3 accuracy nodes: Which one should I choose?

[Kevin1]

I’m noticing 3 accuracy nodes with every 2 grains of powder increment. The question is which one should I chose for my loads considering that I don’t shoot pass 500 yards.

Accuracy nodes:
First is at 41 g (not in the picture)
Second is at 43 g
Third is at 45 g


Distance: 300 yards
Lapua brass with 175 SMK and CCI n200 primer
Powder charge (Varget): From 42.5Gr to 46Gr.
Rifle: Savage 308 10FP in B&C Medalist


Below the two targets and the pics of the brasses (from left to right, 42.5 to 46 Gr)

Then I dialed down 2moa and shot the 2d target (44.5 to 46gr)

I don’t believe I have any signs of pressure.

 

[SIG700]

Re: 3 accuracy nodes: Which one should I choose?

Assuming 41, 43, and 45 are infact accuracy nodes (hard to tell from only two shots), and that you're staying from 500 and in, I'd stick with 41. Less powder, less pressure, longer case/barrel life. (And an extra few charges per pound). Also, a little difficult to tell but I believe I see some over pressure signs on some of your casings (<span style="text-decoration: line-through">extractor</span> *edit* ejector* marks), but I could be wrong. 45.5g and 46g are both over Hodgdon's max load for that particular set up.

 

[Hoverp]

Re: 3 accuracy nodes: Which one should I choose?

What he said..you really need more than 2 shots to see an accuracy node, dont shoot left to right , get a long piece of paper and shoot at the same target just with the increasing powder loads to see your node based on velocity, shoot a string of at least 3 then go mark the target, let the barrel cool, shoot the next higher powder charge , mark the target, reapeat.....all the while holding the same sight picture on the same target.then look for your node where most rounds are impacting the same relative position (measured vertically) and take a look at what powder charges that covers, then pick a nice round number in the midlle of the powder charges that produced the closest in vertical spread.

 

[20Incher]

Re: 3 accuracy nodes: Which one should I choose?

Nevermind read it wrong

 

[20Incher]

Re: 3 accuracy nodes: Which one should I choose?

Thanks Sig700 Do you shoot PA 1000?

 

[clmayfield]

Re: 3 accuracy nodes: Which one should I choose?

I definitely see ejector marks and maybe some extractor marks.

If you were to number from 1 to 16, going left to right on 2 rows, I see ejector marks on: 2, 3, 4, 6, 7, 9, 11, 13, 14, 16.

I already made one link to this today, might as well do it again:
http://riflemansjournal.blogspot.com/2011/02/cartridges-long-range-reloading-safety.html

 

[SIG700]

Re: 3 accuracy nodes: Which one should I choose?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 20incher</div><div class="ubbcode-body">Thanks Sig700 Do you shoot PA 1000? </div></div>

ha ya I figured I'd delete my comment since you fixed your mis-read. Na I've never been out to PA 1000. I shoot at New Holland (600yds for now- planning on expanding to 1k in 2014). By the way- your signature, f*cking hilarious.

 

[Kevin1]

Re: 3 accuracy nodes: Which one should I choose?

Yes this is a ladder test. I have confirmed the 2 first accuracy nodes (41 and 43g) with additional loads. But not enough and not at all distances.

My only concern with 41 g is that I'm not sure if it's optimized for the 308 case as it leaves a lot of empty space.


Is it possible that one accuracy nodes gives better result at 300 Y than at 100Y and the other be more suitable for 100 Y?

I guess I'll need to do another ladder testing at 300 y from 40g to 45.5 g with 3 bullets for each loads

As for the pressure signs, there is an extractor mark, but you can't feel it with your nail. It's only shiny. Could this be considered as pressure sign?

 

[Rthur]

Re: 3 accuracy nodes: Which one should I choose?

I was seeing the same thing Carter, there appears to be ejector swipes on several.

 

[SIG700]

Re: 3 accuracy nodes: Which one should I choose?

Ya even if its just shiny its still a sign of over pressure. Kinda looks like a few may have flatter primers. Here's a quick reference.

And like Hoverp said- ladder testes are usually done best with all loads shot at the same target (each marked with its load)

 

[Kevin1]

Re: 3 accuracy nodes: Which one should I choose?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: SIG700</div><div class="ubbcode-body">Ya even if its just shiny its still a sign of over pressure. Kinda looks like a few may have flatter primers. Here's a quick reference.

And like Hoverp said- ladder testes are usually done best with all loads shot at the same target (each marked with its load) </div></div>

The pics of the cases are from left to right 42.5 to 46 Gr. You can notice the shiny mark even on some of the rounds with just 42.5 Gr. Does this mean that I have to stick with the first accuracy node at 41g?

 

[Tripwire]

Re: 3 accuracy nodes: Which one should I choose?

Refer to my post on your FL "seizing" thread....sort of an appropriate Freudian slip I might add.

Read some books dude, seriously.

Things other than "pressure" that may cause the marks you have could be: over sizing and creating too much headspace; case lube left on the "brasses", oil left in the chamber.

MUCH is suspect here............