76/760 Stock Wobble

[Jim in Texas]

I have read a number of postings complaining about excessive play in the 76/760 factory stock.  I have not personally encountered that problem, but I see how it could happen if the upper stock plate dimensions are not tightly controlled.  

I am attaching two photos illustrating what I believe are the relevant dimensions if you want to avoid excessive play in the stock.  These thoughts are based solely on observations of a limited number of guns by a hobbyist, not an expert.

First, the width of the slot for the folding stock should be a snug fit with the width of the folding portion of the stock – less than 0.002” wider than the corresponding portion of the stock.  In other words, you should not be able to slide a 0.002” feeler gauge between the stock and the slot in the top stock plate at the point shown by the blue arrow in the first photo.

Second, the depth of the slot in the upper stock plate needs to be deeper than the thickness of the corresponding portion of the stock.  Note the difference in height indicated by the two red arrows in the second photo.  Additionally, that wall of that portion of the upper stock plate needs to have a crisp 90-degree corner so there is nothing to help cam the stock out of its locked position.  

How do your own experiences compare?  If your stock has excessive play, how thick a feeler gauge can you slip between the stock and the outer wall of that slot?  Is that outer wall taller than the stock and does it have a crisp 90-degree corner?

If your upper stock plate has more generous clearances, you may be able to experiment by supergluing a thin shim onto the outer wall of the slot for the folding stock to see if that reduces the wobble.  If you later want to remove the shim, a short soak in acetone should weaken the superglue bond and allow you to pop it off without scratching the upper stock plate.  

If you like the results of your experiment, the upper stock plate looks like a relatively simple part to machine - simply adjust the dimensions to more closely match your stock.  If the stocks themselves have reasonably consistent dimensions, maybe someone like NavGunner or Brian could be enticed into making a run of tighter-fitting plates.

At any rate, these are my initial thoughts on the subject.  What are yours?  

[Rekraps]

Hey Jim, once again a very well thought out post.  I have two 76’s and in both cases the OEM stocks folded and snapped into position well.  The problem I has, as many others do also, is that any pressure at all on the hinge area and the stock folds.  This is not good at all when shooting.  Unlike the K which truly locks into place, the 76 just sits there, waiting to fold. 
 

This is why I purchased Brian Miles’ stock adapter.  It’s a perfect , non-permanent solution that is very strong and robust.  Plus it allows you to mount any aftermarket folding stock on the gun.  I elected to use the SIG Minimalist and it works great.  

[Jim in Texas]

Thanks for the feedback.  It is interesting that the self-folding issue seems more common with the S&W guns.  My Irvine stock is rigid in the open position and will not fold unless you first intentionally lift the top rail of the stock up and over the sidewall of the upper stock plate.  This suggests to me that the S&W guns are slightly different in this area.  Perhaps they have a slight bevel to the upper stock rail or the sidewall of the upper stock plate.  Alternatively, they may have enough play between the stock and upper stock plate to let the stock get a “running start” at trying to fold on its own. 

At the risk of being branded a heretic, I have noticed what appear to be several product improvements that were incorporated into the standardized Irvine guns with the stamped magazine housing.  Perhaps the tighter tolerance upper stock plate can be added to that list.  

At any rate, a new upper stock plate with these tighter tolerances should be relatively easy to make, and could be both installed and removed without any alterations to the gun itself.  If I wanted to keep the original appearance while also having a stock that does not want to fold all on its own, I would install the new upper stock plate for shooting and keep the original in a safe place for collector purposes.  This is analogous to replacing the internals on a Colt Thompson with USGI parts for shooting, while keeping the original Colt parts safe for posterity.

[AGLS]

I am a new board member, but I have been either a NFA dealer or a Class 8 importer for over 40 years. I have had over 10 Smith & Wesson M76's go through my licenses. The issue of the wobbly and accidentally folding stocks has plagued those guns from the beginning, and made re-sales difficult. A lot of people thought that it was a safety issue if the stock possibly folded while firing. Once, I had a machinist in Houston make me several stock plate sets that cured the problem. I know that he cut the mating edges with an opposite small angle that locked securely with each other until you were ready to fold the stock.  Unfortunately, the machinist retired many years ago. The 76's were very cheap back in those early days. I think that I was buying them for under $1,000, so it was hard to put any money on them. I also had a couple of police guns that arrived with broken front sight blades, where somebody took pliers to adjust the front sight. Since the barrels do not index into the receiver, it was very hard to sight in some of the guns.

[Remo Williams 1]

I use to collect as many machine gun related vhs tapes back in the late 80’s, early 90’s. The 76 was one of my most anticipated purchases. The gun shot great, except hollow points, but had excessive stock wobble. I found a police instructional video from a former Navy Seal who was a trainer in the Pennsylvania area. The video was on the 76, MP5 and MAC10. They taught slapping the closed stock of the 76 with the left hand to deploy the stock in immediate action drills. It made me cringe thinking this is making the problem worse. I wish I could remember the name of the tape.

[AGLS]

I remember in the late 1970's taking in trade five S&W model 76 from a small police department outside Houston, TX. A previous police chief had bought them thinking that they would be useful if they had race riots. The new police chief found out about the guns, and immediately wanted to dispose of them. I think that I gave the police department a $300 credit for each gun including the 30+ magazines, against the riot shotguns they wanted. The guns were in fairly good shape, except that they had not been stored properly, and the finish had some issues, plus the typical loose stocks. It took me three years to get rid of them. Nobody wanted them. I was finally able to sell them for a small profit to ranchers in west Texas who used to control javelina and coyotes, and kept them in the floorboards of their trucks during daily operations. I saw some of those guns years later when I was invited to a javelina shoot. The guns looked really ROUGH.

[Rekraps]

I wonder if anyone knows how many of the OEM M76's were lost in the twin towers collapse? I had heard that the NYPD stored several thousands of them there....

[Jim in Texas]

Rekraps -

The only printed information I recall seeing on that subject was a page in Frank Iannamico’s book where he lists the Model 76 guns originally purchased by the New York prison system.  I think there were about 107 guns on his list.  He goes on to say that 4 of them from Attica were being stored in a law office at the World Trade Center as evidence in a litigation case and were destroyed in the September 11 attack.