OCW gurus, Help Needed...

[heavies]

Been trying to wrap my head around this method for load workup. I am limited to a 100 yard range for development, and this seems like the method that will work best at this range. So, can anyone tell me if I am doing this right??

Components I used were:

Rifle is a Savage target action, Mcgowen 1:8 barrel 24" chambered in 6mmbr.

6mmbr Norma Lapua brass (not sorted), Body sized, necked sized with Lee collet die (6ppc) light interference of .001-.0015, 5th firing

Berger 105 grain VLD, HBN coated(not sorted), and placed .005 Into the lands past jam, as determined by softseating a dummy round into the lands.

Wolf small rifle magnum primer

30.2 RL-15 load is a control group (5 rounds)

Here is what I came up with...

Can someone give me an idea of what I am looking for.. Confused

I am thinking that 28.8 is near the center of one node, and 29.7 is near the center of another. Question,

If 29.3 is the 'scatter node' 29.7 should be close?

The 30 grain load gave me a slightly sticky bolt lift, but no primer flattening or ejector swipe, but I think this is very near max load.

What are your thoughts????

 

[Tripwire]

Re: OCW gurus, Help Needed...

Good counter clockwise rotation....

Hard to pick a good node out at 100 yards, I prefer 200.

Were it me in your situation I would look hard at the 29.5ish grain range.

Shoot another set with 29.4, 29.6, and 29.8 grains.

If they all impact in the same location then run with the middle charge and play with seating depth to close the groups up.....

 

[SPAK]

Re: OCW gurus, Help Needed...

Why the alternating .2 and .3 gr intervals?? Based on those targets alone I would be looking between 29.5-29.7. I've never shot berger vld's before, but usually when I run an "OCW" test I start .02" off the lands to find the charge weight and then I run a test on seating depth in .005" increments. But that's just me.

Your sticky bolt at 30gr might not be sticky .02" off the lands.

 

[heavies]

Re: OCW gurus, Help Needed...

Thanks for the replies.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Shoot another set with 29.4, 29.6, and 29.8 grains.
</div></div>

Looks like and area of interest. I will work on it there.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Why the alternating .2 and .3 gr intervals?? Based on those targets alone I would be looking between 29.5-29.7. I've never shot berger vld's before, but usually when I run an "OCW" test I start .02" off the lands to find the charge weight and then I run a test on seating depth in .005" increments. But that's just me.</div></div>

First time for me using VLD's, so, doing research on where to start with these pills, consensus was to soft seat them and work in one direction thereafter.

On the .2-.3 grains. Not much data on 8208XBR for these components yet so I wanted to find where the max would be, while at the same time look for a OCW.

Does my interpretation of the shot groups sound correct? Using Dan's OCW method from his website (http://optimalchargeweight.embarqspace.com/) it is kinda hard, for me, to get the exact method to finding the right spot. I have been studying various targets from other places and trying to see the pattern.

 

[wnroscoe]

Re: OCW gurus, Help Needed...

The two 6BR's I've owned and most of the ones I've built have all shot the following load.

Lapua Brass
30.3 grains of Varget
CCI450
105 Berger VLD just touching the lands

Skip RL15, N140 and F205M primers

Also, once you get close move to 300 yards to pick the best load, fine tune it with seating depth.

Your not close yet, the 6BR will one hole when you get there.

 

[trilogymac]

Re: OCW gurus, Help Needed...

No OCW guru but if it were me, I would look at 28.9 +.2 and -.2 to confirm center of group consistency and then fool with seating depth.
But then I don't like running charge weights near max and you said you had sticky lift at 30.

Hope this helps.
Trilogymac

 

[heavies]

Re: OCW gurus, Help Needed...

What are you folks feelings on this powder?

 

[heavies]

Re: OCW gurus, Help Needed...

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">30.3 grains of Varget
CCI450
105 Berger VLD just touching the lands</div></div>

What neck tension are you using for these?

 

[Seawalker]

Re: OCW gurus, Help Needed...

