I have a 327pc that has this odd mark on the bottom of the frame window.


I was shooting it with some lead rounds then followed with a copper round and noticed the copper round did not hit the forcing cone on center.

I was kinda puzzled. Then thought the center pin is floating during recoil letting the cylinder unlock when firing. So I colored the frame with a marker and fired a 357 round in it. The marker was transferred to the cylinder.


I contacted s&w and they wanted to look at it. The 327pc came back with a new cylinder and crane. So I conducted the same test.



I don't think it's unlocking with 38sp but I think it's still unlocking with 357 mag. It's too hard to tell. I'm not going to shoot many more 357 mags in it. I have heard of cylinder float but not center pin float.

I think it would be a good idea to a close eye on the s&w revolvers that don't have a front lock on the barrel.

Nice sleuth work. That is crazy!

The recoil impulse could be "sharp" enough in a lightweight gun that the mass of the thumbpiece stays stationary as the gun recoils rearward, unlocking the cylinder. Joe

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Wisdom chases me; I'm faster

Nice theory, but untrue! All N-Frame revolvers after the -2E (Endurance Package) have one or both of 1) A short pin on the hand that rises between the frame and bolt specifically to keep this from happening, and 2) A "Bolt Lock" articulated to the trigger that also physically locks the bolt to the rear while the trigger is pulled! It is remotely possible that the inertia of the center pin could cause unlocking, but quite unlikely.

The odd thing about OPs revolver is that if the cylinder is striking the frame I would expect to see marks all around the cylinder matching the mark on the bottom of the cylinder window. There doesn't appear to be one!

You are relaxing your trigger finger when the guns goes bang! Then, under the recoil, you are slapping the trigger which is enough to unlock the cylinder! Very little movement of the trigger is required to unlatch the cylinder. I do the same thing EVERY TIME I fire a 500. Pull thru and hold the trigger back!
jcelect

Had a Model 58 some time back that would unlock enough that the cylinder would swing open every once in a while. Did it twice during an IDPA match in which I was shooting factory 210 gr JSP loads. (Just for giggles, but still did tolerably well.) Not a problem with the WW 175gr Silvertips, so that's what I used thereafter.

IMO you should be contacting S&W about having them look at your revolver under warranty. Because I just can't conceive of how there could be enough flex in a properly fitted yoke to allow the cylinder to contact the frame like that. Now, I'll grant that all my S&W revolvers are Stainless Steel but I have NEVER EVER seen anything like this happen with mine and I've loaded up some distinctly warm 357 Magnums.

Center pin float is the only explanation I can think of. I have been told titanium is very hard. That maybe why the softer alloy frame doesn't leave a mark on the cylinder.

I don't believe I'm relaxing my trigger finger under recoil. When I first noticed the off center hits in the forcing cone I had been shooting 148gr dewc 38sp target loads. Not a heavy recoiling load.

How's the accuracy? I would think hitting the forcing cone off center would cause problems.

Nice work figuring that out. If you can confirm it's still hitting the frame I would send it back again. Eventually they should fix the problem or replace the gun.

I would think the problem would be happening to some extent with 38's. Just not to the same level as firing 357's.

Would a heavier (longer) center pin spring help keep the pin in "battery" during recoil?

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Ret. LE, FA Instr, S&W Armorer

Accuracy was pretty good but spit lead and could not keep the barrel tight.

I don't know of a extra power center pin spring. I asked Wolfe springs and they don't make any.

Don't worry about it. Send it in. There is something wrong there that the factory needs to see and correct.

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44 Garrett Defender Ammo 4 me.

I thought I had updated this thread but have not. S&W wanted the 327 return. They replaced the cylinder. The 327 still has center pin float and the cylinder still hits the frame as before. Also the barrel still won't stay tight.

I believe I have a solution to the center pin float. I disassembled the cylinder and tapped the end of the ejector for a 6-32 screw.

The only spring I had that fit inside the ejector was a browning hi power mag disconnect spring. So I cut the spring in half. Here's a picture of the parts before assembly and shortening of the center pin.

Here's a couple of pictures after assembly.


Now that the center pin is supported it should not be floating any more. I will test it when I get a chance.

Unbelievable . . .

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Wisdom comes thru fear . . .

Wow! Talk about your voided warranty - no offense intended, but if you were having a problem that made you think you needed this, your revolver should have gone back to S&W for warranty service. i sure hope you remembered to use a screw with a left-handed thread....

I have no expectations of a warranty in a used gun. I have sent this 327 back to s&w and when it was returned it continued to have the same problem. I could keep complaining to s&w till they tell me it is in spec and they no longer need to see it. Then my options are sell it so it can be somebody else's problem, don't shoot it, shoot it till it breaks or find a fix. Since I don't have the same confidence in a unsupported center pin as s&w does and I like the 327 and want to use it safely I looked for a fix. S&w is making a lot of revolvers with unsupported center pins and if they are heavy recoiling I think center pin float is a serious concern much like cylinder floating had to be addressed in the heavy recoiling m29.

These new guns with the ball detent don't have a center pin spring? How do they secure the rear of the cylinder? That was a proven design element for 100 years. I understand the locking bolt for the tip of the ejector rod is gone, but without a center pin spring how are they suppose to secure the rear of the cylinder?

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~ S&W aficionado in training ~

There is a center pin spring but not a front lock with a front spring to support the center pin. In a heavy fast recoiling revolver the center pin floats or stays in place as the revolver recoils away from the center pin. These revolvers can pull bullets from their cases and in the same way pull the center pin out of lock.

In the tradition design the center pin spring pushed the center pin back into the recoil shield. I help secure the rear of the cylinder. It didn't affect the extractor rod in any way.

The extractor rod was pushed forward by the extractor spring. It helped to lock the front of the rod to the locking bolt (which was also spring loaded). This was suppose to secure the front of the cylinder.

All I see this mod doing is pushing the center pin back into the recoil shield. Which is what the old style center pin spring always did.

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~ S&W aficionado in training ~

Good one on Ya ! Don't you just love it when someone takes the iniative to brainstorm an idea that works around a problem befuddling the EXPERTS. Just love it. Right up Elmer's alley. I say, Good one on Ya mate!

I got a break today and test fired this 327. I marked the frame with a sharpie as before and fired some 357 mags in it. Here's the before photos.




And the after photos.




The center pin is no longer floating and the cylinder is not hitting the frame. Also the barrel has stayed tight after 22 rounds. It doesn't sound like a lot but for this problem child it is an accomplishment.