I recently took delivery on a new 638 and noticed that the forcing cone on this gun is almost non existent compared to my K and N frames. There also seems to be a rough edge(burrs) around the cone. Is this normal with the new Smith J frames?

This article (http://www.hipowersandhandguns.com/S...omparisons.htm) has pictures of forcing cones from J, K, L & N frames. One thing I noticed is that the J-frame forcing cone is buried more in the frame, which might help performance. The K frame milled spot might create a weakness at the 6 o'clock position that is out of proportion to the thickness...I'm no expert in metallurgy, but believe symmetrical shapes have greater strength than asymmetrical.

Rough spots...saw a 627 Pro series with a big burr sticking out the end of the muzzle. When I pointed it out to the shop, they twisted it off and said, "Gone now!" I didn't buy there...

Where are the burrs on the cone?

The burrs are to the inside edge of the cone. The gun has not been fired yet, so I'm sure these aren't lead shavings.

My 642 does have a pretty "sharp" outer edge on the forcing cone. The face of the cone is rough also, but hasn't caused any particular problems. It caught my eye the first time cleaning as it was very rough/sharp. You would think for what these run they would at least take off the sharp edges.

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Enter through the narrow gate

Well, it seems that the burrs were indeed lead shavings. I suppose they were from the test firing. I would have thought the gun would have been cleaned after the testing and prior to packaging. Must be a sign of the times.
There is quite a sharp edge around the forcing cone of my 638 both inside and out, also, arrowhd. Seems like they could have chamfered both edges to remove that edge.
I'm going to keep a close eye on this situation and see if I get more lead shavings around the cone. If so, this gun may be making a trip back to S&W to have some work in that area.

I just put thirty rounds of Winchester white box target 125gr. FMJ's through the gun and there does not appear to be any shaving of the jacketed bullets on the forcing cone. I haven't opened the envelope that the spent test casing is in, but this makes me wonder what S&W uses for test ammo.

Just picked my 642 couple days ago and first link in google pointed to this thread I've noticed that forcing cone on mine has sharp rough edges I guess nothing has changed in almost 3 years. Has anyone tried to contact S&W about this issue ? Mine definitely not lead shaving (I've shoot about 100 plated rounds) and surface is so rough that q-tips catching on and leave tons of fibers behind

After a couple thousand rounds, the inside edge will smooth out. It is one of the signs of a well used gun, versus one that has not been shot much, when checking used revolvers. They are all sharp when new, and smooth out with lots of shooting. It is nothing to worry about, unless you get splatter to your face, or extreme lead build-up, both of which are signs of trouble, and not necessarily forcing cone trouble, but rather timing issues....