Range Report OCW results. thoughts?

[taseal]

Last time I tried to OCW the gun, it was october I think... as you can tell I don't have much time to hit the range lately unfortunately.

last time I did this, I made a thread about it, which you might want to take a look (it's on practical riflery where Dan hangs at) I'm putting this on a new thread becuase they're new results, and the thread isn't 6 months old. give me your thoughts. based on my last results Dan recommended I try the charges that I used today. so check these out and let me know what you think! the lower charge was incase 53 was running hot (my rifle tends to give pressure marks easy) so I did low and high charges. 53 seemed to be ok with no overpressure signs.

I think my ideal charge here is 53.6... 53.3 and 53.6 are pretty close to each other. perhaps 53.9 would verify, but I didn't have that charge, so I'm going to say 53.3 is my load

<span style="font-weight: bold">Rifle specs</span>
Trued R700 LA .30-06
Rock Creek SS 5R 26" 1:10 M24 barrel
B&C A2 Stock w/Atlas Bipod and homemade rear bag from a sock

<span style="font-weight: bold">Load Specs</span>
H4350 (50-53gr in .5 increments) with 208 amax. 3.459 OAL with Lapua Brass and FGMM primers (.01 off lands)
First I did the foulers (3x50gr) then started with 49.5-50.50.5

Then I did the 53-53.3-53.6 (There is one missing on the 53.3 because I ended up striking the metal bar thingy on my chrono with it... OOPS! )

So here we are...

 

[Hoverp]

Re: OCW results. thoughts?

Please try your test further out, like 200 or 300 if able.

 

[taseal]

Re: OCW results. thoughts?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Hoverp</div><div class="ubbcode-body">Please try your test further out, like 200 or 300 if able. </div></div>

unfortunetly the closest >100 range is a 2 hour drive. I will try that when I'm able to go that way though.

Thanks...

 

[RemingtonSPS]

Re: OCW results. thoughts?

I would be loading 50.3, 50.5, and 50.8 grains. That 50.5 charge seems to have the least vertical and loading to either side of it in .3gr increments might show you a good node. For OCW or ladder testing its best to start at a minimum of 300yds (i prefer 500yds). If all you have access too is 100yds, i would invest in a chronograph and shoot these loads for ES and SD.

 

[DCR]

Re: OCW results. thoughts?

Definitely a node at 50. Can't really tell with the other 3. 53.3 missing a shot an all. You're node could be at 53.3 or 53.6. Maybe reshoot those?

 

[shoot4fun]

Re: OCW results. thoughts?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MuleHunter</div><div class="ubbcode-body">I would be loading 50.3, 50.5, and 50.8 grains. That 50.5 charge seems to have the least vertical and loading to either side of it in .3gr increments might show you a good node. For OCW or ladder testing its best to start at a minimum of 300yds (i prefer 500yds). If all you have access too is 100yds, i would invest in a chronograph and shoot these loads for ES and SD. </div></div>

I agree with your assessment of where to go on loads in continuing to tune tis up but you have to remember that 300 to 500 yds is not for everyone. if the OPs shooting is limited to shorter ranges then that is what he should use for his testing. Two reasons I see; one is he may not have the skill you do in shooting at longer ranges (especially for an OCW) and the other is 100 yards actually seems to be building an optimal load for the distance he shoots the most.
Why does everyone (except Newberry) feel the OCW must be done at long range to be of value?

 

[RemingtonSPS]

Re: OCW results. thoughts?

For ocw and ladder testing you are looking for rounds that group together vertically, this shows two things, one that you are at the right spot for barrel harmonics, and two that you have good ES and SD. Since these effects are exaggerated at longer ranges its best to do this testing at longer ranges. If his shooting is primarily at 100yds but he wants a load that would be good for longer ranges when he gets the opportunity to shoot farther (which was the impression I got) then he would benefit from a chronograph as ES and SD is important at longer ranges. To illustrate I once developed a load with Scenars that would consistently print sub 1/4 minute at 100yds. When I shot that load at 600yds it opened up to 1 1/2 moa of vertical. At 100yds the Extreme Spread of velocity was not a problem, at 600 it was. Had I chronographed that load first at 100yds I could have saved myself the trouble at 600.

If he only plans on shooting 100yds then you are right, keep developing until you bughole at 100.

 

[DCR]

Re: OCW results. thoughts?

OCW is about a forgiving load. You are looking for a change in point of impact between different groups not vertical dispertion. You don't even take into account group size. You fine tune group size with seating depth after you find your node. There is a pretty easy step by step on newberry's web site....that I dont have handy at the moment. I would definately verify at all ranges you expect to shoot when done load testing.

 

[RemingtonSPS]

Re: OCW results. thoughts?

