Please explain this to me...

[thefitter]

I saw this quote on another forum:

"...next time send the smith a blank hornady headspace bushing and have him cut an exact duplicate of the chamber and use that to measure fired and sized brass."

I asked the poster to elaborate but he has not. Can you guys explain it to me? Since I'm going to have a new barrel installed and I have a custom match reamer I'm wondering if I should do this. What would the benefits be?

Thanks

 

[CanusLatransSnpr]

If I had to guess, I would say have the smith cut a blank hornady headspace "comparator", or bump gauge if you will, with the same chambering reamer used to chamber the barrel. Then it would fit the fired brass exactly for measuring purposes.

Mike

 

[alf]

Better yet, have the smith run the reamer part way into a barrel stub. Different names for it such as a neck-n-seat gauge, critter, etc. You can use it to set seating depth in a new barrel, and also to measure shoulder bump on fired cases.

Mo better than the Hornady tool.....

 

[dtucker]

Alf hit the nail on the head. That is the way i have them done and it works great.

 

[BoydAllen]

Another name for the barrel stub with a partial chamber is a "gizzy". In any case, it should not include the point of the shoulder, and should include the full throat, and be long enough that no bullet will protrude from the end. both ends should be square to the bore.

 

[thefitter]

I should have known this was gonna get more complicated.

Is it safe to assume that any competent/experienced gunsmith will know what I'm talking about when I ask him for a "gizzy", "neck-n-seat gauge", "critter", etc.,?

 

[lmorrison17]

I would say a competent "BR" smith will know what a gizzy is.
Larry

 

[kjcpoint]

I call it a widget? I can send you an example if you wish to take it to your smith?

Kyle

 

[thefitter]

Thank you for your kind offer, PM sent.

 

[spclark]

Simplify things & just call this device what it is: a "chamber proxy" made with the same reamer used to chamber a new barrel, run into a cut-off section if the same barrel. Doesn't need to include any portion of the chamber sides but should include at least half the depth of the case shoulder cut.

Many 'smiths will do this as a matter of course without your needing to ask.

Great item to have for checking seating depth and keeping an eye on throat erosion during the life of the barrel.

 

[wapiti25]

I use mine to see the shoulder demension both fired out of the gun and when bumping back. You measure over the "gizzie" with a case inserted, from the bsae of the case to the far end of the gizzie.

 

[BoydAllen]

One more detail....you should knock the primer out of the fired case before using any gauge to measure if before sizing, so that the primer being slightly above the head, or being even slightly cratered does not become part of the case measurement.