Smith wheel gun expert - Chime in!

**Mity2** · August 21st, 2010, 12:02 PM

I have Model 65, and 686.

I recently measure the cylinder gap on both of them, and my 686 showed 0.254mm(or 0.010") while cylinder is pulled back , and o.102mm(or 0.004") with cylinder pushed forword.

My understanding is that you subtract smaller number(cylinder pushed forword) from bigger number(Cylinder pulled backword):

0.254mm-0.102mm=0.152mm (or 0.010"-0.004"=0.006")

So my cylinder gap of my 686 is 0.152mm or 0.006"

And my M65 was 0.279mm(0.011") cylinder pulled back, and showed whoping(0.038mm(0.0015").
So that comes to:

0.279mm-0.038mm=0.241mm (or 0.011"-0.0015"=0.0095")

Is my number sound right to you guys?

**DavidTM** · August 21st, 2010, 12:23 PM

This info is from http://www.cactustactical.com/reload...tion-guide.doc -

Barrel-to-cylinder gap: The ideal B/C gap is .006”. A close gap will cause the cylinder to drag when fouled from shooting residue. A wide gap will loose muzzle velocity and may spit particles. The normal usable range is from .004~.010”

Hold the cylinder to the rear and insert the thickest gap gauge that will fit between the cylinder face and the rear of the barrel (with friction). This will be the B/C gap.

So,,,,...IMHO...If your not getting any "spitting" of lead or copper out of the side of the cylinder when you shoot (and I've had this.....it stings like hell) then your gap, according to this article, seems to be within "spec's".

Dave

**Steve_NEPhila** · August 21st, 2010, 12:57 PM

You really should spend more time shooting then measuring...

Do not worry about your b/c gap unless you are having obvious problems. As long as it hits where you want it to, does not hurt to shoot and is not rattling itself apart, rock on.

**Dave_n** · August 21st, 2010, 04:05 PM

Rather than front to back movement (which is easily fixable with shims) your real problem occurs if you have any movement when the hammer is cocked and you try to move the cylinder, or when the hammer is in the fired position with the trigger held back. That means that the hand is not functioning or the cylinder stop is not catching, or both. Valid for every revolver except Webley as they only lock on firing, so must always test a Webley for rotational movement with the trigger back. Dave_n

**Rundownfid** · August 22nd, 2010, 06:43 PM

What you are measuring with your cylinder pushed forward and pulled backward is end shake. Cylinder gap is measured by inserting a feeler gauge between the forcing cone and the cylinder (actually you should measure all for chambers as they are not necessarily the same. I also believe .006 is about ideal, but .004 to .010 is considered OK, as I recall.