OCW test --- interpreting results

[Bob 964]

Bullet: Hornady Amax 178
Powder: Varget (43.0 gr. - 45.1 gr.)
Rifle: Savage 110FP .308 (1:10 twist)
Brass: Lapua
Primer: CCI

What do you see? Looks like a good node from 43.0 to 43.6, and a good node from 44.2 to 44.8. Am I correct in concluding that 44.5 (Load #6) would then be my optimal charge weight?

 

[oldfatguy]

Re: OCW test --- interpreting results

The bullet choice tells me you are loading for longer ranges so the 44.5 is looking good. Might want to reduce the steps around that weight to refine your results a bit.

OFG

 

[kenmack]

Re: OCW test --- interpreting results

Am I short on theory or are not 43.3, 43.9 and 45.1 the nodes, and if not over pressure, 45.1 is the desired OCW?

 

[vman]

Re: OCW test --- interpreting results

Notice how every jump up by 0.6 grains produces a nice group?

 

[Bob 964]

Re: OCW test --- interpreting results

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kenmack</div><div class="ubbcode-body">Am I short on theory or are not 43.3, 43.9 and 45.1 the nodes, and if not over pressure, 45.1 is the desired OCW? </div></div>

As I understand Dan Newberry's instructions, you measure group sizes and distances and directions from the bullseye to identify a string of 3 consecutive groups that come the closest to hitting the target in the same POI and then select the charge weight that represents the center of this string. That is why I think 44.5 is the OCW.

 

[oldfatguy]

Re: OCW test --- interpreting results

That is my understanding of Mr. Newberry's instructions as well. Tempting to go with the load that yields the tiny little group, but that is not the intent of the process.

Just for fun I will try to remember to load a few rounds with the smallest group and see if it repeats.

OFG

 

[Helter]

Re: OCW test --- interpreting results

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: oldfatguy</div><div class="ubbcode-body">Just for fun I will try to remember to load a few rounds with the smallest group and see if it repeats.

OFG </div></div>

A better test would be to load 1 -.1 gr, one at that load, and one +.1 gr and see how it behaves.

 

[jsthntn247]

Re: OCW test --- interpreting results

Save yourself some time and take the 3 tightest groups and shoot them again at 500+ yards. That will tell you all you need to know.

 

[shoot4fun]

Re: OCW test --- interpreting results

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jsthntn247</div><div class="ubbcode-body">Save yourself some time and take the 3 tightest groups and shoot them again at 500+ yards. That will tell you all you need to know. </div></div>

That is not what I would do at all. I would now take the loads in the node you're liking and play with seating depth a little bit. I think that is the next step in the OCW process. Once you have satisfied that then move to step 18 and shoot at distance.

 

[TwoGun]

Re: OCW test --- interpreting results

I see 45.1. The rest I wouldn't care about unless I couldn't duplicate 45.1.

By the way, 45 grains of Varget. Where has everyone seen that before. Duh. Although, generally that's a 168gr load. Guns vary.

 

[Bob 964]

Re: OCW test --- interpreting results

To select 45.1 would appear to be contrary to the plain language of the OCW instructions. I haven't heard anything from anyone familiar with OCW testing to suggest that 44.5 is not the optimal charge weight. If I'm not reading the results correctly, please convince me. Otherwise, I'll test different seating depths using 44.5 gr. of Varget. Thanks for all the input.
Bob

 

[shoot4fun]

Re: OCW test --- interpreting results

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Squarenut</div><div class="ubbcode-body">To select 45.1 would appear to be contrary to the plain language of the OCW instructions. I haven't heard anything from anyone familiar with OCW testing to suggest that 44.5 is not the optimal charge weight. If I'm not reading the results correctly, please convince me. Otherwise, I'll test different seating depths using 44.5 gr. of Varget. Thanks for all the input.
Bob </div></div>

I think you are headed in the right direction.

 

[oldfatguy]

Re: OCW test --- interpreting results

While the 45.1 group is the smallest it does center above the horizontal datum. the 44.1, 44.5 and 44.8 all center around 7:00 and 8:00 in the same quadrent. So according to Dan that is were to start playing with your seating depth.

OFG

 

[prophet]

Re: OCW test --- interpreting results

I agree...44.5 and start to tinker with seating depth. I just shot an OCW today that is almost the same:

10FP-LE2 Savage 26" factory tube (harris bipod from bench)
178 AMAX
Winchester once fired brass (neck sized)
CCI 200 primers
Varget

Mine looks a bit different, but my factory barrel <span style="font-style: italic">is</span> pretty fast, historically averaging 2770 fps with 44.0gr Varget/175 Nosler CC...same other components as listed. Good discussion and Good Luck!

 

[Bob 964]

Re: OCW test --- interpreting results

Welcome to the Hide Prophet, and thanks for your input.

 

[oldfatguy]

Re: OCW test --- interpreting results

If those were my groups I'd have to get out the magnifying glass to pick the "best" place to start.

OFG

 

[chocdog]

Re: OCW test --- interpreting results

yup.
now play with the seating depth and you can really tighten up the grouping.

 

[Bluesop7]

Re: OCW test --- interpreting results

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Squarenut</div><div class="ubbcode-body">To select 45.1 would appear to be contrary to the plain language of the OCW instructions. I haven't heard anything from anyone familiar with OCW testing to suggest that 44.5 is not the optimal charge weight. If I'm not reading the results correctly, please convince me. Otherwise, I'll test different seating depths using 44.5 gr. of Varget. Thanks for all the input.
Bob </div></div>

I agree 100%, I've used OCW method on several loads and it has yet to fail me. I agree with calling 44.5 gr the OCW. Now just do another test with seating depth and you should be good to go with a very tolerant and tight grouping load. Not sure if you have a micrometer seating die but I would highly recommend one for any precision load, especially if your going to be adjusting seating depth in this OCW to find your tightest group.

 

[Bob 964]

Re: OCW test --- interpreting results

Thanks Rebel. I do have and use the (Redding) micrometer seating die.

 

[jsthntn247]

Re: OCW test --- interpreting results

Don't know how anyone is not considering 43.3 the OCW. It is inline with the group before and after it, hence a node, and it is a tight group(doesn't need much seating depth change). Also notice how it resembles the 45.1 group, maybe a high and low node...hmmm.

 

[Bob 964]

Re: OCW test --- interpreting results

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jsthntn247</div><div class="ubbcode-body">Don't know how anyone is not considering 43.3 the OCW. It is inline with the group before and after it, hence a node, and it is a tight group(doesn't need much seating depth change). Also notice how it resembles the 45.1 group, maybe a high and low node...hmmm. </div></div>

It's not that 43.3 isn't being considered, it's whether 43.3 is preferred over 44.5. Both are the middle values of what appear to be 2 pretty good nodes. Given this, I chose the greater of the 2 charge weights.

 

[shoot4fun]

Re: OCW test --- interpreting results

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Squarenut</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jsthntn247</div><div class="ubbcode-body">Don't know how anyone is not considering 43.3 the OCW. It is inline with the group before and after it, hence a node, and it is a tight group(doesn't need much seating depth change). Also notice how it resembles the 45.1 group, maybe a high and low node...hmmm. </div></div>

It's not that 43.3 isn't being considered, it's whether 43.3 is preferred over 44.5. Both are the middle values of what appear to be 2 pretty good nodes. Given this, I chose the greater of the 2 charge weights. </div></div>


Exactly!