How important is the Smith and Wesson "hammer block safety"???
- Thread starter lharrell79
- Start date
To try to make a long story short (see Pate for the long version with the documents)...
S&W was on the verge of bankruptcy in the 1930s. Tooling up for the war happened quickly and they had to hire hundreds of untrained workers. S&W also introduced cost and time saving measures to meet their war time contracts, some un-proven.They had problems with quality control during the war. As a result the Army set up rigid inspection procedures in insure quality. The Navy took for granted the high quality of the pre-war M&P revolvers and expected the same so they did not set up the same procedures. Later the Army would suspect the Navy was over-reacting to the problem. But then...
A M&P revolver fell from the hands of a seaman onto the steel deck of a ship. The total distance involved in the drop was only a few feet. The hammer was down (not cocked) on the weapon at the time of the drop.The gun fired and a Seaman was killed.
The gun was examined by the Bureau of Ordnance and found to be non tampered with and a standard revolver. "Primed cartridges were placed in the revolver and were discharged by dropping the revolver." according to a 1944 report reprinted in Pate. Meaning the dropped the guns from waist height and the primers went off.
Following these results of the initial inspection by the Navy Bureau of Ordnance 90 new in there box S&W revolvers as delivered to the Navy were unpacked, inspected and tested. An aluminum frame was built and one by one the guns were placed in this with the muzzles pointed at the ground. A brass weight was then dropped on rear of the hammer which was not cocked but at rest.
31 of the 90 guns discharged with a 2 pound weight falling 2 1/2 feet.
The majority of guns fired with a 2 pound weight falling 3 feet. This is less than waist height.
The Navy Dept. Bureau of Ordnance on May 6th 1944 said:
"As a result of these tests the Smith and Wesson, Military and Police, Caliber .38 Special Revolver as now being supplied is considered unsafe for issuance to Naval forces. To guard against recurrence of accidents as herein described, instructions are being issued to Naval activities not to carry a cartridge in the chamber under the hammer."
This latter bit was the first time any such order was given by the military and may be the source of the belief that it's unsafe to carry a da revolver with the hammer down on a live round.
The guns were examined and it was found that the cause or the problem was:
"a. The Block, Hammer, is harder than the Hammer and Frame of the Revolver;
b. When the Hammer spur is struck a sharp blow, the hardened Block, Hammer causes a sufficient indent of both hammer face and frame to permit firing the revolver."
At any rate The War department got involved the search for a repair began and were ordered.
This is a short version and Pate contains the documentation and pics.
tipoc
S&W was on the verge of bankruptcy in the 1930s. Tooling up for the war happened quickly and they had to hire hundreds of untrained workers. S&W also introduced cost and time saving measures to meet their war time contracts, some un-proven.They had problems with quality control during the war. As a result the Army set up rigid inspection procedures in insure quality. The Navy took for granted the high quality of the pre-war M&P revolvers and expected the same so they did not set up the same procedures. Later the Army would suspect the Navy was over-reacting to the problem. But then...
A M&P revolver fell from the hands of a seaman onto the steel deck of a ship. The total distance involved in the drop was only a few feet. The hammer was down (not cocked) on the weapon at the time of the drop.The gun fired and a Seaman was killed.
The gun was examined by the Bureau of Ordnance and found to be non tampered with and a standard revolver. "Primed cartridges were placed in the revolver and were discharged by dropping the revolver." according to a 1944 report reprinted in Pate. Meaning the dropped the guns from waist height and the primers went off.
Following these results of the initial inspection by the Navy Bureau of Ordnance 90 new in there box S&W revolvers as delivered to the Navy were unpacked, inspected and tested. An aluminum frame was built and one by one the guns were placed in this with the muzzles pointed at the ground. A brass weight was then dropped on rear of the hammer which was not cocked but at rest.
31 of the 90 guns discharged with a 2 pound weight falling 2 1/2 feet.
The majority of guns fired with a 2 pound weight falling 3 feet. This is less than waist height.
