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Concentricity gauges


srvet

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Could I pick the UKV collective brain please. 
Like many others I strive to obtain the best results from my handloads and aim for concentric ammunition. There seem to be two methods of measurement of concentricity, those that reference off the case wall such as the Sinclair comparator and those that reference off the cartridge long axis by centring meplat and case head such as the Hornady. Is one better than the other? It strikes me that a non concentric case (eg small dent) could result in an indication of excessive runout whilst the bullet could be perfectly aligned with the long axis. Would the Sinclair type be better for assessing case concentricity and the Hornady better for assessing concentricity of loaded ammunition?

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29 minutes ago, srvet said:

Could I pick the UKV collective brain please. 
Like many others I strive to obtain the best results from my handloads and aim for concentric ammunition. There seem to be two methods of measurement of concentricity, those that reference off the case wall such as the Sinclair comparator and those that reference off the cartridge long axis by centring meplat and case head such as the Hornady. Is one better than the other? It strikes me that a non concentric case (eg small dent) could result in an indication of excessive runout whilst the bullet could be perfectly aligned with the long axis. Would the Sinclair type be better for assessing case concentricity and the Hornady better for assessing concentricity of loaded ammunition?

I use the the Sinclair gauge (for what it's worth - not much I feel by results) and gauge the bullet run-out  after testing the case is concentric.  A quick application of the calibrated thumb and bullet run out is fine.  If the case was 'bent' it would not gauge centred and if the neck axis was offset to the axis of the case it would not gauge centred.  The Hornady system seems overly complex and in my experience you certainly don't need the mechanical advantage of a screw to move the bullet in the neck - including .338LM.

Personally I feel it's the source of non-concentricity that need correcting - bullet seating die and ram being the contenders

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I have often said that I would give my concentricity gauge  to anyone who knocked on my door and asked for it. I have the Hornady and it worthless. Even using cheap Lee dies I'm within their standard of .003" run out and indeed, straightening out ammunition didn't produce any results I could see on paper or steel. I bought the Hornady on a lark (gift cards) and it was the straightening device that got my interest. With out it, the tool is just showing you something that, by in large, you can't do anything to change. You can buy different dies or do something differently, but that is a deep rabbit hole to fall into. FWIW, my FL resized cases with bullets seated to full depth gave the best run-out readings  for standard commercial dies.~Andrew

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