Standard deviation and groups size/pattern.

[DenisA]

Hi Brad, doing that, how do you identify horizontal spread in a load and then even head wind, tail wind, boils and wind ramping up the face of shooting mounds will all effect vert.

I believe that 100m is the best 'control' that we can get for load testing. We just have to be articulate about inturpretting the targets and results.

That said there are plenty of better shooters than myself, most likely you being one of them, that develop at the longs. I'm not telling any one anything.

[johnk]

I believe that 100m is the best 'control' that we can get for load testing. We just have to be articulate about inturpretting the targets and results.

That's not entirely correct.

The problem faced is that beneficial coincidence that is experienced, apparently due to the dynamics of the rifle (I'm not game to say harmonics), can & coincide into an acceptable group with shots of substantially different velocities. Short range benchresters use this phenomenon effectively essentially as a final test because they tailor a load for a single distance (and for one time on a single day), but because we expect a load to work for us over a number of distances, 100 yard grouping is irrelevant unless supported by other data that suggests that vertical stringing will not occur as distance increases, specifically, a useful velocity spread.

The more experienced among us might be comfortable that the loads that they tailor are intrinsically within suitable velocity bands, but for the rest of us, confirmation is useful. The way we can achieve this is either to verify our loads at a range of distances, or as I see it, test with the support of a chronograph.

John

[Brad Y]

Denis

When I started on my 260 improved, I didnt have access to a chrony. Or a reliable one anyway. So I thought it would be best to let the target tell me what the gun liked. Starting with 140 hybrids jumped 15 thou I loaded a big ladder test. Starting at 42.5gr and up in 0.3gr increments through to 44.5gr. At 900m we were lucky enough to have a fairly good day, yes enough wind that scoring a possible was tricky, but good enough to get an idea. There were no head or tail winds put it that way. I laid down and put a couple of sighters down to get as close to zero as possible on the ET. Then shot 5 in quick succession aiming at the same point (no holdoff for wind). Wrote the measurement of the vertical placing of each shot from the waterline of the target. I then continued each one. 43.1-43.7 showed to be fairly flat. I did the same test again at 500m and 700m and found 43.7 to be about right. I backed it off 0.1gr and shot 43.6gr and 15 thou jump for ages. The main thing was that I knew it would hold decent vertical at long range. It turns out I probably could have worked on the horizontal a bit more, which I did after getting access to a magnetospeed. But the load I changed to I did come across out prior to using the magnetospeed. It was just a combination of laziness and not wanting to jam bullets. My X count has improved now and vertical is still as good as it was before.

I will do a similar 300m replicated ladder with the magnetospeed in my shehane when its built. But will also use my findings there out at 900m to confirm. Numbers are great and I have learnt the value of using a magnetospeed but targets do have the final say in my mind.

There was another shooter in WA who went into the queens with an ES of 8 and SD of 3 from memory and had vertical problems the whole way through.

[IanP]

Hi Brad, doing that, how do you identify horizontal spread in a load and then even head wind, tail wind, boils and wind ramping up the face of shooting mounds will all effect vert.

I believe that 100m is the best 'control' that we can get for load testing. We just have to be articulate about inturpretting the targets and results.

That said there are plenty of better shooters than myself, most likely you being one of them, that develop at the longs. I'm not telling any one anything.

Your not alone in your opinion that 100m/yd is the best control, (environmental conditions) for load testing, etc. If you buy the Bryan Litz DVD set "Putting Rounds ON Target" he emphasizes this very point. He then goes on to test at ranges all the way out to 1760yds to prove the accuracy of ballistic programs based on data gained at 100m/yds. I think you would find reassurance that your on the right track if you get a chance to watch the DVDs!

There are a number of things that cause vertical including wind changing direction from left to right or vise versa. I have a spreadsheet that can calculate this very thing all based on Litz's formulas. A spreadsheet was of no help to me recently when I found inconsistent recoil management can also cause vertical.

This is what makes our sport both interesting and challenging, that so many things contribute to high scores. So many shooters follow different paths to arrive at the same objective.

