D-Terminator Electronic Scale
By John Bibby
The idea behind ladder testing is to adjust one variable at a time, to determine a sweet spot for accuracy. The first variables to be checked are powder weights and seating depth. This assumes a bullet and powder have been chosen. If not; bullet weights, primer brand and powder brand are also up for grabs.
For such testing, all brass should be from the same lot and prepped in an identical manner. This is very important as we are attempting to make all things equal, except the one item we are intentionally adjusting. The first item that is usually tackled is the charge weight of a powder. This is done as it has the most impact and determines the effectiveness of a particular powder/bullet combination in your firearm.
For a random rifle round, using powder “X 123” the manual states a minimum charge of 22.0 grains and the maximum charge is 25.8 grains. From the reloading manual, we already know the approximate velocity of both the light and full load from the recipe. We don’t know is how accurate the loads will be in our rifle or where an accuracy node will occur.
For a new (to me) cartridge, I would run a double ladder for safety. My initial ladder would be to load 3 rounds each at 0.5-grain increments, skipping the minimum and maximum charge weights. This would give me seven loads to test. It would also greatly reduce the risk of a squib or an over pressure round. Each load would be precision measured. They would all be from the same brass batch, as well as weight sorted and identically prepped. Very strict attention needs to be paid to powder weight and cartridge overall length (COAL) when loading. The rounds should be fired over a chronograph to check standard deviation and velocity (a double check of proper attention to detail). Each load is fired from a solid front and rear rest, at a new portion of the target.
Check primers for pressure signs with each shot and stop regardless of increases in accuracy if signs are present.
As the powder weight changes, the groups will tighten up or grow in size. After the first round of testing, a trend should appear. In our theoretical first ladder, the groups might look like this at 100 yards:
22.50 gr 1.89”23.00 gr 1.75”23.50 gr 1.59”24.00 gr 1.34”24.50 gr 1.01”25.00 gr 0.69”25.50 gr 0.98”
In this example we see a distinct trend towards better groups as the pressure and velocity increase, but a possible break in the trend at the highest powder charge.
The second ladder would focus on that trend and do another 6-10 loadings in what appears to be the sweet spot. Given this example, I would load 3 rounds at 0.3-grain variances between 24.40 gr and 25.60 gr. This will confirm the sweet spot as well as confirm the accuracy node’s upper limit.
Finer ladder theoretical test data:
24.40 gr 1.08”24.70 gr 0.95”25.00 gr 0.75”25.30 gr 0.65”25.60 gr 1.23” and minor pressure signs
Once the powder charge is dialed in, the other above mentioned items could be looked into with this process. It can also be repeated for bullet seating depth, primer brand or even neck tension. Incremental changes will show improvement or degradation, as long as only one variable is changed for each ladder test. Each of the above mentioned aspects could have a noticeable effect on precision.
You have to decide how much work to put in and if your rifle, application or shooting skill can capitalize on the increasingly subtle adjustments.
The D-Terminator Electronic Scale is a high precision unit with the latest in load cell technology, 1500 grain capacity, anti-static wind shield, and included check weight. The large back-lit LCD display makes reading weights a breeze. The touch screen is easy to use and maintain. The D-Terminator Scale operates off of four AA batteries or with the included AC adapter.
- 1500 grain Capacity
- Accurate to +/- 0.1 grain or 0.01 gram
- Measures 5.5" x 6.75" x 2.5" (20cm x 17cm x 6.5cm)
- Platform: 3.25” Diameter (8cm)
- Automatic shut off ensures long battery life
- LCD Back-lit display with on/off switch
- Zero Function
- Mode Function
- Calibration w/ included 100g Calibration weight
- Attached Anti-Static Wind Shield
- Stainless Steel Powder Scoop
- Uses four AA batteries (included)
- Universal 110-240V Adapter (included)
- All electrical/electronic components of Dillon Precision equipment are covered by a one-year warranty from the date of purchase
The D-Terminator Electronic Scale also works great with the CED Ultimate Pro Powder Trickler for those of you making precision rifle rounds. Find out more about the CED Ultimate Pro Powder Trickler here.
WARNING: This product can expose you to chemicals including lead, which are known to the State of California to cause cancer and reproductive harm. For more information, go to https://www.P65Warnings.ca.gov