RoyB,   I need to do that.   I usually am sure of what I get off my chamber cast or when I do a compressed slug at different parts of the barrel for sizing purposes but when I order my next mold I'd like to have a bore rider of sorts and have thought that would be good confirmation of a my chamber cast.  I've never used either.    In your research did it matter what brand you bought or is a 'Harbor Frieght' grade of tool good enough in both those you mention?

Thanks Sam... appreciate the advice and links!

Guess it wouldn’t be too much of a hijack if I’d be using this ‘info’ when I paper patch…   That being the case, wonder if I could trouble you further:   Since I've always used a chamber cast for a mold and I've never used a pin or ball gauge I’m wondering if there is any trick to introducing the pin gauge into the lands for best accuracy in selecting the right one?   

Since my chamber is longer than two inches, and since I'm trying to get a good bore dimension right at the chamber, I’m just wondering how to get a good feel of things with the pins being only 2” long.   As with most things, experience usually comes with some good technique and I didn’t want to just drop a hardened pin down an old bore till one sticks.         

For background: I have an RCBS 416 350-FN I like ok in a Marlin Ballard 40-63.  The nose engraves well enough - maybe a little much if anything.    The lands best I can measure with calipers 0.4105 and the nose of a sample bullet measures that or under, so you’d think I wouldn’t be engraving at all, leaving me to think I ought to confirm with pin gages before I order a mold.    Other than being GC, the problem with this mold  is that I have to size it down 0.007 (.417 to .410) and I’d suspect I’m getting some distortion with that much sizing.  Sort of suspecting some bullet slump before I even pull the trigger though it’s fairly accurate as is.         Figure to have Tom cut something similar (maybe a little smaller meplate) at 345gr and of course lose the gas check. 

Wouldn’t mind sticking with my regular method -- but since calipers across the lands on a chamber cast can be off enough to impact good bore-riding nose dimension I figured (and evidence seems to bear it out) that I ought to use a pin gauge.

Visited the site, couple more ??:

What's the difference between Z and ZZ and English is for American system I'm thinking?

Also, do you use and handle.   Saw those advertized and wondered if that might address the 'technique' question since a handle would provide some 'feel' to the process with a pin shorter than your chamber length?

(You need to Login or Register to view media files and links) thing I've learned on the internet this week! Thank you!