Question on the old hammer block safety

[tipoc]

I have two different versions of the story where the Victory model fell onto the deck of a ship during WWII, discharged and led to the recall of 40,000 M&P Victory Model revolvers for retrofitting. The discrepancy involves the mechanics of the gun and what was wrong that led to the recall.

The first is from "History of Smith and Wesson" by Roy Jinks in 1977. It says, page 164...

"...The most important change was the incorporation of a new hammer block. The hammer block used on the .38 Military and Police during most of World War II...The return of the hammer block was dependent on spring action. Excessive dirt or heavy grease could prevent the hammer block from returning to the position of blocking the hammer, thus eliminating the secondary safety device to prevent accidental discharge of the revolver when dropped."

Jinks' early account lays the blame for the discharge on the gunked up spring.

Jinks then says that Hellstrom heard of it and S&W rushed to come up with a fix.

So that's one version.

The second is from the third edition of teh Standard Catalog pg. 142.
The gun drops on a deck...

"This prompted the Navy to investigate and request, through Springfield Armory, a better hammer block design. The former hammer safety was a shoulder on the rebound slide forced against a shoulder on the hammer. These "shoulders" kept the hammer nose off the cartridge in the down position. Enough force would shear the hammer pivot and the hammer nose would strike the primer, discharging the cartridge."

There is no doubt that the revolver dropped on the deck and the gun fired killing a sailor. This event led to a redesign.

My question is what was the initial problem, the gunked up spring or a broken "shoulder".

tipoc

 

[DWalt]

Pate's book provides a fairly thorough discussion, and Appendix F is devoted entirely to the subject. The information is too lengthy to discuss fully, but the conclusion was that the solution is "It was suggested that a hammer block having more metal between the hammer and the frame be used, and this block be supported at both sides of the hammer recess in the frame." In short, the old hammer block design was simply too weak to withstand a long drop if the gun landed on the hammer. It was found that a 2 pound weight falling 2-1/2' onto the hammer was enough to cause an accidental discharge with the old-style revolvers. Extensive tests were performed by dropping various weights from various heights on the hammer, and are described in some detail. Best to read the appendix if you can find it, if you are really interested. It's about 12 pages long, much of which consists of various Army reports and letters.

 

[tipoc]

Thanks. I just dug out my copy of Pate's "U.S. Handguns of World War II: The secondary pistols and revolvers". I'll read through this.

tipoc

 

[Skeetr57]

There were two types of hammer block safeties in S&W M&P revolvers built after the hammer block was patented in 1914.The first one was actuated by a pin that rode against the back side of the hand to retract the hammer block into the side plate, and also provided the spring tension to the hand. The second type, adopted in the mid twenties, also worked from the hand, but the hand had a ramp on its rear side that rode against a "flag" on the hammer block to force it back into the side plate as the trigger was pulled. All S&W hand ejectors after about 1906 had the hump on the rebound slide and the foot of the hammer that also acted as a hammer block. Both the first and second types of hammer block depended on the spring action of the hammer block to extend the block into the path of the hammer, so either rust or congealed grease could prevent proper operation, but the rebound slide/hammer interface would also have to fail to have an accidental discharge. The hammer block that was developed late in WWII is the same one used today on S&W revolvers.

 

[Sodacracker]

Very interesting - and just what I was looking for! I appreciate the help.

 

[Absalom]

.... and led to the recall of 40,000 M&P Victory Model revolvers for retrofitting.

Just because I enjoy picking nits:

This was not a recall in any modern sense of the word.

The factory designed the fix and began shipping the “new improved” design to the military starting in mid-January 1945. And in May 1945, a Navy refurbishing contract for 40,000 guns included retrofitting those guns with the new hammer block.

However, S&W appears to have felt no urge to let other recipients enjoy the benefit of the new safety. As late as June 1945, earlier-produced Victorys shipped to DSC recipients without the new safety. I have one like that shipped 6/6/45.

 

[Hondo44]

Pate's book provides a fairly thorough discussion, and Appendix F is devoted entirely to the subject. The information is too lengthy to discuss fully, but the conclusion was that the solution is "It was suggested that a hammer block having more metal between the hammer and the frame be used, and this block be supported at both sides of the hammer recess in the frame." In short, the old hammer block design was simply too weak to withstand a long drop if the gun landed on the hammer. It was found that a 2 pound weight falling 2-1/2' onto the hammer was enough to cause an accidental discharge with the old-style revolvers. Extensive tests were performed by dropping various weights from various heights on the hammer, and are described in some detail. Best to read the appendix if you can find it, if you are really interested. It's about 12 pages long, much of which consists of various Army reports and letters.

Was Pate's discussion dealing specifically with the "Navy death" incident?

It sounds more like it addresses the 1st hammer block involving the hammer foot and rebound slide. That safety block also provided no protection if the gun was dropped and sheared the hammer pivot pin.

The problem with the two side plate mounted, hand activated hammer blocks is that they are only positive in one direction, and that is when the hammer block is mechanically moved out of the way of the hammer by the hand. But for them to return to a blocking position, they are only moved by the springs behind them (the earlier one a coil spring and the latter one a flat spring). Thus, if cosmoline, rust or gunk was restricting them, they would not return to the blocking position in front of the hammer. Which is my understanding of the case in the Navy incident. Thus when either of these two hammer blocks worked correctly, they also work if the hammer pivot pin is sheared off.