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DWF Supporters
September 20, 2020
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So I've got a pile of Dan's now. My CZ/Norwich 715 came with a 0.006" feeler gauge and my Monson 7445 came with a 0.006" feeler gauge in the box. My 40 357 Max did not come with box or anything, I bought it just the gun alone. I read somewhere that the model 40 should have a 0.002" cylinder gap. Can anyone verify this for me? My Ruger 357 Maximum has around 0.003". What about my 7445....is the 0.006" gauge that came in the box the correct gauge for that gun?
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Dans Club
March 25, 2013
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.002 for the model 40 is correct. I would think it would be good for the 445. The reason the 715 is .006 is that the small frame cylinder will expand after a couple of cylinders worth of rounds and bind. I prefer .003 or4 for the small frame. Also the cylinder face gets carboned up and may cause it to bind. If you use a smaller gap then wipe the cylinder face after a couple of reloads. Always take the barrel tool with you when shooting. Also, the small frame cylinders were not always even. Some chambers could be prouder than others. . 006 ensured it would not bind if that was the case.
Instead of using the factory shim get a set of shims from the auto parts store. Find the one for your gun. They are very inexpensive. I hold the gun up to the light and eyeball the gape. Doesn't take long to learn what works. If it binds reset it.
DWF Supporters
September 20, 2020
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Thanks Ole Dog! Huge help!
October 17, 2017
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There are many opinions on this subject although .004 - .006 has generally been the industry standard for many decades regardless of caliber. To my knowledge there has never been any documented proof that a smaller or larger gap has any effect on accuracy, and only the smallest effect on velocity has ever been noted. Given a very tight gap (less than .002) the revolver will often exhibit cylinder binding especially if lead bullets are used. Given a very wide gap (more than .012) the shooter may experience some spitting of particles out of the gap, again, especially if lead bullets are used at higher velocities. We DW owners have the unique ability to control C/B gap every time we change out a barrel, but I don't feel the need to stray much from the industry standard.
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