.308 F-Class Load Development from Australia
by Germán A. Salazar
Thanks for writing, the shoulder is coming along slowly, and the F-TR shooting is definitely keeping my competitive urges satisfied. In the past two weeks, I had my lowest score (566-13) and my highest score (597-32) both on the same 500 yard range! Our conditions here in the desert of the Western U.S. can be highly variable, as I know they can also be in your part of the world.
I've only seen a handful of the HBC bullets here because there is no importer, but by all reports, they are the equal of the U.S. made match bullets. You have a great looking range there, the ability to shoot and develop loads close to the reloading bench is really valuable and it looks as though you're making the most of it. Creighton Audette's load development method is a useful tool and your target is a perfect example of it.
I agree with you that the sweet spot on your target is in the 46.5 gr. range. I'll assume that pressure signs were within the acceptable range. When I last used Varget with 155 gr. bullets, my load was right in that range also. However, I hesitate to recommend that as a universal thing because case capacity, primers, throat length and the barrel itself can have a significant effect on chamber pressure. It takes a careful workup such as yours, with an eye on the pressure signs, to be sure that the load is not only accurate, but also safe.
You mentioned that shooters in your area recommend a specific velocity range for accuracy with that weight of bullet. I hear that same sort of thing here as well, even from the highest level of the sport. Unfortunately, that really isn't a recomendation of universal applicability because rifles are just too different from one another for any such thing to be true - much though we might wish it were.
Individual testing, such as you've done, is the key to maximizing each rifle's performance. A good example is the load I used for the 597-32X yesterday; that load features a Sierra 190 at a relatively sedate 2600 fps. Despite the seemingly low velocity, pressure testing has shown this particular load to be close to SAAMI maximum allowable pressure for the .308; it's all a matter of powder selection. Although this load would be a poor choice for 1000 yards, it's an absolute hammer at 500 or 600 yards. Each competitor needs to put in the work, as you have, to find out what his rifle shoots best. There's no substitute for range time.
By the way, there might be something wrong with your camera, I noticed that both your truck's steering wheel and your rifle's bolt handle appear to be on the right side when we all know that they both belong on the left!