As part of our practice regimen, we shoot a lot of rounds at 200 yards from various unsupported positions. Gilt edged accuracy is not required, so our objective is to develop a practice load utilizing a ball powder so we can rapidly load our ammunition on a progressive press utilizing the built in powder measure. This approach can also be utilized by those using a single stage press and a powder measure versus weighing individual charges – you’ll still save a lot of time. We decided to work up a 6.5×47 Lapua practice load utilizing Accurate 2700 (a ball powder which should measure consistently) and the moderately priced 123 Lapua Scenar.

Note: As with any discussion pertaining to reloading practices, use common sense. Your results will not necessarily reflect our results due to any number of variables, and a safe load in our rifles could be a dangerous load in yours. If you are uncomfortable or unsure what you are doing, please stop and seek out advice from those with more experience.

Utilizing the methodology outlined in Load Development (Part 1 of 2) we put together 10 loads in .3 grain increments. Based on prior load development with the 123 Scenar and other powders (H4350 and Varget) we hypothesized that the optimal load for the 123 Scenars would be in the neighborhood of 2950 fps (turned out we were right). Knowing that 40.8 grains of Accurate 2700 gave us around 2900 fps in the past, we started our test loads at 40.2 grains all the way up to 42.9 grains. Our intention was to capture a low and a high accuracy node and we were successful.

Based on the results illustrated in the graph below, we believe the optimal load resides in the neighborhood of 41.1 to 41.4 grains of Accurate 2700 (on the high side) and 40.2 to 40.5 grains (on the low side). Now we could develop some additional loads in .1 or .2 grain increments to nail down the optimal load exactly, but our fine tuning of the load does not have to be a gating activity. All the loads we tested were adequate for what we want to do in practice. Furthermore, we are going to be using a powder measure and charges are going to vary above and below the target charge weight.

Below are the groups we shot with the various loads. At first glance, one might be drawn to the 41.7 grain load but it had the highest SD and ES of the lot. As discussed in Load Development (Part 1 of 2) these variances will show up at distance. The 42 grain load seems attractive, but it is nestled between two loads with high SD and ES. Since we are going to use a powder measure and Accurate 2700 is more temperature sensitive, we don’t want a situation where variances in charge weight or temperature take us into a scatter group. The 41.4 grain group had the lowest SD and ES of the lot, but one thrown shot made it the largest group. Again, we’re seeing the human element come into play in which case it’s so important to rely on the data. Finally, 40.5 grains seems like a promising low accuracy node that should be easy on the barrel. I fully expect that when we work up additional loads in smaller increments from 40.0 to 41.7 grains, our data driven approach will be confirmed.

We have a couple of viable options:

1. Start producing a practice load utilizing 41.3 grains of Accurate 2700 but we will also fine tune the load as a parallel activity. Since Accurate 2700 is more temperature sensitive than H4350 or Varget, it would be good practice to periodically verify the optimal load in very cold and very hot conditions. So in addition to cranking out practice ammo, we’ll periodically create some loads above and below 41.3 grains and chronograph them. Based on our results, we can adjust the average charge weight of our practice ammo.
2. Since this is a short range practice load, go with the 40.5 grain load. This will also have the benefit of less barrel wear. We’ll take the same steps to fine tune the load as described in the paragraph above.

Decisions…decisions…

So as our audience can appreciate, load development does not have be be a rigid linear activity. For those of you with a software development background, we’re taking more of an Agile versus a Waterfall approach. We’ll keep you updated as we further refine our practice load in subsequent iterations. As always, feedback from our audience is welcome and encouraged.

Here you can find our detailed load data: Load Analysis 123 Scenar Accurate 2700

Update (18 September 2015)

Here are some 100 yard groups and dot drills with the practice ammo Ed produced using the Dillon powder measure and 40.5 grains Accurate 2700 (Ed shot the two groups and then went across all five dots as part of a dot drill). Ed chronographed 10 rounds and got an SD of 11. Overall nothing worth writing home about but accurate enough for practice.

Ed can produce about 200 rounds in 30 minutes with the Dillon when using the integrated powder measure. When producing match ammo with H4350 he’ll still use the Dillon but he’ll dispense powder with theRCBS Chargemaster.