The Navy Dept. Bureau of Ordnance on May 6th 1944 said:
"As a result of these tests the Smith and Wesson, Military and Police, Caliber .38 Special Revolver as now being supplied is considered unsafe for issuance to Naval forces. To guard against recurrence of accidents as herein described, instructions are being issued to Naval activities not to carry a cartridge in the chamber under the hammer."
This latter bit was the first time any such order was given by the military and may be the source of the belief that it's unsafe to carry a da revolver with the hammer down on a live round.
The guns were examined and it was found that the cause or the problem was:
"a. The Block, Hammer, is harder than the Hammer and Frame of the Revolver;
b. When the Hammer spur is struck a sharp blow, the hardened Block, Hammer causes a sufficient indent of both hammer face and frame to permit firing the revolver."
At any rate The War department got involved the search for a repair began and were ordered.
This is a short version and Pate contains the documentation and pics.
tipoc
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lharrell79
New member
That is really great information tipoc, that is exactly what I was looking for. So it appears that maybe the hammer, spur, and rebound slide aren't as robust as I previously thought. 31 out of 90 is not very good odds. 
Mike Irwin
Staff
Remember. It was war time and corners were being cut to expedite production. Smith also had QC problems during WWI to the point that the Army took over operations for much of US involvement.
From post #1...
Well I think you'll want to see a gunsmith about having the parts that are missing installed. S&W may also do it for you. The original parts from your 64-5 were good strong ones and good for the job.
Your gun was made decades after the 1944 problem was corrected.
tipoc
Well I think you'll want to see a gunsmith about having the parts that are missing installed. S&W may also do it for you. The original parts from your 64-5 were good strong ones and good for the job.
Your gun was made decades after the 1944 problem was corrected.
tipoc
lharrell79
New member
Tipoc, I've already got a hammer block safety coming in the mail. I will install it once it gets here.
Mike Irwin
Staff
During the crush for production during World War II Enfield and Webley revolvers were modified to omit the hammer block safety as a way of getting them made and into the hands of troops more quickly.
After the war most were recalled and refitted with the hammer block.
After the war most were recalled and refitted with the hammer block.
Driftwood Johnson
New member
Tipoc
I think you are a little bit confused about the configuration of the different types of hammer blocks Smith and Wesson has used over the years.
When Supica and Nahas mention
'a shoulder on the rebound slide which was forced against a shoulder on the hammer. These shoulders kept the hammer nose off the cartridge in the down position'
this is what they were talking about. This is the same photo I posted earlier of the 1908 vintage M&P. I have added two arrows, pointing to the two shoulders. I call them humps. There was no separate Hammer Block in revolvers of this vintage. The two opposing humps forced the hammer back so that the firing pin (Nahas and Supica use the term 'Hammer Nose' which is what S&W call a firing pin) was moved back away from the primer of a round under the hammer. You can see in this photo that the hammer is indeed forced back, the third arrow is pointing to a space between the hammer and the frame. I repeat, there was no separate Hammer Block in revolvers of this era. The two humps wedged the hammer back when the trigger was released, removing the firing pin away from a cartridge in the chamber under the hammer. These two humps have always been part of the design of every S&W swing out cylinder revolver since 1905. The actual shape and geometry of them has changed over time, but they are still part of the design, and they are the primary means of preventing a round under the hammer from firing. They have always been, ever since 1905. The various Hammer Block designs that have been incorporated over time are additional safety devices, designed to keep the revolver safe if the 'two humps' failed.
By the way, keep that space between the hammer and the frame in mind, it comes into play later.
I do not have a photo of the first type of Hammer Block that S&W incorporated in the design, Mike Irwin was kind enough to supply one.
You misquoted me calling the photo of the Hammer Block in the side plate as a 1926 era revolver. It is not. 1926 is when S&W started incorporating that type of Hammer Block.
