Question

[Reg]

Just one of those things I never paid attention to--- there were many actually but -----

A number of years ago there was much ado made of the internal capacity of cases as measured in the weight of a water filled case.
Without appearing too knot headed just what was that all about ? What were they trying to equate to other than similarity of capacity. Was there a concept of internal capacity vrs. bore diameter, I.E. such as over bore capacity ? Were there ideal parameters ?
Was there a relationship as to load density ?
Can anyone refer me to reference material.
Have tried to bring it up in reference but nothing shows.
Moderators please feel free to move this if in wrong area.

[runfiverun]

it gave you a weight in grains of water.
powder has a specific gravity also [usually in the 0.9sumthin area]
anyway the water gave you an idea on case volume so you could use a powder that would give you a 90+% case fill.
all the other stuff you mention has a relationship too only not tied to the water weight.

[HeavyMetal]

As RFR put it it was a basic measure of case capacity, much military ammo is smaller internally than commercial brass so hot loads transffered "Willy Nilly" between case type can and will get you in hot water pronto!

For me the eye opener was with 9MM brass!

as much as 4 to 5 grains difference in case capacity can be big with full loads of Bluedot, LOL!

For a good read theres a paragraph or two in Ken Waters 9mm rewrite, if you can find it, in his pet loads book.

9mm case's have the worst track record for QC Ken found case lengths varied .020 in a single box of 50 rounds factory ammo!

[MOcaster]

Handloader's Manual of Cartridge Conversions has all the maesurements, including case capacity in water. Hamilton Books has it for $10. It is worth it. Every reloader should have a copy, even if they never plan on converting cases.