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.
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!
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.
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.
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?
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.
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.
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.
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.
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!’