My mistake, I did use dial calipers, not a micrometer. I think the cylinder holes were clean enough, but I re-cleaned them and redid the test. Now I can get the .356-.357 bullets to slip through with hand pressure, albeit quite a bit of hand pressure.
I've read from Veral and others that cast bullets will shoot even if the throats are 1-2 thousandths over barrel diameter. I'm sure I will eventually have to slug the barrel, but it would be nice to know if there is a typical standard that most of these 686's fall into for barrel diameter.
The .357 is a somewhat of a new creature to me, as I'm mostly familiar with .44 and .45 dimensions. My 686 is about 4 years old. It's the 7-shot version, and I haven't shot it much (something I want to change).
A micrometer is hardly the correct tool for measuring the cylinder throats. The only proper tool is a pin gauge but darn few of us have those laying around so most use calipers. Using them properly in measuring cylinder throats isn't real easy tho and taking several measurements to be sure is normal procedure.
I have to wonder if they are just dirty as a reason for that size tho as I've owned a lot of S&Ws and have yet to see one that didn't shoot cast bullets well. Depending on the size of your barrel tho it still might. It's really the relationship between throats and barrel that matter not the absolute size of either and bullets should be sized for the barrel and hopefully the throats are just perhaps a half a thousandth over that.
