Don't drop slide or will ruin sear?
- Thread starter Banzai
- Start date
OK, let's make sure I understand you. You know more than Jerry Kuhnhausen about the 1911? It's odd that I never hear your name mentioned when people talk about 1911 experts.
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Isn't he the fellow who says the bullet exits the barrel and the pressure drops to zero before the action begins to open? His pistol may work that way, mine doesn't.[/quote]
Actually, he says the barrel and slide don't unlock until the bullet leaves the barrel. I'd be a bit surprised if your slide moves enough to unlock the barrel/slide before the bullet leaves the barrel. Are you sure your gun is really a 1911?
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Isn't he the fellow who says the bullet exits the barrel and the pressure drops to zero before the action begins to open? His pistol may work that way, mine doesn't.[/quote]
Actually, he says the barrel and slide don't unlock until the bullet leaves the barrel. I'd be a bit surprised if your slide moves enough to unlock the barrel/slide before the bullet leaves the barrel. Are you sure your gun is really a 1911?
Golly, Johnwill, I think it is a 1911, but I could be wrong, being so ignorant.
Kuhnhausen is very good at working on 1911 type pistols and his books are invaluable to anyone, myself included.
But the other JK shows a pistol with the bullet leaving the barrel (Fig. 30 in my Vol. 2) and says that bullet exit drops the pressure to zero. This is not true, there is still some residual pressure, but let that go for a moment. At that point, he shows the barrel and slide fully locked and in battery.
In fact, the barrel and slide, locked together, begin to move at the same instant the bullet does. The forward motion of the bullet (not gas pressure) produces the equal and opposite reaction of moving the barrel-slide unit backward. The barrel-slide unit is more massive and does not move as fast as the bullet but it does begin to move at that time. Backward pressure on the cartridge case is not a factor, because it is pushing against the slide, which is immovable relative to the barrel at this point.
The barrel-slide unit picks up momentum as the bullet moves down the barrel and when the bullet exits has already begun to unlock.
The momentum carries the barrel and slide back until the barrel drops and unlocks fully from the slide, at which time the slide retains enough momentum to complete compression of the recoil spring, cock the hammer, and prepare to feed another round.
The slide is not propelled forward only by the energy stored in the recoil spring, but also by some of its backward momentum stored when it impacts and bounces off the recoil spring guide. This results in the slide moving forward after firing much faster than it would move under spring energy alone, which gets us back to the question of the rapidity with which the hammer drops on the sear.
Note that it is not (contrary to Fig. 29) the gas pressure itself that causes the pistol to function, it is the motion of the bullet.
In a recoil operated pistol (unlike a blowback) nothing will happen unless the bullet moves. This can be proven (and has been) by plugging up the barrel, leaving just enough room for the cartridge, and then firing the gun. The bullet can't move and the gun will not open. The gas pressure will leak out over time, but the gun will stay locked.
That is the difference between a recoil operated pistol (whether Browning type or another design) and a blowback pistol, where the operation is done solely by gas pressure. Blocking the barrel on a blowback pistol is not recommended.
As to my "fame" or lack of it, my inherent modesty precludes comment.
HTH
Jim
Kuhnhausen is very good at working on 1911 type pistols and his books are invaluable to anyone, myself included.
But the other JK shows a pistol with the bullet leaving the barrel (Fig. 30 in my Vol. 2) and says that bullet exit drops the pressure to zero. This is not true, there is still some residual pressure, but let that go for a moment. At that point, he shows the barrel and slide fully locked and in battery.
In fact, the barrel and slide, locked together, begin to move at the same instant the bullet does. The forward motion of the bullet (not gas pressure) produces the equal and opposite reaction of moving the barrel-slide unit backward. The barrel-slide unit is more massive and does not move as fast as the bullet but it does begin to move at that time. Backward pressure on the cartridge case is not a factor, because it is pushing against the slide, which is immovable relative to the barrel at this point.
The barrel-slide unit picks up momentum as the bullet moves down the barrel and when the bullet exits has already begun to unlock.
The momentum carries the barrel and slide back until the barrel drops and unlocks fully from the slide, at which time the slide retains enough momentum to complete compression of the recoil spring, cock the hammer, and prepare to feed another round.
The slide is not propelled forward only by the energy stored in the recoil spring, but also by some of its backward momentum stored when it impacts and bounces off the recoil spring guide. This results in the slide moving forward after firing much faster than it would move under spring energy alone, which gets us back to the question of the rapidity with which the hammer drops on the sear.
Note that it is not (contrary to Fig. 29) the gas pressure itself that causes the pistol to function, it is the motion of the bullet.
In a recoil operated pistol (unlike a blowback) nothing will happen unless the bullet moves. This can be proven (and has been) by plugging up the barrel, leaving just enough room for the cartridge, and then firing the gun. The bullet can't move and the gun will not open. The gas pressure will leak out over time, but the gun will stay locked.
That is the difference between a recoil operated pistol (whether Browning type or another design) and a blowback pistol, where the operation is done solely by gas pressure. Blocking the barrel on a blowback pistol is not recommended.
As to my "fame" or lack of it, my inherent modesty precludes comment.
HTH
Jim
Jim,
Not to pour fuel on a potential fire, but I'm trying to understand the physics (okay, I flunked it) here.
Wouldn't the action of stripping a new round from the magazine and then chambering the new round bleed off/negate the rebound speed of the slide that you mention?
If so, isn't it possible that the slide would then be moving more slowly than one dropped from locked back position by spring pressure alone (assuming an empty chamber/no round to feed)?
