Driftwood Johnson
Member
Howdy Again
Let's talk about firing pins for a moment.
This is the hammer of a 2nd Gen Colt Single Action Army. Remember I mentioned 'cushioning' a little bit ago? When most firearms are dry fired, that is to say without a live cartridge or snap cap under the hammer, the hammer slams to a stop against the frame of the firearm. Remember the old story of the guy who fell off the Empire State Building, and when he passed the 50th floor somebody heard him say, 'so far so good'? It's not the fall that kills, its the short stop at the end. That is an apt illustration of what happens when the hammer slams into the frame of a revolver, or any other firearm. In terms of deceleration, the G forces exerted on the hammer, and particularly the firing pin, approach infinity. Those are the same G forces we talk about that fighter pilots endure in a high speed dive, or astronauts experience when a rocket takes off. A fighter pilot can experience 8 or 9 Gs (the G stands for Gravity), wearing a pressure suit. Many years ago I worked for an electronics company that made military grade electronics. Those parts would be subjected to acceleration to test how much abuse they could take. We would test the parts under hundreds of Gs. One of the engineers told me back then that when an object falls to the ground and comes to a sudden stop, the G forces of deceleration are almost infinite.
What does all of this have to do with firing pins? Notice the shape of the firing pin on this Colt hammer. It tapers to a long, thin section. If the hammer is dropped, without a primer or snap cap to cushion the blow, the tip of the firing pin wants to keep right on going. The red line I drew across the firing pin shows where the tip would break off as the tip kept right on going. Yes, I have seen it happen. Not often, but it does happen. That is why I never dry fire my Colts, with firing pins shaped like this.
Here is the hammer of a S&W Model 14-3. Yes, S&W prefers to call the firing pin a hammer nose, but for our purposes let's call it a firing pin. Notice the long this shape of the firing pin. I have drawn a line across the firing pin where it would probably break off if dry fired a bazillion times. Yes, the S&W firing pin is held in place with a rivet, and that probably provides a small amount of cushioning if the hammer slams against the frame with nothing to cushion the blow. No, it is not going to be guaranteed to break off right away, but snap the hammer on an empty chamber enough times and you are asking for trouble.
This is the hammer from an antique Smith and Wesson Schofield revolver. The firing pin is an integral part of the hammer, machined from the same block of steel. So unlike the more modern firing pins, which can be replaced in the hammer, if this one breaks, you are going to either have to find a new hammer, or weld up a new firing pin tip to replace what broke off. No way I would ever dry fire this revolver.
So what does all this have to do with the firing pin on a modern S&W 22 Rimfire revolver? This is the firing pin assembly in my Model 617-6. The firing pin slips into the hole in the frame, and the retaining pin goes into the other small hole, so that it fits into the slot cut in the firing pin. The retaining pin is held in place when the side plate is secured to the frame. But what else do we have here? A small coil rebound spring. The spring keeps the firing pin retracted in the frame, so the cylinder can be opened without the firing pin interfering with a cartridge in the cylinder when the cylinder is opened of closed. When the hammer smacks the firing pin, as the firing pin is driven forward it compresses the little spring, allowing the firing pin to travel forward and strike a primer. And yes, the little spring will provide a small amount of cushioning if the hammer is dropped on an empty chamber without a live round or snap cap in the chamber. Also, I expect some energy is lost as the hammer strikes the firing pin, further reducing the stress on the narrow portion of the firing pin. As I said previously, at least I think I did, if the hammer is dropped on a S&W 22 RF revolver on an empty chamber, the firing pin will not strike the cylinder, and I sincerely doubt if the tip of the firing pin will separate. Of course, I am not going to try it a bazillion times, that could be asking for trouble. But I doubt if dry firing a S&W 22 rimfire revolver a few times is going to hurt anything. Even if the tip of the firing pin separated, look how simple it would be to replace the firing pin. One cannot say that for any of the other hammers I have posted photos of here.
