With the mic, I found using just the ratchet, gave me results VERY repeatable, but .005" thinner than the calipers as I noted.
Taylor's Sterrets, when used exactly the same way, gave measurements .002" thicker than mine as his ratchet was not as strong as mine.
I find squeezing the tines of the calipers to give the best readings. This, after many decades of testing different methods.
We must remember the material is heavily squeezed between the lands, grooves and the ball.
Lyman's BP Handbook had a VERY good picture of the patch/cloth markings on a ball pressed into the bore and removed. It had VERY heavy cloth markings on the ball from the lands, yet still had cloth imprint markings on the ball from the bottoms of the grooves.
I have found my method of measuring, when adding to the balls diameter and equaling .003 to .005" LARGER than the groove to groove dia. gives me exactly the visual that Lyman had shown in the book noted. THOSE combinations seal ALL the powder gasses behind the patched ball.
We are all individuals and will use whatever suits us. Some like thumb stared loads andike to swab the bore more than shooting. Others like to be able to shoot all day with never having to swab the boe and get superior accuracy, unchanging, all day long.
Each to his own.
