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Join Date: Jun 2009
Location: Northern Berks County, PA
Re: What is "working up a load"
Basically, it's experimenting with the variables until the load that delivers the desired performance is achieved.
In my case, I'm generally looking for MOA (or near to it) accuracy with as much speed as the rifle can safely deliver using a bullet that will perform as I intend upon reaching the target.
Example- the last rifles I did load development for were my 264WM and 35 Whelen. I wanted FAST but hard-hitting with the 264, so I selected a 140gr Nosler Accubond. The Whelen, I wanted HARD HITTING, speed as a nice add on if possible.
With the 264, I broke in the barrel on very light charges under 129gr Rem Corelokt's, then went to the AB's with RL33 powder. After messing with seat depth and charges, a few possible loads stood out. More experimenting, more shooting, and the last benched groups before hunting season were two consecutively fired groups at 300 yards that measured 2.1" and 2.2" respectively. This from a load giving right about 3200fps for a 140gr Accubond (muzzle velocity). That is a FLAT trajectory and a lot off oomph on the terminal end, too.
With the 35, I had almost no time with it before hunting season, so I had to be quick. No time for a break in.
With that one, I used a "round robin" method I got from a friend, and it worked.
In that case, I did SOME shooting at 100, but once I had a rough zero on the rifle and a few charge weights narrowed down, I went right to 200 yards for load work. Here I used a Speer 250gr HotCor for the terminal performance. I did a powder charge work-up, which meant 1.0gr increments, 5 different charges. Took that to the range, set up 5 targets on one target backing. Numbered the dots on the target, and arranged my loads in an orderly fashion, along with a notebook and pen. I would shoot one shot from each of the 5 batches, one one each target. Let's say I went from lowest charge first to hottest charge last in that string. Then gave the rifle time to cool to ambient temp, then did it again in reverse order, one shot on each dot, going hottest to mildest this time. The important thing is that each time I shot a given load, it was on the SAME dot as the others of the same load.
I kept repeating this process till charges were expended. This yields 5 targets of data that now are not biased by the order in which I fired the charges. No load had the benefit of a cooler or more clean bore.
That being done, I took the charge weights with most potential (two in this case), and did a seat depth profile. This meant I did the same process as above, but now instead of charge weights, I used the same charge weight and did several different seat depths, generally about 0.01" or 0.015" differences from batch to batch. Ran the round robin again, and one leaped out.
Loaded 10 of that one, took it back and verified it would repeat.
Put the zero on the gun, hunted with it, killed a buck in SC and a buck in PA with great results. The load I settled on went 2.5" at 200 yards for 4 consecutive shots. Speeds were in the 2500-2550fps range for the 250gr Speer bullets. For those loading for the Whelen, my charge wound up being 58.0gr of IMR4320. Since I was short on time, I was plenty happy with 2.5" at 200. This year I plan to do more load work with the Whelen and aim for MOA or less out to 300, with the same bullet.
The 264 claimed a doe in SC. I missed a buck with it, but that was operator error...lol.