Long range load development at 100 yards.

[Erik Cortina]

Gilream, try 25.6 and work on seating depth.

 

[6BRinNZ]

6BR, yes, that's the idea.

Ok - I am short on bullets - I might just dial in the tuner and come back to a seating depth test when more arrive, .308 so throat erosion isn't going to be significant so I should be ok with this seating depth for a while. Or are there pitfalls with this approach that you would recommend finding seating depth window ahead of tuner setting...i.e. the tuner setting would wait until bullets arrive, which could be as much as a 1/3 into the season.

PS - thanks heaps for your advice and this thread - its been the single most beneficial thread that I have seen out there.

 

[Erik Cortina]

Just adjust tuner for now. You'll be fine.

You're welcome.

 

[6BRinNZ]

Just adjust tuner for now. You'll be fine.

You're welcome.

Thought I would post my tuner groups. This new load was harder to dial in than the original load. It is incredibly interesting and so fast all up though.

I have just posted the pictures of relevant groups to look at - other groups were tightish but not good enough to bother with.

I got to settings 10 and 12 and thought it could be worth going back and looking at 11...I might do this some other time.

I figured I needed to make some stronger changes so moved to 15 and then 20 - bingo, I then moved to 25 (equivalent to 1 full revolution) and then back to 20. I have left it on 20 for now. 20 looks to be very repeatable.

I noticed that while the two groups on setting 20 were tight the POI moved but I am guessing this is due to the way I tightend the grub screws or maybe I don't have it in precisely the same place?

When bullets arrive I have seating depth to play with and to look at tuner settings between 20 - 25?

 

[Erik Cortina]

Looks like setting #20 is it.

 

[6BRinNZ]

Looks like setting #20 is it.

ta - I am stoked I bought the ectuner

 

[BradY]

Wayne

Have you been able to shoot with the tuner on 20 at 100yds then take it further back to 500+yards yet? Has it stayed tight or do you need to adjust it for the longer range? After a rechamber Im now back to 56.8 powder with a 180vld in my shehane jammed 10 thou and 57.0 with the same bullet jumped 40 thou. Both loads shot well at 700m today but I havent had the chance to adjust the tuner yet to see if any will shrink down, nor have I been able to get an ES or any idea of velocity.

 

[Steve Blair]

You will not need to adjust the tuner for various distances. It is important to note that a tuner is not a panacea. Orderly load development resulting in low ES, broad charge window, and seating depth set correctly is still necessary. If all that is in order, correct tuner setting will reduce dispersion further and slightly broaden the node by aligning barrel harmonics to coincide with the center of the charge window. This approach and Erik's tuner has made my .300 WSM a very dependable and forgiving rifle through several barrels.

 

[6BRinNZ]

Wayne

Have you been able to shoot with the tuner on 20 at 100yds then take it further back to 500+yards yet? Has it stayed tight or do you need to adjust it for the longer range? After a rechamber Im now back to 56.8 powder with a 180vld in my shehane jammed 10 thou and 57.0 with the same bullet jumped 40 thou. Both loads shot well at 700m today but I havent had the chance to adjust the tuner yet to see if any will shrink down, nor have I been able to get an ES or any idea of velocity.

Hey Brad,

My experience so far supports Steve's and Erik's views. Once set pretty much leave it alone.

I haven't used setting 20 past 100 as I have only just worked it up. I had used 44.1 and setting 8 from 300 - 1000 (the initial load selected). I had a tough time at 1000 but it turns out that load was marginal at 1k. I have cleaned 300, 500 and 600 multiple times and dropped 1 at 900. I had one good day where all the local clubs have a midrange shoot off and I never dropped a shot from 300 - 600 including sighters (it was the sighters that made it)...not bad for what was effectively a 40 shot load development.

I still have a lot to learn about the 308, even with things like annealing, I still don't have my benchsource timing quite right as my resizing was not as consistent as what I get on my 6br, and I'm not fully convinced I have quite the right amount of neck tension yet, I have a SEB rear bag coming which should help as well....all of this will come and I'm confident I can get this rig to truly hammer.