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Here is a photo of another revolver with the second type of hammer block in it. This revolver was made in 1939. Don't look for a spring, the entire Hammer Block is a piece of spring steel. It is held in place in its slot at the very bottom where it has been peened to the side plate. You can see the tab on the side of the Hammer Block that rides against the ramp on the hand. This is the type of Hammer Block that failed in the Navy incident involving a Victory Model. You can also see in this photo that the 'two humps' although their shape has changed slightly, are still doing their job of keeping the hammer back.
I am reposting this photo because it shows the hammer block at a slightly different angle. In addition to the tab that rubs against the ramp on the hand, in this view you can see the 'business part' of the Hammer Block that fits into that space between the hammer and the frame.
**************
This is the type of Hammer Block that was designed after the Navy incident in 1944. It is the same type of Hammer block that is still in use in S&W revolvers today. This gun happens to be a Model 17 from 1975, but the Hammer Block is the same as was designed in 1944. It is the same type of Hammer Block that S&W still uses.
Notice that the Hammer Block gets pushed by a pin on the Rebound Slide. Notice too, that the 'two humps' are still doing their job, even though their shape has changed slightly. Notice also that the Hammer Block is in its upper position, sandwiched between the hammer and the frame. The hammer is not actually resting on the Hammer Block, there is a teeny bit of space between the hammer block and the hammer. But if the 'two humps' should fail, the Hammer Block is there to prevent the firing pin from striking a primer.
When the hammer is cocked, or the trigger is pulled, the Rebound Slide is pushed backwards. The slanted configuration of the slot in the Hammer Block causes the pin to pull the Hammer Block down diagonally in its slot, clearing the hammer so the gun can fire.
This is how the modern Hammer Block rides in its slot in the Side Plate.
Just for fun, here is a photo of the lockwork of a big N frame revolver, a 44 Hand Ejector 4th Model (Model of 1950 Target). This gun shipped in 1955. Even though the parts are bigger, they function the same way.
I hope this helps make the function of the various Hammer Blocks (and the lack of one) clear.
I think you are a little bit confused about the configuration of the different types of hammer blocks Smith and Wesson has used over the years.
When Supica and Nahas mention
'a shoulder on the rebound slide which was forced against a shoulder on the hammer. These shoulders kept the hammer nose off the cartridge in the down position'
this is what they were talking about. This is the same photo I posted earlier of the 1908 vintage M&P. I have added two arrows, pointing to the two shoulders. I call them humps. There was no separate Hammer Block in revolvers of this vintage. The two opposing humps forced the hammer back so that the firing pin (Nahas and Supica use the term 'Hammer Nose' which is what S&W call a firing pin) was moved back away from the primer of a round under the hammer. You can see in this photo that the hammer is indeed forced back, the third arrow is pointing to a space between the hammer and the frame. I repeat, there was no separate Hammer Block in revolvers of this era. The two humps wedged the hammer back when the trigger was released, removing the firing pin away from a cartridge in the chamber under the hammer. These two humps have always been part of the design of every S&W swing out cylinder revolver since 1905. The actual shape and geometry of them has changed over time, but they are still part of the design, and they are the primary means of preventing a round under the hammer from firing. They have always been, ever since 1905. The various Hammer Block designs that have been incorporated over time are additional safety devices, designed to keep the revolver safe if the 'two humps' failed.
By the way, keep that space between the hammer and the frame in mind, it comes into play later.
I do not have a photo of the first type of Hammer Block that S&W incorporated in the design, Mike Irwin was kind enough to supply one.
You misquoted me calling the photo of the Hammer Block in the side plate as a 1926 era revolver. It is not. 1926 is when S&W started incorporating that type of Hammer Block.
********************
Here is a photo of another revolver with the second type of hammer block in it. This revolver was made in 1939. Don't look for a spring, the entire Hammer Block is a piece of spring steel. It is held in place in its slot at the very bottom where it has been peened to the side plate. You can see the tab on the side of the Hammer Block that rides against the ramp on the hand. This is the type of Hammer Block that failed in the Navy incident involving a Victory Model. You can also see in this photo that the 'two humps' although their shape has changed slightly, are still doing their job of keeping the hammer back.
