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Old 10-11-2018, 07:45 AM
Hapworth Hapworth is online now
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The poster from castboolit's approach to measuring barrel-to-cylinder gap is interesting -- somewhat different from what S&W and Kuhnhausen, and has a few odd details.

Empty brass in the revolver for checking carry-up? Yes. For gap? New to me.

Running the action with the feeler in place doesn't allow a free hand to hold the cylinder rearward while measuring -- an integral part of the process.

The before and after proofing, and customer service numbers seem about right; .006" is generally considered the ideal balance between performance and reliability.

Never heard the notion that a .012" gap will stick a bullet in the barrel, and has never personally been experienced shooting that gap and larger.

S&W and Kuhnhausen recommend correcting end shake once it approaches .006".

Never heard of a "long cylinder" approach to correcting gap, though it's interesting and I can see how it might work. S&W pulls the barrel, turns the shoulder back a revolution and refits.

Simply, to measure b-c gap, hold the cylinder rearward and the largest feeler gauge you can comfortably pass between the barrel and cylinder faces is the gap for that charge hole; repeat for each, as sometimes the cylinder face isn't perfectly true (and often the barrel face isn't).

And measuring endshake, the cylinder must be held rearward on the first measurement, but also held forward on the second.

The specs on both your 686s are fine, with the older one slightly preferred.

What really matters is how they shoot...
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