My problem with the Yoke-screw design

[American1776]

*This is not a S&W bashing or rant*. I like S&W's, and my favorite 9mm is my model 539.

I recently noticed a perceived 'weakness' in the design of the newer S&W revolvers: the yoke retaining screw.

The old Yoke retaining screws were solid, and were fitted to the yoke. This made a quite solid yoke, which could be relied on to stay secure and not slip out of the frame.

The new Yoke screw has a spring loaded plunger that mates with the yoke detent. This causes the yoke to actually wiggle in and out of the frame when you apply any meaningful pressure forward on the cylinder while reloading.

This plunger that retains the yoke can be defeated with just pressure on the cylinder, which could cause the entire yoke and cylinder to fall free from the frame during a reload. This is not something you want in a defensive firearm.

Can anybody comment on this perceived weakness is the design? I've been wanting a scandium J-frame for carry, but I cannot get myself to accept this *insecure* yoke.

[S&WIowegan]

You are quite correct about the potential problem associated with the spring-loaded plunger arrangement in the yoke screw. This innovation goes back over 25 years since the production of 625-2 models. I had trouble extracting my empty brass and managed to remove the entire cylinder/yoke assembly. I have personally seen it happen to others during a match.

I suspect that the spring-loaded yoke screw reduces assembly time and saves money. My suggestion is to add a bit of Lock-tite to the yoke screw to help keep it tight. This is tricky because too much Lock-tite will freeze up the yoke.

[American1776]

Thanks for your thoughts S&WIowegan. I greatly respect your most expert opinion.

I wonder if it would be possible to get the correct screw for the yoke, and then actually cut it down to the requisite length, and then file it by hand to actually fit it properly to the yoke?

It sure beats my current options: 1) buy only Rugers, or 2) buy a new S&W and constantly worry about the cylinder falling out of the frame.

[michpatriot]

How about a small pin inserted inside of the spring, fitted to the right length, preventing the plunger tip from fully depressing?

[S&WIowegan]

Originally Posted by American1776

Thanks for your thoughts S&WIowegan. I greatly respect your most expert opinion.

I wonder if it would be possible to get the correct screw for the yoke, and then actually cut it down to the requisite length, and then file it by hand to actually fit it properly to the yoke?

It sure beats my current options: 1) buy only Rugers, or 2) buy a new S&W and constantly worry about the cylinder falling out of the frame.

You can indeed buy new yoke screws from Brownells. I keep a supply of blue, nickel and stainless yoke screws. The problem isn't quite as extreme as you imagine. I've only seen it happen in competition when extreme force is applied to the yoke/cylinder assembly during speed reloads. Of course, you can keep the correct size screw driver in your shooting bag and tighten yoke screw before shooting.

[muddocktor]

Originally Posted by American1776

Thanks for your thoughts S&WIowegan. I greatly respect your most expert opinion.

I wonder if it would be possible to get the correct screw for the yoke, and then actually cut it down to the requisite length, and then file it by hand to actually fit it properly to the yoke?

It sure beats my current options: 1) buy only Rugers, or 2) buy a new S&W and constantly worry about the cylinder falling out of the frame.

I was just looking at my 627 Pro, I think it would be possible to file down the correct sized screw to fit the channel in the yoke. It would take quite a bit of filing and fitting, but it looks doable. You would have to profile the end to look like the pin on the new style yoke screw though since the cut is "V" shaped in the newer yokes.

Another idea you might try is to buy yourself another new style yoke screw and drop a drop of Loctite red into the space between the pin and the body and install it in your gun and let the Loctite dry. Just be sure to not get any of that on the threads of the yoke retention screw.

[Tyrod]

Somebody has a screw loose!

[torizus]

Originally Posted by Tyrod

Somebody has a screw loose!

And thas no yoke

[Steve912]

Originally Posted by torizus

And thas no yoke

...don't egg him on, now!!

[H Richard]

American1776, I am in agreement with you. I recall when this change was made, and I am sure it was as much or more for elimination of skilled final fitting than improvement of product. I do however have several of these and have never had a problem with any of them, but I am no longer a competitive shooter loading under stress. I see no reason a gunsmith or skilled machinist couldn't relieve the yoke to fit the "older" screw and have an older style made to fit. An older replacement screw wouldn't work as the screw body of the new screws is larger.