I am reposting this photo because it shows the hammer block at a slightly different angle. In addition to the tab that rubs against the ramp on the hand, in this view you can see the 'business part' of the Hammer Block that fits into that space between the hammer and the frame.
**************
This is the type of Hammer Block that was designed after the Navy incident in 1944. It is the same type of Hammer block that is still in use in S&W revolvers today. This gun happens to be a Model 17 from 1975, but the Hammer Block is the same as was designed in 1944. It is the same type of Hammer Block that S&W still uses.
Notice that the Hammer Block gets pushed by a pin on the Rebound Slide. Notice too, that the 'two humps' are still doing their job, even though their shape has changed slightly. Notice also that the Hammer Block is in its upper position, sandwiched between the hammer and the frame. The hammer is not actually resting on the Hammer Block, there is a teeny bit of space between the hammer block and the hammer. But if the 'two humps' should fail, the Hammer Block is there to prevent the firing pin from striking a primer.
When the hammer is cocked, or the trigger is pulled, the Rebound Slide is pushed backwards. The slanted configuration of the slot in the Hammer Block causes the pin to pull the Hammer Block down diagonally in its slot, clearing the hammer so the gun can fire.
This is how the modern Hammer Block rides in its slot in the Side Plate.
Just for fun, here is a photo of the lockwork of a big N frame revolver, a 44 Hand Ejector 4th Model (Model of 1950 Target). This gun shipped in 1955. Even though the parts are bigger, they function the same way.
I hope this helps make the function of the various Hammer Blocks (and the lack of one) clear.
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lharrell79
New member
Driftwood, which of the pictures you posted is the design of the failed Navy revolver? Do you have a picture of the hammer and rebound slide for this model?
Thanks
Thanks
Mike Irwin
Staff
Post 48. The second and third photographs.
Note that the rebound slide (S&W) and rebound lever (Colt) are not designed specifically as hammer blocks. They are designed to retract the hammer from the fired primer and allow the gun to be opened. A rebound mechanism was not needed in top break revolvers since rotating the barrel and cylinder away from the breech pushes a hammer-mounted firing pin back out of the way.
But in a swing cylinder revolver, the cylinder cannot be opened with the firing pin embedded in a fired primer, so if the firing pin is hammer mounted, it has to be made to rebound, otherwise it has to be put on half-cock, slowing down reloading.
Jim
But in a swing cylinder revolver, the cylinder cannot be opened with the firing pin embedded in a fired primer, so if the firing pin is hammer mounted, it has to be made to rebound, otherwise it has to be put on half-cock, slowing down reloading.
Jim
Driftwood Johnson
New member
So after all this chat about Victory Models, I remembered late last night that I have one. I never had the side plate off, so this was a good opportunity.
This gun shipped from the factory in October of 1943. This one was never refitted with the modern type Hammer Block, it still has the type that was in the gun that was involved in the incident on shipboard.
Extra points to those who notice the gun has been refinished.
This gun shipped from the factory in October of 1943. This one was never refitted with the modern type Hammer Block, it still has the type that was in the gun that was involved in the incident on shipboard.
Extra points to those who notice the gun has been refinished.
Jim Watson
New member
A number of top break revolvers HAVE rebounding hammers, presumably for safety's sake, since it is not needed to clear the action opening.
I don't know when H&R added the IJ style transfer bar, but those made in my lifetime have them.
Hopkins & Allen topbreak revolvers had an odd eccentric bearing cam for the hammer. Pulling the trigger actually lowered the hammer in the frame to hit the firing pin. At rest, the hammer was down against the frame away from the firing pin. Safe but complicated.
Driftwood Johnson
New member
Howdy Again
That is not really quite correct. At least with the large frame S&W Top Breaks, when the barrel rotates, there is enough vertical motion of the cylinder that if the firing pin is not withdrawn it will hang up in the dent in the primer of a fired cartridge as the barrel/cylinder assembly tries to rotate past. The other thing is when you close a Top Break you don't want the firing pin protruding through the recoil shield. Slam the gun closed hard enough, and you might fire a round.