It seems that dropping the slide on a empty chamber results in a faster movement than chambering a round from the mag with the slide locked back. Obviously I can't actually see a difference, but the perception of feel and hearing is that this is so.
If the slide is actually moving more slowing chambering a round, then my (probably faulty) logic makes me think that the stress on the hammer/sear interface could also be less.
Unless of course you were speaking about the slide closing on an empty chamber in both instances, in which case this entire post has been a big waste of bandwidth.
Then again, with a hammer/sear interface set to Mr. Browning's specs, I kinda doubt it'll make much difference anyway.
Bimjo (ramblin' again)
Not to pour fuel on a potential fire, but I'm trying to understand the physics (okay, I flunked it) here.
Wouldn't the action of stripping a new round from the magazine and then chambering the new round bleed off/negate the rebound speed of the slide that you mention?
If so, isn't it possible that the slide would then be moving more slowly than one dropped from locked back position by spring pressure alone (assuming an empty chamber/no round to feed)?
It seems that dropping the slide on a empty chamber results in a faster movement than chambering a round from the mag with the slide locked back. Obviously I can't actually see a difference, but the perception of feel and hearing is that this is so.
If the slide is actually moving more slowing chambering a round, then my (probably faulty) logic makes me think that the stress on the hammer/sear interface could also be less.
Unless of course you were speaking about the slide closing on an empty chamber in both instances, in which case this entire post has been a big waste of bandwidth.
Then again, with a hammer/sear interface set to Mr. Browning's specs, I kinda doubt it'll make much difference anyway.
Bimjo (ramblin' again)
Hi, Bimjo,
Yes, the action of picking up a round from the magazine slows down the slide in its forward motion, whether it is running forward after firing or just released by hand.
We all got a bit off the track on this one.
The hammer full cock notch drops on the sear when the slide moves out of the way. This action is the same regardless of whether the slide is dropping on an empty chamber or not, whether the gun has just fired or not. If the sear or hammer is damaged in one case, it will be damaged in any case.
But, with a very light trigger pull, another factor comes into play. When the slide is dropped, the barrel impacting on the slide stop pin brings the whole moving barrel-slide mass to a quick halt and jars the whole gun forward.
The 1911 trigger is free floating in the frame, so when the gun is jarred forward, the trigger tends to remain in place, moving rearward in respect to the frame. So in effect the trigger pulls itself. If the sear-hammer interface is not properly set up, the hammer will drop on the half cock notch. This will not normally damage a properly hardened and set up sear and hammer, but can damage an overly delicate one. (This does not happen in firing, because the trigger is being held to the rear.) This is the origin of the idea that dropping the slide is bad.
Obviously one can get around this by easing the slide down, or by holding back the trigger or hammer when releasing the slide. Other solutions, such as lightweight triggers (plastic or aluminum) can minimize the condition, which is the result of smiths going along with customer demand for ever lighter trigger pulls in what was intended as a military pistol.
I am not against easing the slide down. I am still saying that in a normal 1911 type pistol, there is no need to do so.
Jim
Yes, the action of picking up a round from the magazine slows down the slide in its forward motion, whether it is running forward after firing or just released by hand.
We all got a bit off the track on this one.
The hammer full cock notch drops on the sear when the slide moves out of the way. This action is the same regardless of whether the slide is dropping on an empty chamber or not, whether the gun has just fired or not. If the sear or hammer is damaged in one case, it will be damaged in any case.
But, with a very light trigger pull, another factor comes into play. When the slide is dropped, the barrel impacting on the slide stop pin brings the whole moving barrel-slide mass to a quick halt and jars the whole gun forward.
The 1911 trigger is free floating in the frame, so when the gun is jarred forward, the trigger tends to remain in place, moving rearward in respect to the frame. So in effect the trigger pulls itself. If the sear-hammer interface is not properly set up, the hammer will drop on the half cock notch. This will not normally damage a properly hardened and set up sear and hammer, but can damage an overly delicate one. (This does not happen in firing, because the trigger is being held to the rear.) This is the origin of the idea that dropping the slide is bad.
Obviously one can get around this by easing the slide down, or by holding back the trigger or hammer when releasing the slide. Other solutions, such as lightweight triggers (plastic or aluminum) can minimize the condition, which is the result of smiths going along with customer demand for ever lighter trigger pulls in what was intended as a military pistol.
I am not against easing the slide down. I am still saying that in a normal 1911 type pistol, there is no need to do so.
Jim
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Jim Keenan:
We all got a bit off the track on this one.
The hammer full cock notch drops on the sear when the slide moves out of the way. This action is the same regardless of whether the slide is dropping on an empty chamber or not, whether the gun has just fired or not. If the sear or hammer is damaged in one case, it will be damaged in any case.
[/quote]
Okay, thanks for the reply. The timing of the hammer engaging the sear is where it was getting fuzzy for me. Seemed like a slower slide would make a less jarring engagement.
Your explanation and a little hands-on with the actual item as a visual aid has made the light go on.
Bimjo
We all got a bit off the track on this one.
The hammer full cock notch drops on the sear when the slide moves out of the way. This action is the same regardless of whether the slide is dropping on an empty chamber or not, whether the gun has just fired or not. If the sear or hammer is damaged in one case, it will be damaged in any case.
[/quote]
Okay, thanks for the reply. The timing of the hammer engaging the sear is where it was getting fuzzy for me. Seemed like a slower slide would make a less jarring engagement.
Your explanation and a little hands-on with the actual item as a visual aid has made the light go on.
Bimjo