Most people behind the gunshop counter today are ignorant of revolver mechanics. They just want to sell you the junk they have.
LEARN how to perform a "light technical inspection" or LTI to identify problems which are expensive fixes that make a used gun a "non-starter".
The Basics:
Open the cylinder, keeping the muzzle pointed in a safe direction.
Confirm that all cylinder charge holes are empty and that the bore is clear.
Confirm proper function of the thumbpiece when releasing and opening the cylinder.
S&Ws push forward, Colts pull backward, Ruger pushes inward.
Open and close the cylinder on each chamber, to ensure that the ejector rod is not sticky on any of chamber, due to burring of the tip of the ejector rod and subsequent drag on the forward locking bolt.
With the cylinder open, spin the cylinder and watch the end of the ejector rod for wobble.
Check with the fingers that the ejector rod is tight and not loose on threads. The threads in S&W ejector rods are fairly coarse, so taking the cylinder apart and amateur reasesmbly almost always requires some re-adjustment.
Verify that the ejector rod functions correctly at its full stroke and returns positively.
Inspect the small extractor alignment pins pressed into the cylinder, to ensure they’re not bent/broken/missing and that they properly engage their holes in the extractor.
Visually inspect locking bolt notches of cylinder for peening. If damaged DON"T buy the gun!
Press on the center pin which protrudes at the center of the extractor of an S&W or Ruger at rear of cylinder, to verify free center pin movement and positive return. Visually inspect the front end of the S&W center pin for peening.
Close the cylinder, grasping it with thumb and forefinger. The cylinder must not strike the barrel when closed! This may be caused by the yoke/crane screw being damaged, worn, loose, or from the gun having been shot loose by firing too many +P or +P+ loads, which produces excessive cylinder end shake, or in a gun being mis-assembled with a cylinder/yoke assembly from another gun [common in ex-foreign police imports now been seen on the surplus market].
Confirm that both front and rear of the center pin on S&W or older Ruger Six series lock positively fore & aft as the cylinder is closed. Inspect crane lock function lock on later Ruger DAs.
Visually inspect fit of yoke/ crane at front of frame for gaps, which indicates misalignment.
Visually inspect the barrel forcing cone for cracks! Especially check 6:00 region, where a barrel flat was milled on S&W to clear the cylinder gas ring, which commonly occurs after about 3000 full-charge .357 rounds. Anything strange here DON'T buy the gun!
Inspect the firing pin hole in the recoil plate/frame bushing for peening or burrs. On light alloy frames a ring peening of case rim diameter around the firing pin bushing is indicative of the revolver having been fired with more than a few +P loads, and is a clue to check end shake, etc. and correct as necessary.
If the yoke/crane doesn’t pivot freely, in opening and closure, inspect the race for the yoke/crane screw for galling or rub marks, indicating the screw is a trifle long and should carefully shortened before installing and tightening again. An easy fix usually, but use it to haggle the price. Often this occurs when side plate screws are shuffled around and the correct yoke screw doesn’t get into the forward hole, and one of the side plate screws gets inserted instead. Corrected in many cases by swapping the sideplate screws into their correct positions!
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Perform the 4-way cylinder stop function check. With cylinder open hold the revolver in your firing hand. Pull back the thumb piece and hold it to the rear. On the Ruger GP/SP rock the cylinder release forward and hold. Or on the Kimber/Ruger LCR use a punch to push the tip of cylinder locking piece back into the frame and hold.
Pull the trigger double action and watch the cylinder stop, it should drop below the frame top surface and pop back up, slowly release the trigger and the stop should move forward towards the muzzle and the back to the rear. Down, up, forward and back. Visually check bolt or cylinder stop function at every charge hole and finger-wiggle cylinder for side-wobble at each charge hole.
Check SA timing, making sure that the revolver is unloaded. **** each chamber SLOWLY in SA with the weight of gun resting in the palm of hand for drag. Note any failure to "carry up" and for bolt or cylinder stop to engage locking bolt notches prior to full ****.
