Checking the B/C gap on S&W?

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Postman

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I just received my 686+ from Smith and Wesson's custom shop. I bought the gun a month ago and had it sent right back to the factory for their custom action job. The gap between the forcing cone and the cylinder was supposed to be reset, presumably to a tighter tolerence than before. Now that I have the gun home, the gap seems pretty large. I can see a good bit of light between the two, and it is certainly larger than the gap on my Ruger Blackhawk.
Does anyone know how big the gap should be, how I could check for myself, and if Smith and Wesson's custom shop has such a solid reputation that I should just trust their work? Thanks in advance.
 
Barrel to cylinder gap is checked with a feeler guage and should be between .003 and .006". Cylinder gap will enlarge with use, but coming from the factory it should not be larger than .007". Check it from both sides of the barrel in case the barrel face is uneven (tighter on one side than the other) in which case it will need truing. A smaller gap is not necessarily better as residue buildup from firing can begin to bind the cylinder. A clearance of .005" is considered ideal.
 
Any auto parts store will have them, along with places like Sears who deal in tools. They are a set of metal shims at different thickness. Your auto mech uses them to check on the spark plug gap in cars with plugs. Just be sure and get the one with mutiple shims and not the one that gets thicker as you go.
 
Thank you, now I know what to look for to judge the B/C gap. I'm still wondering, how does Smith & Wesson's custom shop rank?
 
Saw a pretty extensive test a while back, may have been in Guns & Ammo, of the effect of B/C on handgun performance.

They used a Dan Wesson revolver, in which the B/C can be adjusted.

In the final analysis, the B/C gap seemed to have zilch effect upon the guns ability to shoot straight. Exceptions: gap too tight, so that as the gun heated up, the cylinder would bind.

How does yours fire?

(The S&W Performance Center/Custom Shop apparently does pretty good work, but its not quite the same as having a top-quality gunsmith do the work. S&W does have top-quality gunsmiths working there, but the quality apparently varies from 'smith to 'smith [from good to outstanding]. A gun sent in get put into line, and you'll never know who's going to do the work. Its a "job" shop.)
 
If you are the old fashioned type who uses a blade razor, a double edge razor blade goes about .005.

The barrel-cylinder gap should be .005-.006. If it is any less, the problem is not fouling, but that the heat from firing expands both barrel and cylinder and after a few cylinders full the cylinder won't turn. This has been a problem in Cowboy Action Shooting with the SAA, S&W American/Schofield and their various clones.

Jim
 
Once again, thanks for all the info. I picked up a feeler gauge at Sears this morning and the gap is .006 exactly so I guess everything is cool.
 
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