One valuable lesson I learned was with the magneto chronograph. Typically I use this on my club days so that I can compete and get chrony data under match conditions...you have to watch you don't move the tuner when strapping on the chrony...

Putting all of this into perspective If I get the initial load choices correct I can't see the need to worry about the tuner over distance.

 

[Erik Cortina]

6BR, don't be afraid to set the friction screws on the tuner pretty tight. You will still be able to turn it by hand.

 

[6BRinNZ]

6BR, don't be afraid to set the friction screws on the tuner pretty tight. You will still be able to turn it by hand.

yeah no probs I set them tight, its not an issue with the tuner - the v2 magnetos have spacers to fit the fat barrels, and its all a bit fiddly now, I'll figure it all out as the magneto is awesome for club shoots and getting data from your load while still competing (club days).

 

[Raythemanroe]

What if your long high bc bullet doesn't stabilize before 100y but performs well at a 1k mark? I believe that some bullets really don't show full potential until 300y. Would you still look for the same things at and use 100y mark and not worry about groups size?


Ray

 

[Erik Cortina]

What if your long high bc bullet doesn't stabilize before 100y but performs well at a 1k mark? I believe that some bullets really don't show full potential until 300y. Would you still look for the same things at and use 100y mark and not worry about groups size?


Ray

If you don't stabilize the bullet by the 100 yard mark you are giving up BC.
I have yet to see a bullet stabilize in 100 yards. Even the Berger 230's will stabilize in 100 yards.

 

[Alex Wheeler]

How wide of a tune are you guys getting with this method? Example, if you a shoot a 2" 5 shot group at 1k when your in tune, and load .3 on either side of that how much will the group change?

 

[Erik Cortina]

How wide of a tune are you guys getting with this method? Example, if you a shoot a 2" 5 shot group at 1k when your in tune, and load .3 on either side of that how much will the group change?

If a barrel shoots 2" groups at 1000 yards I use it as a tomato stake!

 

[Alex Wheeler]

How wide of a tune are you guys getting with this method? Example, if you a shoot a 2" 5 shot group at 1k when your in tune, and load .3 on either side of that how much will the group change?

If a barrel shoots 2" groups at 1000 yards I use it as a tomato stake!

Ya I bet you do You know what I mean, can you load a couple tenths either side and not see a change?

 

[Steve Blair]

My .300 WSM has a charge window ~.8 grains wide. Within that range, ES, velocity and accuracy do not change significantly. My Shehane is ~.5 grains. I load both to the center of their respective ranges and don't worry about the charge unless post match chrono sampling reveals a change.

 

[Erik Cortina]

How wide of a tune are you guys getting with this method? Example, if you a shoot a 2" 5 shot group at 1k when your in tune, and load .3 on either side of that how much will the group change?

If a barrel shoots 2" groups at 1000 yards I use it as a tomato stake!

Ya I bet you do You know what I mean, can you load a couple tenths either side and not see a change?

Same as Steve, I can load on each side of node with no decrease in accuracy. I also load to the center of the node. If I shoot in really hot conditions compared to the temperature at which the load was developed, I then load toward the bottom of the node, but never outside the node.

 

[BradY]

Thanks guys- I will be doing the close range load development this week hopefully. Even though I have done it slightly backwards with the first shots in this chamber at 700m, I got to see what worked well enough at that distance and know where a good area should be to work at.

 

[Texas Solo]

This method works!

Erik, I've been following this thread since post #1. Learned a ton, THANK YOU.
I finally got my 308 to where it makes sense to me. Using LC brass, my charge weights are way lower than most, but the results of this test were identical.
Using 168 Hornady and IMR 4064, I got a node of 38.5 > 39.5. It was so obvious that Stevie Wonder could see it.
I went with 38.7gr to leave some room for the South Texas heat.
I then played with the seating depth, and at -.020 I hit groups at .292" with an ES of 15. ;D

THANK YOU, THANK YOU, THANK YOU.

PS...I have another question for you that's off topic. O.K. to P.M. you???