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Despite the popularity of semi-automatics, there are plenty of revolvers around, some for cowboy-action shooters and others used for home defense and concealed carry.
Some revolvers have been made by manufacturers have cost-cutting modifications, but are not as good as the old made-for-hard-use 'wheel guns'. It is true modern revolvers that are made with CNC machines are consistent in its making over the older firearms, but the material used is less quality. That is pretty much the story of many things manufactured today – cost more but not made as durable. Automobiles are good examples, the sheet metal being thinner on a modern vehicle that that used on cars made in the 1950s; their cost increased because of the cost of steel and the tech marvels installed.
The following is a review of function testing and maintaining revolvers, specifically the Smith & Wesson, but applies to most double-action revolvers.
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The action of the revolver is simple. When the trigger is pressed the rear of the hammer is is raised from the rest stop. The cylinder stop drops to allow the cylinder to turn. The hand rises to engage the extractor ratchet and the cylinder begins to rotate. The cylinder stop engages the cylinder, then the hand drops off the extractor ratchet as the cylinder locks. The hammer drops as the trigger reaches the end of its travel and releases the sear. The hammer moves forward and the revolver fires. As the trigger is released, reset engages. The hammer moves to the rear. The hammer is back at the rest and held in position by the rebound slide. The cylinder stop and the hand reset.
For the function check, first as with any firearm check to make sure it is not loaded. Press the trigger and check the double action trigger. The trigger compression should be smooth with no hitches and without any roughness in the action. The double action trigger should be consistent each time the trigger is pressed. Next, cock the hammer for single-action operation to check that mode. The single action trigger should release smoothly. Make sure the cylinder locks into the bolt stop as the hammer is moved to the full cock notch. When testing the single action operation, cock the hammer slowly, keeping an eye on the bolt stop. The bolt stop should lock into the notch in the cylinder just before the hammer reaches full cock. Test each cylinder in this manner. Sometimes the timing is off on one of the cylinders, which can result in what is called end shake or a bent crane. When testing the double-action timing the bolt stop should lock just as the hammer falls. In this way the bolt stop and hand will also be tested with this procedure.
When testing the double-action press, keep the trigger down and rock the hammer back. Rock the cylinder and see if there is excess motion. The cylinder may have some play, but too much is bad. Move the cylinder laterally and check for play. Only a few thousandths of an inch in movement is acceptable.
Release the trigger and let it move forward. This tests the trigger reset. If your revolver was bought used or considering to buy one and using the function check procedures aforementioned, check to see if the previous owner has clipped a coil or two from the rebound spring, this test will reveal it. A few sharp pull on the trigger will indicate if there is any problem. The trigger should return to position after each brisk trigger press. A tight trigger action is good; too light or inconsistent, it is a sign of trouble.
Continuing with the test, a portion of the function check that is sometimes forgotten, is to cock the hammer in the single action mode and apply upward pressure. If the hammer falls forward there is a serious problem, usually because someone has ground the connecting surfaces of the hammer too much – this is a dangerous situation. When performing a trigger job, someone who does not know what they are doing may grind and not keep the original angles. In most cases, grinding is not required, just some polishing on the hammer contact points.
Now check the barrel cylinder gap with a feeler gauge. The cylinder and barrel gap should be o.006. On modern inexpensive revolvers the gap is often larger. A measurement of 0.010 is not a problem.
There are two types of barrel cylinder gap to measure. After cartridge ignition the cylinder is pressed back by recoil against the recoil shield. In this position the barrel and cylinder gap is at its widest. This is where lead spitting and the most velocity loss occurs. When the cylinder is not under pressure there is a different reading. The difference may be 0.002 of an inch. If more than 0.005, end shake is in play that can be fixed with bushings. Few modern guns are as tight as older ones.
When checking headspace look to the center pin at the end of the ejector and pay attention to where the contacts the recoil shield. Use a spent case to check headspace by loading chambers because spent cases from the same gun will slip back into the cylinder and chambers, The distance between the case head and the recoil shield should be about 0.008 and 0.010 should be right. Otherwise purchase a 'Go' and 'No-Go' gauge, but they are not cheap.
A cylinder gap as high as 0.012 or greater it may misfire; especially with many .45 caliber revolvers.
When the revolver is opened and the cylinder swing out on the yoke, the motion should be smooth and free of binding. Press the ejector button. The ejector rod should be tight. Sometimes they work loose after firing, so should be tightened periodically. The cylinder should rotate freely when the barrel is either pointed upwards or downward. There should be no gritty feeling when rotating the cylinder. When closing the cylinder it should not touch the rear of the frame. Slowly close the cylinder and ensure that the yoke lines up properly with the frame and does require force to close. The cylinder should not contact the barrel when the cylinder is closed and should rotate freely on its axis.
The safety features video by Midway:
This last video, by Midway, concerns Smith & Wesson and inspecting a used firearm that you may considering to purchase; applied to most other revolvers as well.
The revolver is an interesting intricate of precise workmanship, Smith & Wesson being no exception.