.308 OCW

[SavageSlayer]

Hey guys,

I would appreciate any help or insight on this OCW I just did. Round robin method letting barrel cool at least 1.5 to 2 min. in between shots.

It appears that groups 3 and 4 have roughly the same POI. It is hard to ignore group 2 though .204".

 

[CK_32]

Re: .308 OCW

Do a ladder test first. Save you a ton of time..

 

[vman]

Re: .308 OCW

I shoot 46.3gr Varget using Scenar 155's, kissing the lands... in lapua brass

I would say from the look of things you would get similar results.

Indoor range ey... whats max range?

Have access to more range like 300 yards? If you do, retry the OCW or just confirm those "good" loads u have out further and they will start to look different.

Or you could run a ladder also.

Nice shooting

 

[kyreloader]

Re: .308 OCW

The scatter node looks to be at 45.8g. It has 1 bullet hole at old impact area (bull) and 2 holes pointing to the next node. If that is your scatter node, the true OCW load will be 1.5% higher than that. That would make the OCW load 46.4 or 46.5g.

If you look at the target, the POI of the 46.2 and the 46.6g load is very similar, verifying the OCW.

I would load up at 46.2, 46.4, and 46.6g and see if all have similar POI. If so, pick the middle of the load range and work on overall length.

46.4 or 46.5 would be where I would look.

 

[Bloody_Tailgate]

Re: .308 OCW

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kyreloader</div><div class="ubbcode-body">The scatter node looks to be at 45.8g. It has 1 bullet hole at old impact area (bull) and 2 holes pointing to the next node. If that is your scatter node, the true OCW load will be 1.5% higher than that. That would make the OCW load 46.4 or 46.5g.

If you look at the target, the POI of the 46.2 and the 46.6g load is very similar, verifying the OCW.

I would load up at 46.2, 46.4, and 46.6g and see if all have similar POI. If so, pick the middle of the load range and work on overall length.

46.4 or 46.5 would be where I would look. </div></div>

How about 45.4 where they're all in the same hole?...just saying.

 

[BCP]

Re: .308 OCW

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Bloody_Tailgate</div><div class="ubbcode-body">
How about 45.4 where they're all in the same hole?...just saying.

</div></div>

Load some around 45.5 and some around 46.5 and see what happens. It all depends on whether you are loading for accuracy or for long range (ie, velocity).

Small 3 shot groups like that can oftentimes be flukes, all the stars aligned when you shot that group whatever.

 

[doc76251]

Re: .308 OCW

45.0 +/- 0.5gr

Don't push against the stock w/ your cheek so hard and things will become evident.

Cheers,

Doc

 

[223Rem]

Re: .308 OCW

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Bloody_Tailgate</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kyreloader</div><div class="ubbcode-body">The scatter node looks to be at 45.8g. It has 1 bullet hole at old impact area (bull) and 2 holes pointing to the next node. If that is your scatter node, the true OCW load will be 1.5% higher than that. That would make the OCW load 46.4 or 46.5g.

If you look at the target, the POI of the 46.2 and the 46.6g load is very similar, verifying the OCW.

I would load up at 46.2, 46.4, and 46.6g and see if all have similar POI. If so, pick the middle of the load range and work on overall length.

46.4 or 46.5 would be where I would look. </div></div>

How about 45.4 where they're all in the same hole?...just saying.

</div></div>

And don't look back......

I would load up 10 at the same specs as Group #2 and shoot a ten shot group. If you are printing .5 moa or less (excluding a called flyer)where else is there to go?

 

[kyreloader]

Re: .308 OCW

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Bloody_Tailgate</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kyreloader</div><div class="ubbcode-body">The scatter node looks to be at 45.8g. It has 1 bullet hole at old impact area (bull) and 2 holes pointing to the next node. If that is your scatter node, the true OCW load will be 1.5% higher than that. That would make the OCW load 46.4 or 46.5g.

If you look at the target, the POI of the 46.2 and the 46.6g load is very similar, verifying the OCW.

I would load up at 46.2, 46.4, and 46.6g and see if all have similar POI. If so, pick the middle of the load range and work on overall length.

46.4 or 46.5 would be where I would look. </div></div>

How about 45.4 where they're all in the same hole?...just saying.

</div></div>

If you do the same math with the 1.5% above/below the scatter node, the low node should be around 45.1g. You could load up around that node also and compare the high and low nodes. You may be coming out of the node at 45.4g, so shoot around it to see.

 

[SavageSlayer]

Re: .308 OCW

Thanks for all the info guys. I think will do some more development with smaller increments and move to 200 yards and see what happens.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BCP</div><div class="ubbcode-body">
Small 3 shot groups like that can oftentimes be flukes, all the stars aligned when you shot that group whatever. </div></div>

I definitely know that some groups can be flukes, but I shot this using the round robin method. Wouldn't that eliminate the "flukes"?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: doc76251</div><div class="ubbcode-body">45.0 +/- 0.5gr

Don't push against the stock w/ your cheek so hard and things will become evident.

Cheers,

Doc </div></div>

Doc,

Just curious how you can tell I was pushing too hard with my cheek? This interests me very much as I was paying close attention to my check weld as well as breathing and trigger pull.

