I shoot 5 or 6 at the same target and color the tips different with a sharpie marker to correspond with the charge. A red sharpie leaves a red ring on the hole in the paper target.
Here's the best demo I've seen.
Ladder Testing | Shooters' Forum
I've been asked to start a thread describing Ladder Testing. The fallowing is my own description, recommendations, and example of
Ladder Testing:
Ladder Testing is the loading and firing incrementally up a charge ladder, firing 1-round of each increment at the same Aim Point. Assessment and discovery are then made from the vertical dispersion between the increments in relationship to each other.
Ladder Testing is not exquisite to charge increments only, and many use the method for other developmental aspects such as conducting: Seating ladders, Neck-tension ladders, and other load development aspects incrementally, with the assessment and discovery solely based on vertical dispersion between the increments as well.
The running of 2 ladders back to back round robin style is another popular way of conducting ladder tests, for further confirmation and proof.
Some even run more then 2 ladders back to back, in shortened versions, for fine tuning. Which is a very popular method for several 1000yd Benchrest shooter's that I know.
Below is a
15-shot Ladder Test conducted at
450yds from a Browning X-Bolt 270-WSM with 130-BT Nosler/RL19/CCI-250/Win brass. Below it is the velocity and vertical measurement data from the test and a "classroom" type description of how I assess and conduct Ladder Tests:
Below is the ladder target drawn to scale onto a chalkboard representation:
Below is node assessments determined by the relativity in vertical dispersion:
Below is chalkboard representation of the increments in a vertical line:
Below again, is node assessments of the vertical line representation:
Below is the procedure steps I make to conduct my ladder tests:
Below is the "Plot Sheet" made when running the ladder test:
Other recommendations and suggestions:
- Hang the target to be used for Ladder Tests as level and square as possible.
- Plot the POI placements to each bullet hole to its referring Ladder number.
- Starting with the lowest charge, working up the increment ladder in succession.
- Allow appropriate time between shots, to plot each shot, record the velocity, assess pressure.
- Fire all increments at a common barrel temperature baseline.
- All shots to be fired at one same Aiming Point on the target.
- Recommend 300yds minimum for conducting Ladder Test.
- An "infrared heat gun" is what I use to monitor my barrel temperature.
- White poster board or minimal marked target paper, work best for spotting at distance.
- Camera set to record, colored bullet ogive's, reactive target board, target cam systems, etc. all work good for alternatives besides optic and optical spotting/plotting.
- Wind drift has little effect to the assessment outcomes to ladder testing, since vertical dispersion is the sole discovery aspect. Reference all assessments by vertical dispersion only.
Utilize the barrel cooling time between each shot to record, assess, and return the rifle to the same POA and battery position. Do not load the next round until your ready to fire it, to prevent the round from being heated in the chamber (oven effect).
Of the advantages to a Ladder Test, the efficiency in discovery of Maximum Pressure for the cartridge and chambered barrel. Some ways to assess for
Pressure Signs are:
<> Amount of extraction force needed when lifting the bolt handle to extract the cartridge.
<> Reading of the primer, for "flatness", "cratering", and for leakage around the primer.
<> Visual assessment of the case head for "brass swiping" and scratches from extraction.
<> Visual assessment of the case head for brass flow and markings of an extraction plunger.
<> Measurements for the amounts of case stretch
<> Abrupt increase to the amount of recoil felt.
<> Assessment of the chronograph data.
Once we have identified a maximum pressure point, we then stop the ladder test at that point, for safety and risks of continuing any higher. And the charge level being identified as our "found maximum".
Load and test safe.....
Donovan Moran
Last edited: Feb 6, 2016
