Long range load development at 100 yards.

[savageshooter86]

Yep. Same result. I used it to get a precise center point for the group since it will calculate the middle of a group.

 

[Bowhunter4]

I found this target, and I think it's a perfect example of how some people might choose the wrong load because they fell in love with a group without reading the groups properly. This target was shot with my 6.5x47 Lapua and 139 gr. Lapua Scenars with VV N550 powder.

At plain sight, 38.5 gr. appears to be the best group, but if you look at the groups next to it they don't hit the target on the same place vertically in relation to the bull's eye. The load is not stable and this load would cause problems when moving further out because it is not inside the accuracy node.
However, loads 39.5, 40.0, and 40.5 are vertically in the same place in relation to the bull's eye. This is the accuracy node for powder charge, my next step would be to load 40.0 gr. and adjust seating depth and bring the group in and done, I now have a load that would shoot out to 1,000 yards. Also, when the groups line up vertically, the speed also varies very little over the chronograph for the loads that line up on target, it appears that the speed flat lines for a while before it starts to jump up again, this is where you want to be.

so are you saying that 38.5 is your low node ? and 40 is your high ?

 

[savageshooter86]

38.5 is not a node here. Look how it hits almost even with the horizontal line on the target. Then notice how the 38.0 hits lower than 38.5. And then look at 39.0 it hits higher than 38.5 and 38. So this is not a node

 

[Erik Cortina]

38.5 is not a node here. Look how it hits almost even with the horizontal line on the target. Then notice how the 38.0 hits lower than 38.5. And then look at 39.0 it hits higher than 38.5 and 38. So this is not a node

Correct, 38.5 is not a in the node.

 

[Erik Cortina]

I used OnTarget to plot the center of my groups and chose the 3 that hit closest POI vertically off my POA. Then chose the middle charge like you do. Then I played with seating depth to get the smallest group with the charge I selected. I trusted OnTarget to calculate it more precisely than my eyes could. Used the measuring and scale function in the program to get it accurate.

One thing to add is that I don't go with the three groups that hit the closest to POA, I pick the three that shoot the same place vertically based on POA, even if they are the farthest away from POA.

 

[savageshooter86]

I pick the three that shoot the same place vertically based on POA, even if they are the farthest away from POA.

Yep. I used Dan Newberry OCW method which is very similar to your way. Seems to work

 

[memilanuk]

Another +1 for OnTarget Precision Calculator for this... sometimes it can be hard to visually discern the true vertical center of the group using a Mk1 Mod0 eyeball - usually the biggest source of error in 'choosing' the right node, in my experience. Scanning/imaging the target and running it thru OnTarget to compare the actual vertical group center vs. point-of-aim can be very handy. Probably helps that I enjoy messing with things like this, so YMMV

 

[Nomad47]

Erik, I'm fairly sure you use QuickLoad. Do you also use Chris Long's OBT theory? If so, how did the 40 grain charge work out to one of Chris' nodes?

 

[Erik Cortina]

Erik, I'm fairly sure you use QuickLoad. Do you also use Chris Long's OBT theory? If so, how did the 40 grain charge work out to one of Chris' nodes?

Bill, I do use QL, but find that sometimes the OBT is a little off. This way ensures that the load window is correct.

 

[Alex Wheeler]

Eric, How big are those groups after you tune the seating depth, and how much vertical at 1k are they giving you? Have you ever had a gun that did not print like that? My groups tent to follow a sine wave pattern, usually the groups that print highest or lowest (when the barrel is at the end of it whip) will give the least vertical and best groups. I shoot a dasher and find my windows are small, if I load .2 either way the load will get vertical.
Thanks

 

[Erik Cortina]

Eric, How big are those groups after you tune the seating depth, and how much vertical at 1k are they giving you? Have you ever had a gun that did not print like that? My groups tent to follow a sine wave pattern, usually the groups that print highest or lowest (when the barrel is at the end of it whip) will give the least vertical and best groups. I shoot a dasher and find my windows are small, if I load .2 either way the load will get vertical.
Thanks

The groups get down in the .1's and .2's after seating depth tuning. That gives somewhere about 4" - 6" groups at 1,000 yards. During competition, I have shot 198's with this load at 1,000 yards.

 

[6BRinNZ]

Hey Eric - thanks for the info and the ongoing feed back...

Would it be possible to provide the other part of the puzzle and post the graph of the fps for the session?

If I understand correctly the vertical location plus the flattening of fps are the two key elements to be looked for.

 

[aj300mag]

Erik,

Did you rerun the 100 yard group with the three loads (39.5, 40.0 & 40.5) once you established the seating depth? Did you see any vertical/ horizontal stringing if you did?

 

[Erik Cortina]

Erik,

Did you rerun the 100 yard group with the three loads (39.5, 40.0 & 40.5) once you established the seating depth? Did you see any vertical/ horizontal stringing if you did?

aj, how is it going ol' buddy ol' pal!? ;D

No vertical stringing after tuning.

 

[Dgd6mm]

Erik,
Thank you for sharing your knowledge.

Don Dunlap

 

[Erik Cortina]

Erik,
Thank you for sharing your knowledge.

Don Dunlap

My pleasure!

 

[Trapper243]

I will double the thanks. That was a worthy read.

 

[tonysnoo]

I will double the thanks. That was a worthy read.

Ditto for me, thank you!

 

[sailhertoo]

You need to read the groups, not shots on the group.

Like I said, most people will go with 38.5 and they will be wrong.
Look at 38.0 and 39.0, the groups don't line up with 38.5 vertically.

Now, look at 39.5 - 40.5, the groups line up vertically on the target.

Yep, I understand now.

Thanks for sharing Erik, I hope to get to meet you one day at a shoot. I owe you a beer or a box of bullets at the least.

 

[M14AMU]

I prefer to test from 1000...such that the group 'lines up' in the center!


15 rounds from 1000 yds. with 6.5x47 Lapua by Sharps45 2 7/8, on Flickr