Let's talk about firing pins for a moment.
This is the hammer of a 2nd Gen Colt Single Action Army. Remember I mentioned 'cushioning' a little bit ago? When most firearms are dry fired, that is to say without a live cartridge or snap cap under the hammer, the hammer slams to a stop against the frame of the firearm. Remember the old story of the guy who fell off the Empire State Building, and when he passed the 50th floor somebody heard him say, 'so far so good'? It's not the fall that kills, its the short stop at the end. That is an apt illustration of what happens when the hammer slams into the frame of a revolver, or any other firearm. In terms of deceleration, the G forces exerted on the hammer, and particularly the firing pin, approach infinity. Those are the same G forces we talk about that fighter pilots endure in a high speed dive, or astronauts experience when a rocket takes off. A fighter pilot can experience 8 or 9 Gs (the G stands for Gravity), wearing a pressure suit. Many years ago I worked for an electronics company that made military grade electronics. Those parts would be subjected to acceleration to test how much abuse they could take. We would test the parts under hundreds of Gs. One of the engineers told me back then that when an object falls to the ground and comes to a sudden stop, the G forces of deceleration are almost infinite.
What does all of this have to do with firing pins? Notice the shape of the firing pin on this Colt hammer. It tapers to a long, thin section. If the hammer is dropped, without a primer or snap cap to cushion the blow, the tip of the firing pin wants to keep right on going. The red line I drew across the firing pin shows where the tip would break off as the tip kept right on going. Yes, I have seen it happen. Not often, but it does happen. That is why I never dry fire my Colts, with firing pins shaped like this.
Here is the hammer of a S&W Model 14-3. Yes, S&W prefers to call the firing pin a hammer nose, but for our purposes let's call it a firing pin. Notice the long this shape of the firing pin. I have drawn a line across the firing pin where it would probably break off if dry fired a bazillion times. Yes, the S&W firing pin is held in place with a rivet, and that probably provides a small amount of cushioning if the hammer slams against the frame with nothing to cushion the blow. No, it is not going to be guaranteed to break off right away, but snap the hammer on an empty chamber enough times and you are asking for trouble.
This is the hammer from an antique Smith and Wesson Schofield revolver. The firing pin is an integral part of the hammer, machined from the same block of steel. So unlike the more modern firing pins, which can be replaced in the hammer, if this one breaks, you are going to either have to find a new hammer, or weld up a new firing pin tip to replace what broke off. No way I would ever dry fire this revolver.
So what does all this have to do with the firing pin on a modern S&W 22 Rimfire revolver? This is the firing pin assembly in my Model 617-6. The firing pin slips into the hole in the frame, and the retaining pin goes into the other small hole, so that it fits into the slot cut in the firing pin. The retaining pin is held in place when the side plate is secured to the frame. But what else do we have here? A small coil rebound spring. The spring keeps the firing pin retracted in the frame, so the cylinder can be opened without the firing pin interfering with a cartridge in the cylinder when the cylinder is opened of closed. When the hammer smacks the firing pin, as the firing pin is driven forward it compresses the little spring, allowing the firing pin to travel forward and strike a primer. And yes, the little spring will provide a small amount of cushioning if the hammer is dropped on an empty chamber without a live round or snap cap in the chamber. Also, I expect some energy is lost as the hammer strikes the firing pin, further reducing the stress on the narrow portion of the firing pin. As I said previously, at least I think I did, if the hammer is dropped on a S&W 22 RF revolver on an empty chamber, the firing pin will not strike the cylinder, and I sincerely doubt if the tip of the firing pin will separate. Of course, I am not going to try it a bazillion times, that could be asking for trouble. But I doubt if dry firing a S&W 22 rimfire revolver a few times is going to hurt anything. Even if the tip of the firing pin separated, look how simple it would be to replace the firing pin. One cannot say that for any of the other hammers I have posted photos of here.