For these reasons, all the S&W large frame Top Break revolvers that I am familiar with have a mechanism to make sure the firing pin has withdrawn before the frame can be unlatched.
The hammer of this Russian Model is all the way forward. Although the photo is a bit out of focus, you can see the firing pin protruding through the recoil shield. While in this position, the slot in the hammer has engaged a tab on the latch, preventing the latch from rotating up. With the latch locked down like this, the revolver cannot be broken open.
With the hammer rotated back to the 'half cock' loading position, the firing pin has been withdrawn and the slot in the hammer has cleared the tab on the latch, allowing the revolver to be broken open. This hammer position also lowers the bolt, allowing the cylinder to spin freely.
The Schofield Model had a different type of latch, but the arrangement of the hammer prevented the latch rotating backwards to free the frame to open until the hammer was at half cock position. Moving the hammer to this position also withdrew the firing pin into the frame.
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However most New Model Number Threes did have a rebounding hammer. In this photo I am forcing the hammer all the way forward with my thumb. This is the position the hammer would be in when it fired a cartridge.
But when I release the hammer, the trigger spring and the angle of the sear forces the hammer back slightly and the sear pops into a tiny recess in the hammer. In this position, the hammer cannot move forward. The firing pin has been pulled back into the frame, but the hammer is not back far enough for the slot in the hammer to clear the tab on the latch. The bolt has not yet been withdrawn, so the cylinder is still locked at battery and the gun cannot be broken open.
When the hammer is pulled back slightly to the 'half cock' position, the bolt withdraws to allow the cylinder to spin, and the hammer slot clears the shelf in the latch, allowing the revolver to be broken open.
This photo shows the details of the latch and hammer of the New Model Number Three. When the hammer slot clears the shelf on the latch, the latch can be rotated up to break open the revolver.
By the way the features of the parts that keep the New Model Number Three hammer back in the rebounded position are relatively fragile. Just as with a Colt, I would never keep a live round under the hammer in this gun. If it fell on the hammer, something would probably break and the gun would probably discharge.
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Good point and great pictures, but not all the S&W breaktops had either a rebounding hammer or that locking type hammer. The single actions didn't and only the late DA's had rebounding hammers; the First Model No. 3, didn't have either.
Actually, I am not sure the hammer locking into the top strap was to make sure the hammer was at half-cock before the gun could be opened; since it was provided only on the big bore revolvers, I think it more likely that its primary duty was to provide an additional latch to help keep the gun closed during firing.
In any case, most of the top-breaks by S&W and others did not have rebounding hammers; the camming action when the cylinder swung away from the standing breech was enough to push the firing pin and hammer back so it didn't prevent opening the gun. But with a swing cylinder, there is no force pushing the firing pin back and without a rebounding hammer (or frame mounted spring loaded firing pin) the cylinder can be hard to open. This can be tried by removing the rebound slide on an S&W and letting the hammer down with the firing pin in a fired primer, then trying to open the cylinder.
Jim
Actually, I am not sure the hammer locking into the top strap was to make sure the hammer was at half-cock before the gun could be opened; since it was provided only on the big bore revolvers, I think it more likely that its primary duty was to provide an additional latch to help keep the gun closed during firing.
In any case, most of the top-breaks by S&W and others did not have rebounding hammers; the camming action when the cylinder swung away from the standing breech was enough to push the firing pin and hammer back so it didn't prevent opening the gun. But with a swing cylinder, there is no force pushing the firing pin back and without a rebounding hammer (or frame mounted spring loaded firing pin) the cylinder can be hard to open. This can be tried by removing the rebound slide on an S&W and letting the hammer down with the firing pin in a fired primer, then trying to open the cylinder.
Jim
WELL........since we are talking break tops....The first handgun I ever fired was a S&W 32 caliber break top. Trigger pull was bad and the barrel only about 3" but you broke the top and all the cartridges popped out. I have often thought that reloading a break top has to be faster than a swing out cylinder and wonder why more effort wasn't made to create a better break top. Is the lock up too weak for powerful cartridges? 