Data Collection

[kottke_35]

Jim,

I think you are confusing yourself. Round Robin with two loads say, shoot A load at target 1, shoot B load at target 2, shoot A load at target 1, B load at target 2 repeating until you have 5 shots all the same load on the same target.

Obviously the more loads you have the more targets you need, the more time required.

B.

[Hoot]

OK, understand that you are dealing with an (or another?) engineer here. If I have one reloaded cartridge, say an FTX 250 with the powder, primer, etc., all the same, then I understand that I would shoot one round on each of the four targets in sequence, then repeat until I have 5 rounds on each target. That seems clear.

If I have reloaded two rounds, say an FTX 225 and an FTX 250, everything else is the same, then would I shoot one of the 250's on target #1, then one of the 225's on #2, 250 on #3, 225 on #4, then repeat until I have five rounds on each target? Each target would have the same rounds shot at it - 250's on #'s 1 and 3; 225's on #'s 2 and 4. Is that correct?

What if I have an odd number or different rounds, say 250's and 225's with different crimps? If I do a round robin, I could end up with mixed rounds on the same target - #1 could have a couple of 250's with a taper crimp, a 225 with a roll crimp (this is just an example), a 225 with a taper crimp and a 250 with a roll crimp, #2 could have different mix, etc. Or do I want to keep all of the same loads on each target, but just shoot them in sequence?

This could be a dumb question .

Not at all. It's one of those techniques that jumps out at you when graphically demonstrated, but it's not easily conveyed in text. Or, I suck at conveying it. It's like writing in text how to use an Abacus, versus watching someone use it while they're explaining what's going on.

It appears Brian replied while I was writing War and Peace so some of this will be redundant.

If you're shooting the same everything loads, there is little benefit from round robin. Dump them all in the same target unless you really want to know where each shot hit and you start chewing up the impact zone. Then spread them across several targets to maintain visibility.

OK, So I have four 5-shot loads to test that I wish to compare the groups for best results. I do not have to use a 4-up target, it just reduces the amount of movement of the rifle between shots, because each shot is going into a different target.

Lets say I want to test the new C.O.P. 160gr hollow points I bought (actually in process). I load five cartridges in four different powder charges. 45.5, 46, 46.5 and 47gr of Lil Gun. That's 20 cartridges total. When it comes time to shoot them, I take one representative from each charge weight and load them into my magazine in either ascending or descending order. Doesn't matter as long as you keep track of which load gets shot into which target. OK, so now my magazine has four cartridges in it, loaded lightest to heaviest from the top down. First shot out of the barrel will be the 45.5 into target 1. I do not shoot all five 45.5gr loads in sequence, into target 1. The next shot, I move my aim to target 2 and the next cartridge to pop up is 46gr. That goes into target 2. I move my aim to target 3 and shoot the 46.5gr, then target 4 to shoot the 47gr and my mag is empty. I load four more different charge weights in the same sequence of lightest to heaviest from the top down and shoot volley #2. 45.5 into target 1, 46 into target 2, 46.5 into target 3 and 47 into target 4. My magazine is again empty. Reload the exact same way aim and shoot in the exact same way until cartridge number 20 is shot, the mag is empty and each of the four targets has five shots from one charge in them.
The shot sequence would be:
Volley 1
45.5 into Target 1
46 into target 2
46.5 into target 3
47 into target 4
Empty Mag

Volley 2
45.5 into Target 1
46 into target 2
46.5 into target 3
47 into target 4
Empty Mag

Volley 3
45.5 into Target 1
46 into target 2
46.5 into target 3
47 into target 4
Empty Mag

etc.

If I had my rifle totally locked in a shooting vise and waited for the barrel to cool to the same temperature every shot, left every cartridge in the chamber the same amount of time before shooting, on a windless day, this would not be necessary as the main points of variability for the most part would have been eliminated. I would have great results and a totally boring outing. Labs that test loads are not doing so for the entertainment content, so boring does not matter.

Does that clarify things?

Hoot

[Hoot]

To add further dolor of paperwork to the process.

I use the same targets with 1/2 inch grid background when I shoot. After each shot, I write the velocity read from my chrony in my range book sitting next to the rifle. Alongside that reading, I score the shot as viewed through my scope. I use an AZ/EL quadrant system.
For Example:
Shot 1: 2285 -0.5 +1 (left high of bull)
Shot 2: 2239 +.75 +1.25 (right high of bull)
Shot 3: 2169 -1 -1.5 (left low of bull)
Shot 4: 2199 +.5 -.75 (right low of bull)
etc

Again, it helps me slow down and let the barrel cool. I may identify a POI characteristic related to velocity. Most importantly though is that anyone watching thinks I know what the heck I'm doing.

I may write notable observations as well like degree of sooting, pressure signs, smiley face, frowney face, etc.

As I mentioned before, I have brass push punch that I changed out the spring on to a lighter one. After I examine the ejected case, I punch a micro-dot in the extractor groove. That is how I track how many times a case has been fired. Just count the dots. I could do that after they come out of the tumbler, or as I resize them. This again gives me something to do while the barrel cools. My barrel temp gauge is my grasp. If I grab it and it feels temperature neutral to my skin temp, I can shoot again. These are not techniques one uses during recreational shooting as they distract your from the fun of the experience. It all about what gets your jollies.

Hoot

[kottke_35]

So John explained it a little better than I was able to. I was half asleep this morning when I got off work and was ready for bed, replying from my cell phone tobout!

Do you have a better idea of how it works now Jim?

B.

[Jim in Houston]

Yes, thanks to John and Hoot for clarifying things. Now to go shoot some robins.

[Hoot]

Yes, thanks to John and Hoot for clarifying things. Now to go shoot some robins.

Make sure you don't shoot the oblong kind. Strictly round.

Hoot

[Jim in Houston]

Uh Oh!!! Just discovered if you are shooting round robins, don't miss. They get PO'd.

[Hoot]

Uh Oh!!! Just discovered if you are shooting round robins, don't miss. They get PO'd.

In the spirit of sharing, I give you:

robin_4up_part.JPG (126.79 KiB) Viewed 8546 times

[kottke_35]

B.

[commander faschisto]

Hoot...you have GOT to find a way to print some of those up and put them on the marketplace forum here...