[Hondo44]

It's not an issue of the yoke screw coming loose. The yoke can be pushed out even when the screw is tight.

H Richard is correct. The yoke screw w/plunger and spring is larger diam than the old screw and other side plate screws.

But one can just pull the plunger and spring and replace with a pressed in or locktited pin, fitted to the yoke shaft radial V groove.

[michpatriot]

Today I disassembled my 340 yoke assy., upon compressing the plunger into the screw I wondered if the yoke slot would indeed clear the plunger,I had my doubts. It became obvious while looking into the hole in the front of the frame that the plunger still intersects the yoke while fully compressed. I used a screwdriver down the hole where the yoke pivots inside and depressed the plunger all the way and there is no way the yoke is going to slide out at all, no chance.. notta! The design on my 340 will not allow removal of the yoke without removing the screw/plunger or breaking off the end of the yoke.

[Hondo44]

There may be something else afoot here. S&W may have an issue of some out of tolerance screws where the plunger retracts too far into the screw. A call to them might be a good idea.

[H Richard]

What Jim says, is there a "standard" for the pin length to extend from the body of the screw? That would be a good thing to know, and J,K & L may be different.

[muddocktor]

Originally Posted by H Richard

What Jim says, is there a "standard" for the pin length to extend from the body of the screw? That would be a good thing to know, and J,K & L may be different.

That was a good question, so I did a little sleuthing. I went to Numrich and checked out the new style yoke screws in N, L, K and J frame models and in all cases they show the same part number for them. So I would say that the yoke screw is the same for all frame sizes.

[twodog max]

Never had or seen a problem. Something else to not worry about.

[American1776]

Originally Posted by twodog max

Never had or seen a problem. Something else to not worry about.

A search on the forums will reveal some accounts of competitive shooters having their cylinder and yoke fall free from the frame during a reload. This is due to the plunger screw design.

A handgun that falls apart during a reload is something *I* would personally worry about. Your mileage on the issue may vary.

[michpatriot]

I wonder how much wear is a factor on the end of the yoke on the problem associated...heavily used competition revolvers being spoke of in this and other threads? Could the end of the plunger be worn and or the end of the yoke together make the perfect storm the average shooter will never see? The spring inside the plunger in its fully compressed state has all the coils touching, effectively halting any further shortening of the length of the screw assembly, if this spring were forgotten by a careless person during re assembly it would almost positively not securely retain the yoke. How many people know at least one person who works on guns that shouldn't? One or two instances of a severely worn/abused part, or a couple of instances of a forgotten spring behind a plunger by a novice gunsmith, amplified by the interweb... does not seem to be out of the realm of possibilities as it relates to this perceived sky is falling thread. I do not see any problem in my 340 yoke retention now or in the future after ACTUALLY looking into the hole where the yoke resides with the retention screw fully bottomed out, and the plunger fully compressed. I don't see any chance in my revolver of this ever happening.

[jaymoore]

Originally Posted by michpatriot

I wonder how much wear is a factor on the end of the yoke on the problem associated...heavily used competition revolvers being spoke of in this and other threads? Could the end of the plunger be worn and or the end of the yoke together make the perfect storm the average shooter will never see? The spring inside the plunger in its fully compressed state has all the coils touching, effectively halting any further shortening of the length of the screw assembly, if this spring were forgotten by a careless person during re assembly it would almost positively not securely retain the yoke....

It IS possible with some few revolvers. Seems an easy enough fix for a gunsmith or the aftermarket. A longer plunger that can be cut to such a length to preclude spontaneous disassembly, or a small stop pin located inside the spring (like the "trigger stop" pin inside the trigger return spring) would both fill the requirement.

Only mention it because I've seen it a very few times. USUALLY, you can't get the yoke to slide forward enough to have things come apart.

Don't believe it's a wear issue. Just tolerance stacking.

[Brendon]

Does that yoke screw plunger need to be oiled? Or does the tip need to be oiled and you squeeze it closed several times to get oil inside the spring area? I assume that spring area might want to start seizing up after a while? Or a non-issue?

