Patch thickness measure

[Erwan]

I use a Starrett vernier mic. after affirming the mic is calibrated, I turn it until I hear 3 clicks. New pillow ticking has sizing in it, so you will never get an accurate read until all the sizing has been washed out. As long as I can recover my patches that show no blow out, and I have good accuracy, I don't care what the actual thickness is.

Me too.

 

[Dale Allen Raby]

I've tried different materials (silk, cotton, linen), different weaves, different thicknesses and different lubes over the years. As long as the patch material is anywhere from .007 to .015 or so with a ball that is .010 under the bore diameter, I have not noticed any real difference. I don't like tight fits because they are hard to load and some almost require a mallet in the possibles bag.

I probably have a lifetime supply of patches, but if I ever use them all up, I will probably go back to T/C prelubed patches... hopefully about .010 thickness.

That said, I have a few guns that simply will NOT shoot PRB at all.

 

[45man]

Don’t forget that whatever your ball diameter and lubed patch thickness is, when you test fit this PRB one inch into your rifles muzzle. Then wait a minute for the cloth weave to thoroughly emboss into the ball’s circumference/equator.

Remove the PRB via the slide hammer action using the short (~8”) brass rod you’ve previously inserted into the barrel and gently slid to the bottom.

The removed ball should show a belt of patch weave marks.
The pattern of the cloth should be embossed all around the ball in a connected series of marks.
These marks show deeply embossed over the lands and much more lightly embossed over the grooves. The groove areas must show embossed marks too.
If their missing over the grooves the PRB combination is too small in overall diameter.

In my GPR I had to move up from a .530” ball to a .535” ball with my chosen patch material thickness.
The patch cloth was measured new, twice hot washed and lubed.
Measurements were taken at each of these cloth conditions with a caliper and micrometer.
Frustratingly different thickness were record at each step, I choose to go with the result from the washed and lubed cloth and adjusted my ball size to get the above mentioned cloth weave pattern embossed all around on the larger .535” ball.

This is the correct way to fit a patch. You should see patch weave at the groove spots too. That is the best seal.

 

[david w]

View attachment 198194
Me too.

For those who think they can judge thickness by thumb pressure, consider 98 a pound, 98 year old lady to a 21 year old 230 pound weightlifter. Not only is your strength greater, but you sence of feel is different. The little thingy on the end of micrometers was put there for a purpose, consistency of pressure.

 

[ohio ramrod]

I measure my patching material with a firm tightening of a micrometer. Firm, not "C" clamp tight.

 

[david w]

I measure my patching material with a firm tightening of a micrometer. Firm, not "C" clamp tight.

There is a reason micrometers have that little click thingy on the end. It is designed for consistent measurements. Tightening by "feel" will vary by individual.

 

[Dale Allen Raby]

Not all micrometers have a friction ring... and as they get older, that friction varies. I prefer the old Browne & Sharpe ones without the friction ring.... but sadly, I haven't seen of of those since 1975 or so.

 

[ohio ramrod]

Not all micrometers have a friction ring... and as they get older, that friction varies. I prefer the old Browne & Sharpe ones without the friction ring.... but sadly, I haven't seen of of those since 1975 or so.

When my oldest boy went to General Motors Institute he came home for the first break and said he needed a new computer since all of the other students had newer ones than his. I told him different people would be ahead in different areas, I asked him : "how many of the others could read mic's and use indicators as well as he could?" He replyed :"they all could, they just push a button and read out the value in either metric or english, they don't use antiques like you use.