Hi, Tuner and guys,
Yes, I decided a new thread might be a good idea.
First, let me say that I have a lot of respect for Jerry Kuhnhausen, although I have never met him. I have, I think, all of his books, and generally the information can be taken to the bank. In fact, some of the information I post here is from those books; I try to give credit when the information is available only in a specific book (that is, is not general knowledge), and do so with Mr. Kuhnhausen's books as well. When I have a technical problem, or a question about specifications or fitting parts, Kuhnhausen is my guide. There is none better. My only regret is that when I was doing the work, I did not have all the nice tools he has.
All that being said, his explanation of the way a 1911 type pistol operates is, to put it mildly, somewhat flawed. In his illustrations, and in the accompanying text, he states that the barrel/slide unit does not begin to move until the bullet is out of the barrel. That is simply not true; if it were, the pistol would not work. The barrel begins to move the instant the bullet begins to move. The barrel remains locked to the slide until the bullet is out the barrel, at which point it has recoiled about 1/10 inch. This has been shown repeatedly in high speed films.
His explanation of a "thrust vector" (Vol. II, Page 42, Figure 4 caption) is nonsense, as is a lot of Para 5, Page 38.
So what really happens? And how does the pistol work? First, if you don't believe in the laws of physics, go to another thread.
The answer is recoil. This is sometimes couched in terms of Newton's Third Law, "for every action there is an equal and opposite reaction." That law is now called the Law of Conservation of Momentum, but the idea is the same. When the bullet moves forward, the part of the gun in contact with the bullet, the barrel, moves back. Is pressure involved? Of course, pressure is what moves the bullet. But pressure does not directly cause the gun to function in a recoil operated pistol as it does in a blowback pistol. (No, the pistol is not kept locked by the bullet pushing forward on the barrel; that force is essentially negligible.)
The bullet's forward motion causes the barrel's rearward motion, and it is that barrel motion that shoves the slide back (through the locking lugs and the hood) and operates the pistol. Now here is where it gets interesting. If the bullet does not move, the barrel does not recoil and the gun does not cycle, period. If the barrel is blocked directly ahead of the bullet, so the bullet cannot move, the gun will not operate. It remains locked, the pressure leaks away, and nothing happens. No, the gun does not "blow up"; the cartridge case does not explode. Nothing happens. (Yes, I have done it, but under tightly controlled conditions; please do not destroy a pistol or hurt yourself trying this.)
So, if the barrel/slide begins to move when the bullet does, when does the barrel unlock from the slide? That happens after the bullet has left the barrel and pressure has dropped to a safe level. Because the bullet is much lighter (has less mass) than the slide/barrel combination, it moves 4 inches or so, while the barrel/slide has moved only 1/10 inch or so.
That movement is the distance the barrel moves before the barrel foot slips off the slide stop pin, the barrel engages the link and begins linkdown. Until that happens, the barrel and slide are locked to withstand the high pressure in the barrel. By the time the unlocking takes place, the bullet has left the barrel and pressure has dropped. Note that the barrel is (or should be) kept locked by the barrel foot riding on the slide stop pin, not by the link.
OK, how does that affect some other fond ideas? Doesn't the recoil spring keep the barrel and slide locked? Well, no. A strong recoil spring can slow down the slide after it unlocks, but no reasonable spring can keep the recoil from shoving the slide back, only mass can do that, and no spring of reasonable weight is massive enough. In fact, the pistol will function and lock for the same amount of time whether a recoil spring is present or not. (Without one, however, the slide will batter the frame, since there is nothing to slow it down. (Yes, I have done this, too. Same warning!)
Does a recoil buffer help? It helps cushion the contact between the slide and the recoil spring guide/frame, and gives some people peace of mind that the frame is not being pounded. But steel is highly elastic, and the pistol is designed to allow the slide to bounce off the frame and use some of the recovered recoil energy in the forward part of the cycle. That is why installing a recoil buffer often results in failures to feed; not enough of the slide's energy is returned to assist the forward part of the cycle. (Remember those little steel balls in the rack that bounced for a long time once started? Put a buffer between them and the bouncing will soon stop.)
Doesn't the link lock the barrel back to the slide? No. The barrel foot is made to cam up on the slide stop pin. The gun can be fired without the link; it will not unlock consistently, since gravity is not that reliable in the circumstances, but return to battery is no problem. (Same again, same warning!)
So, Tuner and guys, have at it. I know there will be tons of argument about what I have written, but your significant others will thank me for distracting you and letting them get some sleep.
