S&W K14-4 grove diameter

I slugging the barrel of my S&W K14-4 bit surprised that the grove diameter is .355" I thought should be between .357 to .358" is it correct?

Yes.

And it’s not a straight forward measurement to take.

5 grooves as I recall

1.  Select a gauge pin that just fits in your barrel.

2.  Since you have five grooves, measure your slug from one land to one groove.

3.  Subtract the gauge pin diameter from that measurement.

4.  Now add the numbers from #2 and #3, and that should be your groove dimeter within a reasonable tolerance.

This also works