Ian

[Quick]

I'm the shooter who went into the queens with those low numbers. Numbers seemed awesome but, rifle just didn't group and had vertical. And I know it was vertical when another FO shooter who shot at the same time as me throughout the duke and queens was shooting bugholes all week. Ask him what his SD and ES is. I just got the vertical and was pulling my hair out until I sat down with a mate and analysed the groups and scores and compared them in same conditions.

I have since changed powder and after what my rifle did yesterday with it, it's doing what a good open rig should do. I got a very good score in very bad conditions. Just gotta tweak it now.

I remember asking to a 1000yd BR shooter a few years ago on a different forum, he said to me that he have up using a Chrony a while ago and does his load testing at the ranges he shoots at.

I'm not saying that ES and SD is wrong, but it told me a one thing and the opposite happened. Just my experience with it so far.

[Matt P]

Quick
Low ES and SD and small groups don't always go together, I actually work the other way, I find a load that shoots small groups then check what the ES is, I don't take much notice of SD, as IMO normally the number of shots we like to put through our barrels is too small to give a accurate number.

Matt P

[Quick]

Matt,

That's what I do now. Once I have found a load, I'll check it on the Chrony but won't tweak it to get numbers down if it harms accuracy. As brad said and I have to agree, the target speaks the truth and is what matters. Chronying don't win matches.

The load in question shot well in testing at 900m a fortnight before the queens, but that was in a certain weather condition. The duke and queens was completely different and she didn't wanna play. When I shot the low Chrony numbers I also shot a 5 shot group at 900m that would have fit into XRing. But it just didn't repeat that accuracy so I think it was a powder/bullet issue aswell.

All I know is what I did yesterday at 900yds and the rifle shot very well in bad conditions with the new powder.

[IanP]

Quick, I have also found that temperature makes a measurable difference as well. I'm currently using a 300WM with 230gr bullets and 72 to 76gr of powder and now use a lower end powder load to cater for the temperature effects. Temperature effects have really been noticed in this large capacity case using AR2225.

The idea I'm pursuing is that this rifle has a very large accuracy node and instead of loading to the high end of the node, (my previous practice) I now load at the low end. When the temp and pressure increase I'm still on the accuracy node. Thats my plan and I will see how it pans out over the summer period.

I wonder if your variation at the Queen's & Duke's was caused by temperature change?

Ian

[Quick]

Ian,

It could have been. We think that it's a factor. I worked the load up and did the verification in warm conditions and the queens and duke did not get as hot as that testing day so that could have been it. I didn't think the powder in question was temp sensitive but in a hot 6mm, It could be. My own testing with 308 when I have done some powder burn rate tests is that it matters more on the load I think aswell. But I need to do the same for my 6mm.

[DenisA]

Quick and Matt, thanks, that's exactly the real world experience from others that I wanted to hear.

I guess I just needed to settle in my mind that barrel harmonics and MV consistency are 2 separate characteristics that work independently of each other.

[Quick]

Denis,

All I know is that Im just going to let the target tell me what the rifle likes and go from there. Easier and I wont chase my tail that way.

[DenisA]

I understand your point quick, but I think its important to understand and consider different theories, and why people swear by them, whether we agree with them or not.
There are so many controversial topics in this industry.

The best decisions are those based on a broader understanding.

That's why forums such as this are such a valuable tool. They allow discussion with people that you would never otherwise get to meet based on specific experiences that we may never otherwise get to see.

[Quick]

Denis,

I understand. I know there are many ways to conduct load dev. I just know what works for me.

[AlanF]

...I guess I just needed to settle in my mind that barrel harmonics and MV consistency are 2 separate characteristics that work independently of each other.

Denis,

That's my understanding - and theoretically, you can actually reduce your long range vertical by perfecting either of them. If you get good elevation on a target at the longs it's best to know why. If you have excellent velocity consistency, then you haven't necessarily found a sweet spot for your barrel, whereas if you have good elevation despite velocity being a bit up and down, then that implies that your tune is good.

Alan

[Quick]

I know of one 6mm barrel that shoots extremely well and had very flat vertical at all ranges but it's ES and SD numbers are poor. It's weird how that works out but it does. Barrels are finicky things for sure.