Check hammer for push-off from full ****. If gun fails this test DO NOT BUY IT!
Drop hammer, hold trigger back and check cylinder for wobble both sideways and fore & aft
With hammer down and trigger held back again check cylinder wobble, observe hammer nose driven protrusion and retraction below flush with recoil plate as trigger allowed to rebound forward.
Check DA indexing, closing the cylinder and slowly pulling the trigger through double action. The cylinder stop should pop up into the stop notch and have a slight resistance after it is in the notch as the trigger is pulled to the rear before the hammer falls. This carry-up test needs to be done slowly, as a rapid pull can mask a “DCU” (factory term for doesn’t carry up) problem.
With revolver un-loaded, pulling the revolver action through vigorously DA while watching for positive trigger return and positive lockup of cylinder stop/bolt at each charge hole, before the hammer drops. Note any failure to "carry-up," or any "throw-by" i.e. over-rotation of the cylinder failing to lock up and rotating past a chamber, or sideways wobble.
Make sure the bolt or cylinder stop engages each locking notch the cylinder in place before the hammer falls. If locking skips on any cylinder then the cylinder stop and its spring needs to be replaced and a new cylinder stop fitted. Throw-by test should always be done by a rapid DA pull; because many times an empty cylinder lacks the rotational momentum of a much heavier full cylinder and will not show a throw-by unless the trigger is pulled quite rapidly.
Check cylinder fore & aft for longitudinal movement. On Colts this check should be made with the trigger held to the rear in the fired mode, then cylinder lockup should then be rock-solid.
Check barrel-cylinder gap with feeler gage inserted completely through the frame opening between cylinder and barrel.
PASS is the dimension when a feeler gage is protruding out both sides of frame window between barrel and cylinder, which does not impair a complete rotation of the cylinder by pulling trigger through DA six times.
Minimum PASS dimension is 0.003", because a tighter barrel-cylinder gap will bind the cylinder when a gun gets hot or if shooting "dirty" ammo, particularly reloads in which the bullets are too hard, undersized and inadequately lubricated...
HOLD is the dimension when the feeler gage is protruding out both sides of the frame window between the barrel and cylinder, binding rotation so resistance is felt in a DA trigger squeeze.
Maximum hold dimension is 0.008" on a new gun when measured with "rear gage" or fired brass in cylinder.
Customer service maximum is 0.009" after correction of any felt cylinder end play.
Today S&W accepts and will ship a 0.010" cylinder gap in a new gun. You don't want this. In my day the factory repair procedure was to fit a new “plus” [0.005" longer] cylinder. Gunsmith method requires setting the barrel back a thread and to refit cylinder after removing end shake, stretching the crane arbor on S&W or Ruger if necessary, or swaging a Colt cylinder bushing. A $200 repair job you want to avoid.
Guns having barrel-cylinder gap over about 0.010” should not be fired without being repaired, because they are prone to “spitting” and “bullet-in-bore” malfunctions, especially with jacketed ammunition.
End shake is measured by comparing the HOLD dimension measured twice, with and without empty brass or "GO" headspace gages in the chambers, or alternately with a 0.059" blade gage inserted between rear of cylinder and recoil plate or frame bolster. You can buy a “blade” gage from Brownells.
The least cylinder movement most people can “feel” is about 0.002.” If an S&W or Ruger and the cylinder "feels solid" with empty brass in the chambers, the gun is OK. Colt maximum end play is 0.003, so if you feel ANY end shake the gun is out of spec.
Most important on an S&W is that the strain screw in the front of the grip frame is tight, and that the screw has not been shortened excessively by Bubba to lighten his trigger pull! Skillful shortening as confirmed by 50+ ounces on a trigger pull spring gage is OK. Less than 50 ozs. may cause misfires.
Off-center firing pin indents which are off by more than ½ the diameter of the striker point are cause for concern, due to increased risk of misfires.
Learn the above and you will know more than 90% of people behind the gunshop counter.
