I could use some advice on this. I have an old N-frame S&W .357mag (pre Model 27) that basically has no cylinder gap.

When the gun is perfectly clean and cold, you can just see the tiniest bit of light through the gap, after the gun heats up, this closes and the cylinder hangs up.

Is this as simple a fix as adding shims? I have a small amount of end shake, if I added, say, .006" worth of shims, that end shake would be all but gone.

Do I need some end shake?

Alternatively, I've seen videos on YouTube where people enlarge the cylinder gap by honing the end of the barrel. Why would this be better than shims?

If the gun needs serious work, I'll be glad to send it to Frank Glenn, who has done great work for me in the past. But if I can dial this in myself with a couple of shims, I'll give it a try.


Thanks!

If your gun has endshake, are you measuring the barrel/cylinder gap with the cylinder held rearward as far as it will go? Have you measured the gap with feeler gauges to know exactly what it is?

The smaller the gap, the better, but if it is causing binding then that is a problem. A good gap would be about .004, but sadly most S&Ws don't even come close to that tightness, only Colts.

So if you have some endshake, adding enough shims to take that shake out should also help with the gap. That is what I would try. I got shims from Triggershims dotcom for my SAA and their prices are great. Pretty sure they make for Smiths too.

Ideally you want 0 to .001 endshake. Just enough for the cylinder to turn freely. If you set the endshake correctly the cylinder gap will probably take care of itself. For shooting only jacketed bullets you can be OK with .003 - .004. For lead bullets, or some of both, you need about .006 gap.

Theoretically you want 0 endshake and .001 cylinder gap. Unfortunately there are other factors involved so that won't work in real life.