I just got a brand new 625-8 and went ahead and ordered a bunch of extra side plate screws and yoke screws to keep as spares for the future encase they become obsolete or Smith changes the finish on them later. Also got spare strain screws as well.

Though there may be little risk of these becoming obsolete like the older parts since these are more mass produced style instead of the older parts.

[jaymoore]

Originally Posted by Brendon

Does that yoke screw plunger need to be oiled? Or does the tip need to be oiled and you squeeze it closed several times to get oil inside the spring area? I assume that spring area might want to start seizing up after a while? Or a non-issue?


....

I don't think a 1/4 drop of oil would hurt anything. My 940 has been submerged in lakes and creeks multiple times and nothing has yet to even look like it's corroding (or wearing for that matter.) The 340 M&P has proven to be a bit more sensitive, but the galvanic potential of the dissimilar metals is rather higher. (The aluminum alloy seems more susceptible than the steel alloy bits when exposed to the local waters.)

[twodog max]

Competition shooters are notorious for modifications and severe usage of the revolver. I have watched videos of these shooters and the speed and slam bang reloads they do are not what I would class as normal usage and fall almost into abuse category. Now I am not saying the demands of competition do not require such practices just that normal use does not produce the same wear and tear.
Nope I will not be worrying about this and actually have had problems in the past with the older screw design causing problems.
To each their own.

[S.B.]

I have never seen nor heard of this " perceived " problem ever happening? Can you document a few for me?
Steve

[L Pete]

This has been a known problem for those who use speedloaders. Apparently, the forceful use of a speed loader can push the yoke past the little detent used in the newer model yoke screws, causing the yoke to come out of the frame. It's known, and there have been a couple of fixes out there for competition revolvers. I'd hate for that to happen with a self defense revolver at a bad time. But Smith & Wesson lets the problem persist........

[S.B.]

Well, please give me someplace to begin looking for something on this?
Steve

[cmj8591]

I think if you are pushing the yoke out of the frame with your speed loader, you need a different reload technique. I can say that in years of range time, I've never seen this failure. This is a solution in search of a problem.

[jaymoore]

Originally Posted by twodog max

.... just that normal use does not produce the same wear and tear.
Nope I will not be worrying about this and actually have had problems in the past with the older screw design causing problems....

Now that IS a problem with which I've dealt multiple times. The old design screw often wears the rear of the yoke groove to the point that the cylinder front can crash the left rear side of the barrel at closing. Especially common with stainless revolvers. I've both welded and peened the yoke to repair. The P&R 629s seem especially prone. Just from normal use.

[S.B.]

Originally Posted by jaymoore

Now that IS a problem with which I've dealt multiple times. The old design screw often wears the rear of the yoke groove to the point that the cylinder front can crash the left rear side of the barrel at closing. Especially common with stainless revolvers. I've both welded and peened the yoke to repair. The P&R 629s seem especially prone. Just from normal use.

Wow, now that's endshake!!! And, accuracy didn't suffer?
Steve

[jaymoore]

Originally Posted by S.B.

Wow, now that's endshake!!! And, accuracy didn't suffer?
Steve

No. Actually, the endshake whilst closed would only be a few thousandths more than usual as the cylinder's forward travel is stopped by the end of the barrel. Can present as a binding drama, though, no surprise.

ETA: I reckon more than one has had the underlying cause of "excess endshake" been misdiagnosed as trouble on the upper portion of the yoke. Not hard to mask with endshake shims or yoke stretching except for that pesky crash when closing the cylinder. Easiest to note by removing the cylinder assembly and then just installing the yoke and screw in the frame. Check then for fore and aft movement of the yoke. In this case, less is best, up until the yoke actually binds whilst pivoting. (Seems this was a hand fit area in the old days and some definitely were done better than others! I have several spare old K frame yokes that show varying degrees of fitting skill....

One sign of lower yoke wear is wear on outer front edge of the cylinder and usually it's face. I may have some examples to photograph about somewhere.

[S.B.]

OK jaymoore, have it your way.
Steve

[jaymoore]

Originally Posted by S.B.

OK jaymoore, have it your way.
Steve

????

That would be a rarity!