Well Dan Newberry is the man on interpreting OCW so I might suggest you post it over there if you haven't already.

Here is what I see, you have a definite node with nearly the same POI at the 28.8-29. Then you have a dispursion node at 29.3 and appear to be close to the higher node at 30. I would want to try another set at 29.8-30, but that's just me. Your overpressure signs might be alleviated by backing off the lands. As I remember Dan didn't put overemphasis on seating to the lands and certainly not jammed.

 

[heavies]

Re: OCW gurus, Help Needed...

Yes, I have this posted there for a while. Just got a response from Dan himself. He also agrees with the nodes. I was just thinking the same thing about the jam as well. I will play with both areas, and see what comes out of it.
Thanks for all the replies.

 

[clmayfield]

Re: OCW gurus, Help Needed...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Seawalker</div><div class="ubbcode-body">
Here is what I see, you have a definite node with nearly the same POI at the 28.8-29.
</div></div>

I agree. I wouldn't be blinded by the idea that you need to beat the acoustical shock wave out of the muzzle. You are showing two scatter groups at 29.3 and 29.7 gr. 29.5 looks nice, but you hate to park between those two charges unless you think you pulled a shot on one of them. If you look at the elevation change between 30.0 and 30.2 gr, you would probably want to stay away from these charges, which leads me to believe that your magic number is around 28.8. I especially like the minimum change in elevation in this range.

 

[Seawalker]

Re: OCW gurus, Help Needed...

If the accuracy of your lower node remains good when you back off the lands, that will be great, but it might be wise to shoot the whole sequence again seated off the lands and see what happens.

What is the listed max for this load with 8208 and how close are you to it with 30g?

Remember that while Berger VLD's were once thought to only shoot well when jammed, Berger has since found that some rifles will shoot best with vld's well off the lands. In fact I think they recommend trying significant jumps like .040, .080, and even .120 to find that sweet spot that may be .030 to .040 wide.

 

[Casey Simpson]

Re: OCW gurus, Help Needed...

28.7 to 29.2 but try Varget.

 

[brand692]

Re: OCW gurus, Help Needed...

I agree with both Casey and Seawalker.

When I shot the VLDs they had to be jumped. I jammed them for a while, but when Berger put out that memo about jumping them, and jumping them quite a ways, I gave it a whirl.

I used Varget. My node was at 30.1, if I remember right. Chamber was a 6BR Norma, no turn, .104 FB. Lapua brass with CCI BR primers. I jumped them .085 and thats where they shot the best.

Generally speaking, the VLD was a finicky projectile regarding seating depths. In the end, I abandoned them all together.

 

[heavies]

Re: OCW gurus, Help Needed...

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">What is the listed max for this load with 8208 and how close are you to it with 30g?
</div></div>

I am well above book max with this. If you try these work-up.

Hodgdon load data show 6mmbr Remington IMR 8208 XBR max @ 26.7 with 107 SMK, this is a fairly new powder and not much testing has been done with it. Much research led me to the loads I have tried. Some folks got much Higher than I. I have to try backing off the lands and see if pressures and accuracy become acceptable for the higher node, if not the lower area is totally fine, if accuracy is consistent.

I need to bust out my chrono, it's kind of a POS, but it'll give me a better idea of what these areas look like speed wise.

 

[Seawalker]

Re: OCW gurus, Help Needed...

I sort of figured you were well above the listed max. 8208 so far seems at least in the smaller calibers to need to go well above listed max to get anywhere near the velocity Hodgdon shows at max load. The chrono should give you a much better idea on how close you really are to where you want to be velocity wise.

Hope it works out for you. Really be interested in where you end up, so let us know when you finalize your OCW.

 

[okiefired]

Re: OCW gurus, Help Needed...

Like the others, I think you read your test well. I'd retest the 28.8 playing with seating depths if your crony says velosity is acceptable. I still dont understand why you alternated between .2 and .3 grain intervals though, I would keep that consistant next time. Good luck.

okie