Cartridge checks
Whether the catalogue's cartridges and loads agree with physics and with themselves. Every check here is arithmetic on figures the record already holds, so a finding certainly contains a wrong figure; the standards body (SAAMI or C.I.P.) or the load's maker says which one.
What it asks
Energy against bullet and velocity: a cartridge's typical energy is half its typical bullet's mass times its velocity squared. The three describe one load and must agree.
Pressure in two units: a maximum pressure stated in MPa and in psi is the same pressure, within rounding.
Dimensions no case can have: a neck or base narrower than the bullet it holds, a cartridge shorter than its own case, a rimmed case whose rim is no wider than its base.
A bullet against its name: a 9x19mm bullet is about 9 mm and a .45 ACP about 11.4 mm. Names that follow the case rather than the bullet, and flechettes that name the bore, are known exceptions.
Older than its parent: no cartridge is introduced before the cartridge it was made from.
Each load against its cartridge: a load's sectional density follows from its bullet's weight and the cartridge's diameter, and its velocity sits near the cartridge's typical, subsonic loads excepted.
How it is calculated
Figures on one cartridge record restate one another: energy from bullet and velocity, psi from MPa, sectional density from weight and diameter. The 7.62x39mm worked through:
Answer: 2010 J lies inside 1834 to 2241 J, so the energy, bullet and velocity agree.
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What happens to a finding
- Every run is published here as it happened, failures included, before anyone has looked at it.
- Each run is also kept as a report that lists what was fixed since the run before, what is new and what is still open, so progress is measured finding by finding rather than claimed.
- No check edits the catalogue. A finding goes to a person, who corrects the record by hand and cites what the correction rests on; the next run confirms it.
- A check id is never renamed, so a link to one keeps meaning the same question.