Bench 7

Summation

Final inspection, loaded-round measurement, and process audit before ammunition leaves the bench.

Every bench matters. Basics returns the work to the SAAMI baseline. · Control and Tune add measurement depth when the work calls for it.
Bench 7 Basics
Summation
What you're doing and why
Bench 7 is where the logbook catches up to the ammunition. You documented the individual steps across Benches 1-6; now check the finished rounds against that record before they leave the bench.
1
Use a logbook

Bench 7 starts with the record. Across Benches 1-6 you have already documented components, brass prep, sizing, annealing, priming, powder, and seating. Now gather those notes in one place so the finished ammunition can be checked against the work that produced it.

You'll need Structured logbook
2
Inspect the finished ammunition

Inspect the finished ammunition against the documentation before it moves forward. Look over the rounds for primer seating, bullet seating, case-mouth condition, obvious damage, and anything that does not match the load record. Confirm the cartridge, rifle, bullet, primer, brass, powder charge, COAL, and CBTO target if measured. Anything questionable gets pulled before the Control measurements begin.

You'll need Finished ammunition + load record
3
Label the box

The box should identify what is inside without relying on memory. Record cartridge, rifle, bullet, powder charge, primer, brass, COAL or CBTO target, date, and the logbook reference. If the ammunition cannot be traced back to the record, the range data will not mean much.

You'll need Ammo box + label
Bench 7 Control
Summation
Loaded-round measurements
Control at Bench 7 uses measurements that can only be performed after the round is loaded: loaded neck diameter, CBTO spread, and loaded-round concentricity.
C1
Loaded Neck
Measure loaded neck diameter

Measure loaded neck diameter on finished rounds and record the minimum and maximum. With the same bullet diameter and seating process, loaded-neck diameter is the most accurate finished-round way to audit neck-wall thickness variation because the bullet is already seated inside the neck. This does not replace knowing your brass, but it shows what the loaded ammunition actually became.

Equation:
Loaded Neck Spread = Loaded Neck Max - Loaded Neck Min
Example:
0.2935" - 0.2928" = 0.0007"

Estimated per-side neck-wall variation can be approximated as Loaded Neck Spread / 2 when bullet diameter is constant. Example: 0.0007" / 2 = 0.00035".

You'll need Micrometer or calipers + loaded rounds
C2
CBTO Window
Measure CBTO spread

Measure the loaded rounds with a bullet comparator and record the shortest and longest CBTO values. This calculates the seating-depth tolerance window the ammunition was actually loaded to. COAL is still useful for fit and function, but CBTO is the better control measurement for precision seating depth.

Equation:
CBTO Spread = CBTO Max - CBTO Min
Example:
2.2465" - 2.2435" = 0.0030"
You'll need Bullet comparator + calipers
C3
Concentricity
Measure loaded-round runout

Measure total indicated runout on the bullet close to the case neck, not on the neck itself. Record the minimum and maximum TIR values and calculate the concentricity window achieved by the loading process. Competition seating dies can make a large improvement here because they support the case and bullet more consistently as the bullet enters the neck.

Equation:
Concentricity Window = TIR Max - TIR Min
Example:
0.0035" - 0.0010" = 0.0025"; max observed TIR = 0.0035"
You'll need Concentricity gauge
Bench 7 Summation
Summation
Process control audit
Summation turns the Bench 1-7 records into an audit of the loading process. A structured logbook organizes the data so the shooter can understand what each measurement means.
S1
Use a structured logbook

Summation is the process-control audit. It is more than writing down steps. The point is to understand what each measurement means, where it came from, and whether the finished ammunition confirms the process you used across Benches 1-6.

You'll need Sigma8 structured logbook
S2
Read what the measurements mean

Loaded neck diameter points back to brass neck-wall consistency. CBTO spread points back to seating-depth control. Concentricity points back to case-mouth condition, die alignment, seating-die design, and press technique. Bench 7 is where those signals are organized before the ammunition is fired.

You'll need Completed records from Benches 1-7
S3
Use Qual8 for full process control

Shooters who want the highest level of process control can use Qual8 to connect the Bench 1-6 process data, the Bench 7 loaded-round audit, and the range results that follow. That keeps later changes tied to the process instead of relying on memory or guesswork.

You'll need Qual8
Bench walkthrough
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Bench 7
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Full bench walkthrough — setup, technique, and measurement