the Security Forces of the US Air Force, so I knew she could handle anything well. After all, she had shot pistols, rifles, grenade launchers, and 50 cal. machine guns in training. But, I didn’t think about her pistol training having been only with the Beretta M9 and didn’t think to mention the cylinder gap on my S&W Model 10 short barrel revolver. In holding the revolver much as she did a semi-auto, she burnt her thumbs and some fingers a bit, but fortunately it was nothing serious. It could have been a lot worse. I learned that day to always tell someone about watching the cylinder gap.

  18. Very interesting! I’ve always wondered about shooting.38 from a .357 as well. The effects on accuracy, power and safety? Maybe for another article?

  19. When I first started following your articles I imagined that they would come to a stop at some point because after all…how much more is there to learn? Well I was wrong and besides learning from focus of the specific article it dawned on me that if I am going to own and use a gun I better be prepared to spend the time necessary to enjoy the benefits and keel myself and others safe. Thanks again Ed.

  20. I am able to verify the danger of a finger over the cylinder gap. When I was in the ninth grade the track coach asked me to start a race with a .22 starting pistol (.22 short blanks). I still bear the scar on my left thumb. If he had only told me, it would not have been so painful. I can only imagine what the damage would be with the larger calibers.

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