Optimising Loads For F-Class
Optimising Loads Overview
Starting out in F-Class target shooting can be a daunting task but once you have the basics of shooting at the different ranges mastered its then time to optimise your equipment and ammo.
Shooting combines both art and science and even the best components if not skillfully assembled and tested will fail to reach their potential. There is not any single magic formula or theory that will work with every rifle and ammo combination. What there is available to us all is a wealth of information that will lead us to find the best combinations of components for our application.
This article is about making ammunition that gives repeatable accuracy in the rifle and caliber you have chosen to compete with in F-Class. Accurate ammo removes a very large variable from achieving consistent high scores so its worth the effort required to achieve the result.
The purpose of this article is to piece together internet resources that will be hyperlinked in the text. These linked resources I have personally used and still refer to regularly. They combine to give any shooter looking to improve the accuracy of their ammo all they need to know to achieve the best possible accuracy.
These 3 shot groups at 100 metres were shot at the end of the load optimisation process.
F-Standard Ammunition Components (Taken from the NRA Aust 2008 Standard Shooting Rules)
3.4 Ammunition and Components (SSRs)
3.4.1 Ammunition acquired through the NRAA for State association distribution to its members shall be used in all
Check with SARA (SA Rifle Association) for which projectiles are available for use. At the moment the 155gr HBC BJD's are the most popular for 7.62mm and the 80gr Hornady Amax for 5.56mm. The projectiles you decide to use must be acquired (purchased) through the State Association. (SARA Store)
The Hornady Amax projectiles have a pointed plastic tip that greatly enhances the ballistic coefficient and gives it a real advantage compared to the Sierra MatchKings in the 5.56mm range.
Note: Meplat trimming and/or pointing for F-Std while desirable for bullet uniformity, needs to be addressed through the State Associations, as clarification is required on the rule's interpretation. At present it is unclear whether it can or cant be used, so the safe option is to seek clarification of rule 18.104.22.168 before meplat trimming or pointing your bullets.
Powder choices are limited but brass cases and primers are left for the shooter to choose for themselves. New cases should be properly prepared prior to using in competitions if you are after the best possible accuracy. Follow this link on brass preparation for an excellent guide on how its done.
F-Open Ammunition Components
There are no restrictions on component selection for ammo, the only restriction is on caliber size. Any rifle up to and including 8mm is suitable for F-Open. Some ranges are restricted by only having approval for 7.62mm caliber. So it would pay to check before going to an unfamiliar range if you have an 8mm rifle.
Popular calibers are 7mm (straight 284W), 6.5 x 284, 6.5 x 55, 6.5 x 47L, 6-6.5 x 47L and 6mmBR. Some use the 6mm at the shorter ranges and the 7mm at the long ranges. I use the 6.5 x 47L at all ranges.
Projectiles in these calibers reach exotic BCs with the 7mm Berger 180gr VLDs having a ballistic coefficient of 0.659 and even the 6.5mm 130gr VLDs reaching 0.552.
Not much needs to done to these projectiles but batch weighing, meplat trimming and/or pointing will enhance uniformity. Info on trimming and pointing can be found using the hyperlink.
Optimising Your Load For F-Class
Once you have picked out the powder, primer, projectile and prepared the brass cases, optimising requires a method to test the accuracy of the load in your rifle.
Tools to make testing easier are listed below
To optimise loads you need to know what depth to seat your bullet and the Hornady OAL gauge will give you the Overall Length of the cartridge with the bullet touching the barrel lands. The match bullet seating die allows accurate 0.001" adjustment for seating the bullet to whatever measured distance you want.
Choosing The Method
- Optimal Charge Weight Development
- The Incremental Load Development Method
- Optimising VLD Projectiles
- Optimal Barrel Time
- QuickLoad Software
Choosing a method is easy, have a look at what has been written and tested, then find one that makes sense to you and that you can follow. Many roads lead to the same destination but its important that you understand and have the equipment necessary to apply the method you choose.
I have had success with using the Optimal Barrel Time method and by using the measured velocity from my rifle in Quickload to calculate barrel time. It has enabled a very quickly derived ball park optimal load, that then just requires a little fine tuning. I have fine tuned using a shortened version of The Ladder Test and using Berger Bullets, Optimising VLD Projectiles paper.
Whatever method you choose, I wish you success and look forward to seeing you on the range sometime in the future.
(Ian Pavy 20-5-09)