The education continues, thanks for all the input. I have slugged two of my three rifles. Discovered one is a two land and the other is a five land barrel. This time I used the 1/4 oz oval fishing sinkers. A lot easier than trying to drive the 158 grain hard lead through.
I found an article that suggested that a wood dowel be placed in the barrel and the slug driven down on it so that progress was blocked and the lead would flatten to fill the barrel's groves completely before it was driven all the way through. And I did that. However, visually, it appears that the diameter of the slug is greater on the driven end than on the front and I am having a tough time getting readings that I have any confidence in. I have slugged each barrel three times. It is oblivious that I don't have any experience at this point. I may have to ask someone else to look at these tea leaves and read them. Anyone want to try?
Am I missing something here? The oval sinker flattens out wider than the barrel and it seems that it should be a good indication of the barrel diameter. There is excess lead that is trimmed off as the slug is driven into the barrel. The slug is not that difficult to drive through but it is greater than hand pressure. Think I am getting the total diameter?