How much money should we be investing in a scale that measures to 0.02 of a grain, often referred to as 1 kernel of powder? I used to think very important. Typically one invests a lot of time and money in reloading because it is a fun hobby, especially when the bug to improve your groups (accuracy) bites. Every now and then it is worthwhile to check the logic of what matters or else you will end up with drawers like this.
In reloading we never stop learning; in my instance mostly from experiences, meaning when I run into a problem I read-up on it; or when I observe stuff I think about its impact on reloading. There are millions of more qualified shooters than me who write on the subject, but I find most omit the practical side of reloading … the common sense, the stuff that matters.
Uniform velocity contributes to improved accuracy (fact). Velocity spread is a term used that quantifies the difference between the highest and the lowest velocity, and standard deviation (SD) the average difference between all shots measured. Double digit SD will show as a vertical string when shooting beyond 400 m (give or take).
There are many parts of reloading that contribute to uniform velocities such as having brass with equal case capacity (volume), equal neck tension, equal powder charge, same batch primers and powder, uniform bullets and so the list goes on. Generally the rule is consistency.
A material change in temperature has a material impact on velocity; potentially a greater influence in hunting than the other reloading factors (within reason). And here is my learning …
I loaded a batch of bullets for 3 different calibers (same day /same conditions) with meticulous effort in the various steps to have minimal velocity fluctuations. I shot when the ambient temperature was 24 C. All of the calibers recorded excellent velocity consistency.
I went to the range with the same loaded ammunition and repeated the test when the ambient temperature was 14 C. The velocity spread was minimal but with all 3 calibers the velocities were about 5% lower than recorded at 24 C (Labradar).
I did not embark on this test to validate the impact of velocity change due to temperature changes, but having stumbled upon the quantum of change I will perform the same test with the same bullets when the temperature is around freezing point. Unfortunately I did not keep my targets to check changes to point of impact.
This raises many questions such as bullet tuning (seating depth), ensuring your bullet leaves the barrel when the “node” / whip movement is stable for the longest period. Will the sweet spot shooting at high temperatures be the same sweet spot when shooting in the cold of winter mornings?
The rifle pictured below is a light weight 222. The gun (not me) shot 1 hole groups at 100 m with Berger 52 grains. A few months later with the same loaded ammunition the rifle would not group. We decided to change the barrel because we assumed the barrel was too thin (greater whip / node impact). Now we questioning ourselves, was the barrel faulty or was this the result of a change in velocity (temperatures) and we needed to re-find the sweet spot? A situation exacerbated in a ultra thin barrel?
Hunters should consider the material impact of temperature change on velocity and then determine how important is it for hunting ammunition to buy a scale that measures to the kernel of powder.
My basic principles for loading hunting bullets; if we can within reason (time and cost) eliminate velocity spread then that makes sense.
- Use quality brass which eliminates the need for neck turning (in future parts I will explain my logic of neck turning, the pitfalls vs. benefits for the occasional re-loader),
- Use the same make of quality brass. I sort by weight when developing loads, although it is not an absolute determination of case capacity I consider it better than doing nothing,
- For new brass debur flash holes (only once); some manufacturers like Laupa discourage this step because there method of making the flash hole does not create punch burs,
- Remove primers with a universal decapping die and clean primer pockets,
- Full length size, push the shoulder back 0.001-0.002″ from the fired brass head-space measurement (I never neck size, my logic in future parts). Buy and use head-space gauges if you don’t already have,
- Trim cases to uniform lengths. This step made quick and easy with Trimit or WFT equipment. It is quicker to trim the cases than measuring the case length, so I trim every time. I invest in a unit for each caliber, that way I know that I have case length uniformity year after year; and no set-up time needed.
- Do not mix standard primers with magnum primers. Bench-rest and long range shooters even keep to the same make and batch of primers,
- Case annealing is valuable but until I can purchase equipment that ensures a proper measurement of heat and timing I have chosen not to anneal (concern of doing more damage than good). The Powder Keg is tracking developments on equipment using induction where parameters can be input,
- Use a good scale; I have gone back to using my RCBS auto and 10:10 beam scale for hunting ammunition; a contradiction of an earlier BLOG where I punted electronic scales that measure to 0.02 of a grain.
- Use a quality powder for consistency although in SA the choice is limited due to availability and price considerations. When you have found the sweet spot of your rifle, in my experience, it does not matter what powder you use provided you achieve the same bullet velocity,
- Find the powder range where the velocity change in incremental load increases varies the least (accuracy nodes). At this point I know that the velocity change is the least sensitive to a small error in powder thrown (FLAT SPOT). I prefer the “flat spot” closest to the maximum load,
- Tune the bullet (seating depth) at the charge determined above.
- Re-check the zero of your rifle when hunting at significantly different temperature conditions than when your rifle was sighted in. If for no other reason … your own confidence.
Question the logic to become a better re-loader . I spend an inordinate amount of time in selecting products that The Powder Keg should stock and sell to ensure our customers have the best chance to buy right the first time. I have paid a lot of school fees and don’t want the same for customers.
Proving out – I placed a few rounds in direct sunlight. After firing I could see pressure signs on the brass (primer and extractor markings) validating that the heat on the brass created additional pressure. I load at accuracy nodes near maximums. In this instance the direct sunlight put my safe loads closer to the zone of risk.
Having great groups makes sense provided you understand the change of bullet impact in different environmental conditions and you practice in live positions vs. being a bench rest expert. If you can afford an electronic scale that does not drift then by all means buy it.
Alternatively, you can buy the Swarovski DS scope that makes all the climatic impact adjustments on your behalf. I have tried it on the range and it works well, but personally I do not like the size (40 mm tube) and for my traditional ways I do not consider it hunting. I don’t want to be fiddling with all the gadgets in the moment of a hunt; the animal will be the happiest of both of us because he will use those precious seconds.
