Accuracy Analysis

I’m going to start posting results of range sessions once or twice a month as we get our accuracy analysis up to speed. Right now the plan for a given weapon is 3 10-shot groups, so 30 shots total. Time between shots 30 to 60 seconds, 100 yards, mild conditions (hopefully), and the 3 10-shot groups will be taken with no scope adjustments so that they can be compiled into a single 30-shot group. Time between groups could be 5 to 30 minutes and is not deemed relevant, except that the barrel will have had a chance for substantial cool down.

The following image indicates what I hope to produce for these updates, which will be used to characterize a given barrel and weapon:


That 100 yard 10-shot group is just an example as I’m still working on presentation. The group was shot with one of our 18″ .223 Fulcrum barrels with 77gr Federal Gold Medal Match ammunition. In the future I plan to measure bullet velocity with with my LabRadar unit. The Sigma values  above indicate that this rifle and ammo combination is no worse than low Class 5, and probably Class 3. This is as much information as can be gleaned from 10 shots, which is one reason why 3-shot and 5-shot groups are dubious for gleaning weapon accuracy. I took 15 other shots with Hornady 75 grain match ammo and when both groups are centered and combined, just for example to get more shots in the group, I get the following retults:


In this case the Sigma value over a 95% confidence range tighten up from [.221, .433] to [.265, .397]. This indicates the rifle is no worse than Class 4, and could reasonably be Class 3 (especially given that I was the shooter and I’m not particularly good). Class 3 is realistically as good as auto-loading rifles get so this is the target, so to speak, for a competition gun like this one. For grins we can separate the two different groups and overlay to see how the different ammo shot:

I didn’t measure muzzle velocity of any of the shots, but that is planned for future analysis. In the future we can tag any given shot with a muzzle velocity and then analyze the results.

The important takeaway is that it takes a lot of shots to properly characterize weapon accuracy, and that even with a lot of shots, the accuracy potential of the weapon is hard to nail down with a lot of precision. Still, were confident that we can back up our Class 5 guarantee on our products, and that we’ll be able to zero-in on that number a lot better with more data.