Howdy
Cracked forcing cones were not a problem on the K frame 38s. They were made for over 100 years that way. Forcing cones did not start cracking on K frame revolvers until the 357 Combat Magnum came along. High velocity 357 Magnum bullets hitting the forcing cone could cause it to crack.
First, make sure the cylinder is not rubbing against the rear of the barrel. If it is out of square, the cylinder could be dragging on a few chambers, preventing the cylinder from rotating properly.
I have a test I do whenever checking out an old revolver of any make.
WITH THE GUN UNLOADED, putting a little bit of drag on the cylinder with your thumb, cock the hammer very slowly for each chamber until the hammer goes to full cock. Now, with the hammer at full cock, see if the cylinder is locked up properly. If you can rotate the cylinder a teeny bit to get the bolt to pop into the locking slots on the cylinder after full cock, the cylinder is out of time. Try this a couple of times for each chamber. Mark the chambers that do not time properly. I have found it is not uncommon with older double action revolvers for them to be a little bit out of time. Often times with this test the hammer cocks before the cylinder locks up properly. Now, repeat the test, but this time do not put any drag on the cylinder and cock the hammer vigorously. What happens? Does the cylinder lock up properly at every chamber? Often times, the momentum of the cylinder rotating will keep it rotating for a split second after the hammer goes to full cock and the cylinder will lock up properly for every chamber. I have lots of old revolvers that are a little bit out of time and the cylinder does not lock up properly at slow speed, but it locks up fine when the hammer is cocked vigorously.
Also, try this test with double action.
WITH THE GUN STILL UNLOADED, pull the trigger slowly, put put some thumb pressure on the hammer to keep it from falling. Try this test extra slow, and quickly. What happens?
I have lots of old S&W revolvers. If they are not badly out of time I go ahead and buy them, particularly if it is a nice old Smith that I want to have. I just remember to cock the hammer vigorously when ever shooting.
At the range, you can try this test with ammo in the cylinder, pointing it in a safe direction of course. The extra weight of bullets in the chamber often helps keep the momentum of the rotating cylinder, slightly overcoming the bad timing.
Bottom line, if I can get the cylinder to lock up properly every time with a brisk cocking action, or brisk trigger pull, I buy the gun. If not, I won't touch it.
If the cylinder locks up differently for different chambers, that probably means uneven wear on the ratchet teeth. if the cylinder does not lock up properly on all chambers, that may mean the hand is worn.
Buy this book:
http://www.gunbooks.com/sw.html
You can also buy it on Amazon. Absolutely the best book on the market about S&W double action revolvers. An entire trouble shooting guide in the back. The hardest part about replacing the ratchet is unscrewing it. Most of the time it is snugged up so tight you may damage it trying to unscrew it. The ratchet is brazed onto the ratchet rod. Too much pressure and you can damage it. One trick is to place three empty cartridge cases in three chambers, leaving empty chambers between the cases. This way the ratchet teeth will be supported as you try to unscrew the extractor rod. SPECIAL NOTE: Older smiths had right hand threads for the extractor rod to ratchet assembly. Later, this was changed to left hand threads. YOU MUST KNOW WHICH TYPE OF THREAD IS THERE OR YOU WILL BE OVER TIGHTENING THE ROD INSTEAD OF UNSCREWING IT. Extractor threads were changed from right hand to left hand sometime around 1960 -1962.
