Testing Method of Powder Candidates

[Dimner]

In short, what is your method to efficiently test one powder vs another?

Usually, when I start a new cartridge, I have one powder on hand that is clearly the choice to start testing with. Both via anecdotal reputation, and calculations via QL/GRD. So I just get to testing with that one powder. Starting with a pressure test, then a horizontal impact test, followed by another one if necessary, and then seating depth. Followed, by fine tuning if necessary. That method has worked well for me so far. To get down to the 1/2" moa mark with sporting rifles.

However, in my current situation, I have 3 powders that are very well known to be successful with the cartridge and bullet that I will be testing. So... Is there a quick way, with let's say 15 or less rounds per powder, to determine which powder I should work with first? What is that method, and what is the manner of analyzing the results? I have access to a 100-500 yard range using a bench and will be using DIY wind flags. With this load development, I would like to get to 3/8 to 1/4" moa if my shooting skills will allow it.

 

[K22]

The process I have followed many years is quite simplistic, like me.

I have only ever reloaded for the so called "legacy" cartridges meaning standard commercial cartridges which have well established histories, e.g., 243 Win, 222 Rem, 22 250, 30 06, 308, etc.

So, powder selection for me is usually the easy choice since there is long established history of those powders that work well with a given caliber and bullet weight. A good place I found to start is with a powder that the published data, such a Nosler or Sierra states is the most accurate tested with that bullet. This of course is not 100% but I found more often than not it's a good place to start for a powder choice. My one exception is that I do not use ball powders anymore.

The component I found that is the most difficult to identify that will shoot varmint grade accuracy (1/2 to 5/8" moa) is the bullet. For whatever reason, some of the rifles I have owned just won't shoot a particular bullet well not matter which powder I try.

So, once I have chosen a bullet and powder, I proceed the conventional way of using published data, preferrable from the bullet manufacturer and try various powder charges, starting at the low end and working up. As everyone knows, you only change one element at a time in seeking the load to meet your requirements. I vary the powder charge amounts based on the powder capacity of the case.

Regarding your question of 15 test rounds, if you shoot 4 shot test groups that gives you 4 powder charge tests (16 shots) which should be enough to identify a potential load for more testing or not. I like 4 and 5 shot test group test as opposed to 3, but 3 can work also to bracket a potential load for further testing.

I conduct all test at 100 yards and select days with minimal wind and mirage. The accuracy of your testing will also depend in large part, on the quality of the front and rear rests, your ability to shoot with consistent shoulder pressure, trigger squeeze, etc. Trying to test too many loads in one range session never worked for me since shooter fatigue will set in resulting in inconsistent shooting and getting sloppy. It is also important in my experience to pace your shot sequence and maintain it consistently for all tests to avoid overheating the barrel and to achieve subjecting each test load as much as possible, to a closely identical bore condition.

Your goal of 3/8" and 1/4" moa is admirable for a sporter rifle but very difficult to achieve in my experience if you are speaking of consistent precision at that level. Even 1/2 moa is a challenge. Sub 1 moa for a factory sporter rifle is a reasonable expectation in my experience.

Before you embark on any extensive load development, I highly encourage you to make sure your rifle has adequate bedding, and the barrel is free floated. Without a properly bedded rifle, it is difficult if not impossible to shoot varmint level accuracy consistently.

Issues like testing various primers, seating depth, etc. can be pursued to refine the process sometime with positive results depending on how much money and time you want to spend testing loads. My process is governed by first establishing an accuracy standard that will meet my needs and once I achieve that, I am done testing since this is part of the sport that I hate.

 

[jackieschmidt]

My Ohler 35 Chronograph is always the key instrument in comparing similiar burn rate powders against each other.

however, at the level of precision and accuracy that I have to achieve in order to be competitive in my chosen Disciplines, the velocities are just a start.