Jim
Yes, I decided a new thread might be a good idea.
First, let me say that I have a lot of respect for Jerry Kuhnhausen, although I have never met him. I have, I think, all of his books, and generally the information can be taken to the bank. In fact, some of the information I post here is from those books; I try to give credit when the information is available only in a specific book (that is, is not general knowledge), and do so with Mr. Kuhnhausen's books as well. When I have a technical problem, or a question about specifications or fitting parts, Kuhnhausen is my guide. There is none better. My only regret is that when I was doing the work, I did not have all the nice tools he has.
All that being said, his explanation of the way a 1911 type pistol operates is, to put it mildly, somewhat flawed. In his illustrations, and in the accompanying text, he states that the barrel/slide unit does not begin to move until the bullet is out of the barrel. That is simply not true; if it were, the pistol would not work. The barrel begins to move the instant the bullet begins to move. The barrel remains locked to the slide until the bullet is out the barrel, at which point it has recoiled about 1/10 inch. This has been shown repeatedly in high speed films.
His explanation of a "thrust vector" (Vol. II, Page 42, Figure 4 caption) is nonsense, as is a lot of Para 5, Page 38.
So what really happens? And how does the pistol work? First, if you don't believe in the laws of physics, go to another thread.
The answer is recoil. This is sometimes couched in terms of Newton's Third Law, "for every action there is an equal and opposite reaction." That law is now called the Law of Conservation of Momentum, but the idea is the same. When the bullet moves forward, the part of the gun in contact with the bullet, the barrel, moves back. Is pressure involved? Of course, pressure is what moves the bullet. But pressure does not directly cause the gun to function in a recoil operated pistol as it does in a blowback pistol. (No, the pistol is not kept locked by the bullet pushing forward on the barrel; that force is essentially negligible.)
The bullet's forward motion causes the barrel's rearward motion, and it is that barrel motion that shoves the slide back (through the locking lugs and the hood) and operates the pistol. Now here is where it gets interesting. If the bullet does not move, the barrel does not recoil and the gun does not cycle, period. If the barrel is blocked directly ahead of the bullet, so the bullet cannot move, the gun will not operate. It remains locked, the pressure leaks away, and nothing happens. No, the gun does not "blow up"; the cartridge case does not explode. Nothing happens. (Yes, I have done it, but under tightly controlled conditions; please do not destroy a pistol or hurt yourself trying this.)
So, if the barrel/slide begins to move when the bullet does, when does the barrel unlock from the slide? That happens after the bullet has left the barrel and pressure has dropped to a safe level. Because the bullet is much lighter (has less mass) than the slide/barrel combination, it moves 4 inches or so, while the barrel/slide has moved only 1/10 inch or so.
That movement is the distance the barrel moves before the barrel foot slips off the slide stop pin, the barrel engages the link and begins linkdown. Until that happens, the barrel and slide are locked to withstand the high pressure in the barrel. By the time the unlocking takes place, the bullet has left the barrel and pressure has dropped. Note that the barrel is (or should be) kept locked by the barrel foot riding on the slide stop pin, not by the link.
OK, how does that affect some other fond ideas? Doesn't the recoil spring keep the barrel and slide locked? Well, no. A strong recoil spring can slow down the slide after it unlocks, but no reasonable spring can keep the recoil from shoving the slide back, only mass can do that, and no spring of reasonable weight is massive enough. In fact, the pistol will function and lock for the same amount of time whether a recoil spring is present or not. (Without one, however, the slide will batter the frame, since there is nothing to slow it down. (Yes, I have done this, too. Same warning!)
Does a recoil buffer help? It helps cushion the contact between the slide and the recoil spring guide/frame, and gives some people peace of mind that the frame is not being pounded. But steel is highly elastic, and the pistol is designed to allow the slide to bounce off the frame and use some of the recovered recoil energy in the forward part of the cycle. That is why installing a recoil buffer often results in failures to feed; not enough of the slide's energy is returned to assist the forward part of the cycle. (Remember those little steel balls in the rack that bounced for a long time once started? Put a buffer between them and the bouncing will soon stop.)
Doesn't the link lock the barrel back to the slide? No. The barrel foot is made to cam up on the slide stop pin. The gun can be fired without the link; it will not unlock consistently, since gravity is not that reliable in the circumstances, but return to battery is no problem. (Same again, same warning!)
So, Tuner and guys, have at it. I know there will be tons of argument about what I have written, but your significant others will thank me for distracting you and letting them get some sleep.
Jim