686 Cylinder Leading

[detox]

Just before forcing cone there is a sharp edge that collects lead when shooting cast bullets. What can be done to prevent this lead build up ?

Using my bore scope i examined the cylinders of my 686 against my Blackhawk. The 686 has a sharp edge before forcing cone with a gap of about .020" between case mouth and chambers sharp edge. Maybe this sharp edge is shaving lead? The Blackhawk has no sharp edge with smoother transition. I never noticed leading in this area of Blackhawk cylinder.

Here is diagram i tried to draw. Maybe our 686 guns need to be sent back to S&W to be modified to shoot cast.

[bhn22]

There's often a wire edge in that area from machining. I saw an article by Ed Harris about lapping that area in a .45 chamber, using an old 30-06 case as a lap. He used valve lapping compound. I don't know if a .223 case would work for a 357 or not. If nothing else, you may be able to cast yourself a lap. I'd only use compound where it's needed, and perhaps put simple grease on the areas I didn't want altered.

[detox]

Good idea. I may try lapping forcing cone later.

My Brass is thicker than the raised edge so maybe bullet is not being shaved. Unless alloy is too soft causing bullet to swell when fired. Next I plan on using linotype alloy or water quenching bullets to make them harder to prevent bullet deformation.

[reed1911]

Get a cutter and re-cut the forcing cone, a 60 degree is common.

[detox]

Looking thru Hawkeye borescope each cylinder throat aligns perfectly to barrel, but cylinder chambers appear to be cut off center to cylinder's throat like in picture. It may be not be enough to make a big difference?

[detox]

Hawkeye bore scope is a verygood tool to use while inspecting and before buying a new pistol or rifle.

BTW When i log on to Smith & Wesson sight a virus warning appears.

IT DOES NOT GET ANY BETTER THAN THIS!

[bhn22]

Your chambers could be cut crooked. Look at the primers in your fired cases, are the firing pin dents in the center of the primer?

[77ruger]

Have you discussed this with Smith & Wesson?
They will probable send you a prepaid shipper to send gun back and have it fixed.
My2cents.

[detox]

I think i am being a little too critical. The pictures above are a little exaggerated just for your better understanding of what i am talking about. Cylinder charge holes are not dead on perfect, but i think they may be close enough.

[Ben_51004]

Many gunsmiths that work on revolvers have the tools to check the diameter and angle of the forcing cone, and re-cut it if necessary, as well as chamfer the edge of the cut to eliminate the "sharp edge" that you noticed. Interestingly, I just did this work on a 686 in for repair. It's an easy fix if you can find someone with the right tools that's local. Probably not cost effective to buy the tools and do it yourself. Sending it back to S&W is another good alternative. Good luck.