You just got your new rig home and are ready to get it shooting its best. But what is a way to get it dialed in without spending a fortune, burning up the barrel and taking multiple trips to the range?
This was a problem I faced years ago when I made the plunge into LR hunting. The most common method was to load up a bunch of ammo while varying one thing (usually powder in 1/2gr increments), shooting a few 5rds groups and 'working up'. When the best load was found, some other changes might be made like powder, bullet, primer, seating depth, neck tension.
I did this for a few rifles and burnt through large quantities of ammo and barrel life. Started looking for another way.
What I found was the Audette Ladder test. You fire 1 rd at each powder increment at longish distance and look for where the shots cluster. The idea is that as you approach a node, the barrel will be less sensitive to powder change and all the bullets will land in a cluster.
It wasn't something that I thought would be too reliable, as I tend to shoot in the wind and that can move things around enough to cloud the results. Also, my present method showed that some rifles' sweet spot is very narrow- narrower then the average powder step used by many shooters.
My solution was to combine the strengths from each method to find a way to get my rifles dialed in while shooting the least number of shots. Also, the method eliminated the need to vary seating depths which can be problematic in a mag fed rifle. Varying neck tension was also eliminated as the ammo had to hold the bullet well enough for field usage.
I keep these two parameters constant in my testing. I use the Lee collet neck die for my neck sizing and this provides around 2 to 3 thou neck tension.
Before we discuss the process, you need to take these steps otherwise your results will not be dependable.
-The rifle should be properly bedded. Even the alum chassis stocks, all nuts and bolts tightened down and the trigger set for the lightest pull that you want to use.
-All test should be done at 200yds. You will not see the variations in the testing at 100yds. 300yds is also good but wind can start to play a larger role then desired (calm air is always the best, but not always possible). Use as many wind flags as possible - a stick with 2ft of flagging tape is all you need.
-Use fireformed brass that has been prepped as well as possible. You will be varying your loads in very small increments and unformed brass can mask these effects. Plus new brass is not always straight which is resolved with fireforming. I use a light charge of pistol or shotgun powder behind some cream of wheat or cornmeal to form the brass. Size the brass the way it will be used in the field.
-Use accurate bullets like Bergers/Hornady Amax/Sierra MK's, temp stable powders like Hodgdon Extreme, match primers. Proven components for the chambering you are using.
-A very accurate scale. This is really critical to your success. For a large magnum, holding to ± 0.1gr is ideal. For a 308 and 223 sized case, less is better. Yes, I have seen effects on groups and stringing with very small increments in powder.
-Ammo with little to no runout. In my previous article on loading for LR shooting, I covered tips on the loading process to maximize your accuracy. Runout, or bullet wobble, really hurts your accuracy potential and VLD bullets are very sensitive to this. Less is always better.
- Solid rest/bench and stock set up. We are testing the load, not the ability of the rifle or rifleman to shoot. Anything to eliminate shooting error should be used.
- Quality optics that let you see at least 1/8" at 200yds (the smaller the better). That is pretty much a given in the LR game as we tend to use high mag scopes with better optics. The article on choosing and testing your scope for LR shooting can help you with your choice and setup.
- And most importantly - shoot with as little wind as possible and use flags. This is worth repeating....