You all have helped me become a better reloader and a better shooter…

I love this sport.. Thanks Again..

The request also noted the needs to determine your ultimate goal. Our primary goal was precision (group size) because we wanted to use these for small varmints. Of course we also wanted the highest velocities we could get with acceptable precision.
(NOTE: Precision is the size of the group. Accuracy is the position of the group over the intended target. Accuracy is adjusted with sights and sighting, precision is how the firearm and a specific load behaves and can not be ‘adjusted’)

We choose bullets based on the purported terminal ballistics and available weights available. We choose powders based on recommendations from established load manuals and publications. For the 17Mach IV’s Todd Kindler (Woodchuck Den / Small Caliber News) provide tremendous assistance. Primers were chosen through testing during the development process. Velocity Standard Deviation and Extreme Spread were used as measures of uniformity in loading and powder performance, but surprisingly did not correlate to accuracy as strongly as I expected.

My quality background taught me that 30 piece (shot) samples give the highest confidence ratings for measurements. Since that was not practical we dropped to the next accepted sample size level of 7 shots per sample.

Sets of 7 rounds were made for each set of variables. The variables were:
1) Case Manufacturer (using fire-formed cases)
2) Bullet type – by each manufacturer
3) Primer type for each manufacturer (std vs match…)
4) Powder charge starting with the lowest recommended load with each set increasing by .2 grains each set (please remember this is a small capacity cartridge) for each powder type considered
5) Seating depth beginning with .020 off the lands and reducing to .005 off the lands.

Velocity and precision data was carefully collected for each trial, along with temperature, humidity and barometric pressure. (Barometric pressure did not turn out to be a significant influence – temperature did, humidity also did but to a much lesser degree). I transferred all of my data into an MS Excel workbook to keep track of the load details and results and conduct analysis. RCBS.Load seems like it could do the job, but I apparently am not smart enough to use the Construct User Load Data feature, in spite of hours (days?) trying. I do use the Target Tool feature for my group analysis and archiving.

We learned a lot:
* We learned to record and control the length of time between shots which turned out to be significant with a hot barrel acting differently than a cool barrel. Since this resulted in hundreds of shots (THE FUN PART!!!!)
*We learned to standardize our cleaning frequency (after each 7 shot group) and used fire-forming loads as fouling shots.
* We learned that different brass really is different – IE – Lapua brass shot differently than Remington brass with the exact same primer/powder/bullet combinations. Different loads had to be developed for each brand of case because the case capacity (and weight) varied noticeably between them. This caused us to modify our goal to also develop loads for each brand of case so they would have similar points of impact. The Lapua was by far the best and we worked up loads for the Remington brass that came as close as possible to the Point of Impact the Lapua produced – although slightly less precise.
* We learned that we had to know everything about the rifle that will be shooting the rounds under development. Finding the long neck in our chambers changed a lot about our loads and resulted in having to form cases from .222 instead of 221 Fireball and scrapping hundreds of fire-formed cases.
* We learned the value of the Sinclair bullet and case comparator in determining where each potential bullet needed to seated to control the distance off the lands. The bullet and case comparators are indispensable tools that provide the only reliable way to assure precision in case forming/resizing and bullet seating.
* We learned that the fire-forming groups of the long-neck brass were almost as accurate as the best loads we later developed, which happened to use the same powder and primer but the lowest charge.
* We learned that a good neck turner and 1/2 length resizing cut groups in half. A good neck turner meant consistency within .0005. we also learned that measuring neck thickness needed to be done on a tool with a pilot to get the effective neck thickness and not the thickness in one small spot. We like the Sinclair Case Neck Sorting Tool with the solid mandrel and no longer use our micrometer style gauges.
* We learned that most scales are not reliable enough for small calibers like the 17 Mach IV. Until we bought the Acculab Scale we were unknowingly being confused because of powder and case weight variation. Even our .223 loads improved once we started doing development using the Acculab. Once developed we were able to use, my favorite, an electronic metering scale like the Lyman DPS or a quality thrower for high volume reloading like the 223’s for our ARs.
*We learned we have a lot to learn……………

We still use the same 5 variables and 7 shot sample sizes when developing loads for our other rifles, excluding semi-autos. However, for Semi-Autos seating depth is based on a maximum length for the magazine and .010 increments down to slightly under (.030) the minimum of the recommended COAL from the reloading manual.

Our must have measuring tools for every caliber now includes:
Sinclair Chamber Length Gauge
Sinclair Cartridge Comparator
Sinclair Bullet Comparator
Sinclair Case Neck Sorting tool with an indicator that reads in .0001″ increments
Acculab Scale that reads to 2 decimal places so we can believe the tenth reading -

I apologize for going on for so long, but this is why I love this sport.