 

[xdeano]

Re: .308 OCW

I load the exact powder charge as your group #2. It's a hammer. I found the charge using the ladder test, but from what i'm seeing i'd give #2 a shot at longer ranges, say 300 yards to see what it's doing. Then push it to 1K and see what you're getting.

looks good,
xdeano

 

[Shakeber]

Re: .308 OCW

Great discussion. I am currently prepping for my own OCW test on my Rem 700 5r in 308 and have decided to use RL15 under 165 Sierra Gameking (hunting). I have loaded 3 each @42.2, 42.5, 42.8, 43.1, 43.4, 43.7, 44.0 (my detemined max.), and 44.3. all loaded in Hornady Match brass with a coal of 2.75. Sorry to break into this thread but here is my question. In reading about OCW, I came accross OBT and tried to decifer that info. It is some deep *&%$, but very interesting. Can all this info be boiled down to muzzle velocity? seems that the velocity will establish for what duration the bullet is in the barrel and the exit time. Am I looking at this too simplistically? I will still perform the OCW but should I be looking at a chrono results? Thanks for this site and for all the helpful discussion.

 

[MALLARD]

Re: .308 OCW

i think your ocw results were inconclusive

, i would re-do the test again , probably not round robin , i havnt heard of peoople doing that for OCW test , is that common ?

i know people test round robin with ladder,

if you OCW test i would test 5-7 rounds per weight. Or a ladder test.

maybe you should test .3 increments instead of .4

 

[kyreloader]

Re: .308 OCW

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MALLARD</div><div class="ubbcode-body">i think your ocw results were inconclusive

, i would re-do the test again , probably not round robin , i havnt heard of peoople doing that for OCW test , is that common ?

i know people test round robin with ladder,

if you OCW test i would test 5-7 rounds per weight. Or a ladder test.

maybe you should test .3 increments instead of .4 </div></div>

OCW tests should always be done round robin to equalize the environmental effects(wind, barrel temp, lighting, etc.).

http://optimalchargeweight.embarqspace.com/

 

[MALLARD]

Re: .308 OCW

thanks ky
i agree about minimizing environmental factors but i would think shooting rounds at different charge weights , round robin, would affect harmonics? or no?

 

[clmayfield]

Re: .308 OCW

From Dan Newbury's site: "Remember, don't get "bowled over" by a tiny group which falls out of the OCW zone."

I put your target on On Target and measured the vertical of all the groups, and it looks like your OCW is between 45.8 and 46.2. Remember, you are mainly trying to find 3 consecutive groups with the closest POI. That is the 46.2 gr load. The POI of the 45.8 gr group is very close to the POI of the 46.2 gr load, so I would go between there.

Truthfully, the 45.4 gr load is not that bad in terms of dispersion from the 45.0 gr and 45.8 gr, but there is a better node with a higher charge weight that presumably isn't giving you any pressure signs, so I like 46 gr or so.

The problem in interpretation of the OCW is that a lot of people see the tight group and want to go right there. The truth is OCW is more like a ladder test than testing by groups.

What you could do is load up 10 rounds of 46 gr and 10 rounds of 45.4 gr and fire 4 5 shot groups as a tie breaker.

 

[KeeblerArmy]

Re: .308 OCW



<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: doc76251</div><div class="ubbcode-body">45.0 +/- 0.5gr

Don't push against the stock w/ your cheek so hard and things will become evident.

Cheers,

Doc </div></div>

I second that question. What does pressing your cheek too hard too and how did you spot that?

Doc,

Just curious how you can tell I was pushing too hard with my cheek? This interests me very much as I was paying close attention to my check weld as well as breathing and trigger pull. [/quote]

 

[doc76251]

Re: .308 OCW

In an effort at brevity since I have noticed I get long winded on occasion

Let's look at what we "know" about the shooter.

The groups were fired indoors which "should" obviate any horizontal dispersion of the groupings.

The shooter has repeated "doubles" which means he can drive the rifle pretty good.

The errant shots are random in location and direction which tells me inconclusively that it is not the rifle. Having the notes from that days shooting would be defining. Add in the "doubles" and it leans heavily towards a good rifle.


The powder primer and boolet combo are all in or near generally accepted OCW's for various platforms, so he's looking in the right places.

The shooter keeps track of stuff and pays attention to details as evidenced by the info posted w/ the groups. The last part is telling because he said that he took 1 - 2 minutes between shots which also tells me that he got off the gun between shots.

Given all of the above and 20 years of watching people (myself included) do this leads me to believe that while "paying attention to my cheek weld" that he was pressing and letting off his face position to get the same cheek weld. In the process he was also probably increasing and decreasing his firing hand grip pressure to get everything "right". Add the distance between target locations on the paper and it makes sense that he was muscling the gun slightly and intermittently during the strings. Without the notes to confirm it I would also hazard a guess that the "thrown shots" were not all the last shots of the group, or all the first or all the second.

Of course as soon as I hit "post" someone will say "OK, Doc figure this out." as a test. The OP was not testing, he was shooting to the center as best he could and as such there was no intent.

As so many have said before me, a relaxed shooting position is repeatable, add muscle tension and things get funky.

Cheers,

Doc