Hi,

I have an M&P 340 j-frame and noticed the other day that the cylinder moves forward and rearward about 1/16" when it's unlocked. It feels pretty loose and I'm pretty sure it hasn't always done this. I have about 1000 rounds through the pistol. The extractor rod moves along with they clinder when I jiggle it forward and backward.

When the cylinder locks up I can still shake it ever so slightly but it is a lot less than when it's unlocked.

Should this gun be looked at for repair or is this normal?

This is completely normal and there is nothing to worry about.

When the cylinder is open it can move around a bit, which will have no bearing on the performance or safety of the revolver. The only time that "endshake" matter is when the cylinder is in the firing position.

Just to clarify things a bit, let's assume that by "unlocked" you mean the cylinder is open for loading. With the cylinder in this position the only thing that stops the cylinder from being lifted completely off the crane is a small stop either formed or pressed into the frame at the lower rear of the frame window. Because this stop is only there to prevent the cylinder from coming off the crane if you tip the barrel up to clear the cylinder, it's not tightly fitted to the cylinder. Because of this, the movement that you are observing is completely normal.

Now, if your seeing this much movement when the cylinder is closed, then you have a problem that needs to be corrected by a gunsmith. With the cylinder closed, any fore and aft movement of the cylinder is referred to as End Shake and the normal range for this movement is 0.001 to 0.002 inch. If you're seeing 1/16 inch of fore and aft movement with the cylinder closed, you want to cease using the gun immediately and either contact S&W or take it to a S&W armorer.

Right, by unlocked I meant cylinder open for loading. That is the only position in which the movement occurs. There is not really any significant movement when the cylinder is closed, maybe a very small amount but hardly any.

The only reason i asked the question is that the pistol has not always done this....in fact I went to close the cylinder once at the range and the cylinder was protruding too far rearward and would not close, I had to give it a little tap forward to get it to close. I was using a speedloader and was afraid I might have damaged the pistol.

It sounds like the gun just working itself in, loosening up. It seems within tolerance though.

__________________
Fast is fine;accurate is final

My 340PD has the same movement. The rearward movement is just enough that the edge of the cylinder rubbed off a tiny slice of the bluing on the left side of the frame (the side to which the cylinder opens) just below cylinder cutout. My stainless 640 also has the same movement, but, naturally, without the loss of color.

I just got a warranty replacement 340PD due to a cracked frame.

After 5 rounds of 357, while ejecting the spent casings, I noticed that the the cylinder moved past the stop on the frame. It looks as though the stop on the frame does not protrude enough or the cylinder is swinging too far away from the frame.

When the gun is reloaded and the cylinder is closed everything works OK.

Is there something I can do to tighten this up or should I send it back to S&W? This is my favorite carry gun and I hate to not have it.

Sorry, it needs to go back to S&W.

If the cylinder can override the cylinder stop, either the cylinder will bind badly, or can even literally fall off the gun.

On the older S&W's you could install a higher cylinder stop, but in the newer guns with the long stop machined as part of the frame, it's a factory repair-only.

I feel your pain. I sent one back about a month ago for the same problem. Must be pretty common. I dont know why they dont make the protrusion on the frame stick out more?