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“Normal” barrel-cylinder gap (BCG)?


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What would be considered “normal” for a modern revolver of quality manufacture?

 

I had the feeler gauges out looking at some Smith & Wessons this weekend.  Two recent J-frames came in at about .002” as well as a 1983 L-frame 686.  But then a tried a 1960s N-frame Highway Patrolman and it was at .009”.

 

They all shoot great so there’s not an issue there.  The two J-frames are going to get tested over a chronograph this weekend.  One had been magnaported.  One has the original barrel. Luckily their BCGs were near identical. 

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Howdy Charlie Harley;

One thing to keep in mind is that there are Fast barrels and slow barrels, so even if two barrels seem the same, same cylinder gap and all ...

Velocities might be quite different, pressures can also vary...

Have fun....

 

Jabez Cowboy 

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The dimensional tolerances depend on the manufacturer and the model. I would contact the manufacturer and ask. 
I had an S&W model 60 Pro that I was having issues with. I called S&W and asked about the B/C gap. They said the spec was .004”-.007” for that model. I asked if that was the spec for all their revolvers. They answered “No. It depends on the model.”

The gap on that gun was .005” on all chambers. It was in spec. 
 

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Charlie,

 

"NORMAL" is a setting on a Clothes Dryer.  The words "Normal" and "Gun" do not belong in the same sentence  B)

 

Beyond that, I always look for .002 - .005.  Depending on Make, Model, Manufacture, Age, Use, Etc., and whether or not ya hold yer tongue just right. 

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4 hours ago, Colorado Coffinmaker said:

and whether or not ya hold yer tongue just right. 

Very, very important! It helps to cock your jaw bit as well. :D

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From another website, his 28 had a cylinder gap of .014

"I called the repair center, and a very nice lady whose name I unfortunately cannot recall told me that that gun should have never made it out the door in that condition no matter when it was produced. She told me to ship it to them and they would fix it. I did so, and when it came back it had had the barrel set back, the forcing cone recut, and the gap set at .004 with NO cylinder play. A shootin' machine if ever there was one."

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Hmm, I'm going to look at the gap on the gun I am having misfires on. A 1940 or earlier 22lr. I'm looking at shimming the cylinder back to correct a misfire problem. I can see a lot of stuff spray out of the gap when it does go off.

 

As I understand the recommended grip for revolvers, there is a clear reason for crossing the thumbs:

 

 

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