Re: Source for 308 range rod or indicator rod
If you have a Last Word, with a long indicator, use that instead of the range rods. Indicate the first spot as far in as you can reach ( about 2" is plenty ), and then a little further out, about 1", unless you cut off the stub, which you should anyway.
Repeat for muzzle end, just as accurate, probably more so, as the rod and bushing has some inaccuracy inherent in it. IE... if you want to measure something, do it directly, without adding any tolerance stack.