OCW is not complicated, it is simply finding a spread of charge weights that group together and picking the middle charge. That gives you the best harmonic node. The only difference between OCW and ladder testing is that with ladder testing you are fine tuning to a specific 'rung' or charge weight.

The problem with OCW only is that you may pick a load that has high ES and SD but still groups together. If you are only shooting at 100yds it is irrelevant. If you plan to shoot longer ranges but develope the load at 100yds then a chronograph is helpful.

I feel like i didn't explain myself well enough the first time...i appologise if i was being a little redundant.

 

[DCR]

Re: OCW results. thoughts?

Yes it is a fine dance we have to play isnt it?

 

[gstaylorg]

Re: OCW results. thoughts?

http://optimalchargeweight.embarqspace.com/#

 

[taseal]

Re: OCW results. thoughts?

I'm confused as to why you guys are reccomending 500 yards for OCW testing... and also linking me to the website for newberry.

I got the information about OCW on his website (is it even available anywhere?)

and newberry himself says that 100 yards is sufficient if you can't get to a longer range.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">
I prefer to shoot the initial stage of OCW testing at 100 yards. This will factor out most of the wind effect. In the overwhelming majority of cases, 100 yard data is easily interpreted, and more easily obtained. Many shooters don't have immediate access to 300 yard ranges. From my own experience, I can tell you that if you properly interpret your 100 yard targets you'll have an excellent 300 yard (and even farther) load recipe. <span style="font-weight: bold">Almost every load I've developed at 100 yards has printed MOA or better at 300 yards. Some of these loads have done extremely well at 600 yards and farther... the following group was shot at 1062 yards using a load developed at 100 yards.</span></div></div>

 

[taseal]

Re: OCW results. thoughts?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MuleHunter</div><div class="ubbcode-body">OCW is not complicated, it is simply finding a spread of charge weights that group together and picking the middle charge. That gives you the best harmonic node. The only difference between OCW and ladder testing is that with ladder testing you are fine tuning to a specific 'rung' or charge weight.

The problem with OCW only is that you may pick a load that has high ES and SD but still groups together. If you are only shooting at 100yds it is irrelevant. If you plan to shoot longer ranges but develope the load at 100yds then a chronograph is helpful.

I feel like i didn't explain myself well enough the first time...i appologise if i was being a little redundant.</div></div>

Jesse,

problem is I can't get an accurate ES from 3 shots of the same charge. I need 10 or so to get good ES/SDs as you know I'm sure...

I can't make 10 rounds for every charge and keep testing. that's too much work, that's hundreds of rounds of testing. and with quality powder and being at a common charge area, your ES and SD should not deviate like crazy (please correct me if I'm wrong)

I do have a chrono and I can tell you that my 50gr was between 2494-2487 for the 6 of them that I shot

I truly appreciate the input though. however this thing won't see a range past 100 for a while. I'll load 10-15 50gr loads and see what the ES and SD will be

I've been talking with the creator (Dan) on his forum and we decided we're going to stick with 50gr

50gr will get me to 2500fps and it has been very consistent since this and last time.

2500fps means 1250 to subsonic, so I should have no problem ringing steel at 1000y with it

53.3 was 2646fps and I don't think the speed gain is going to do much for me.

 

[jsthntn247]

Re: OCW results. thoughts?

By looking at your test, I would load at 53.5 in varying seating depth's. You also have a lower node at 50.2 in which I would at diff seating depth's also.

 

[Ol' RD]

Re: OCW results. thoughts?

Actually you can get a fairly accurate ES and SD from a 3 shot group. In Denton Bramwells artical "The Perverse Nature of Standard Deviation" he uses multiplying your SD by 1.693 if your sample size is 3. It a great article, if you can't find it PM me and I will send you a copy.

 

[gilgamesh1]

Re: OCW results. thoughts?

When I have tried OCW in the past, I tested more than 3 successive loads. More like 6; I like to see a definitive shift in group location. It looks like the higher node might be between 53.3-53.6 but it'd be nice to have more groups on either side. I try to shoot the targets all at the same horizontal level, in a round robin fashion just as suggested in the above mentioned link http://optimalchargeweight.embarqspace.com/# to remove confounding factors. I have found a low and high node for my 308, but had to repeat the process to convince myself that those were the real nodes. There is some subjectivity in the analysis, at least for someone with my limited shooting skills.

I do think that OCW can be done at 100yds and maybe it should be done at 100 rather than 300 or whatever. Because you are looking for shift in group location not group size. Further ranges introduce confusion with more dispersion and more wind effect.

As an aside, I did not find Newberry's comment on distance from the lands being unimportant for accuracy to be true with the 155 scenars that I now use.

 

[Leaddog]

Re: OCW results. thoughts?

It's hard to get much more than just preliminary information from 3 shot groups at 100 yards. Saying that, I would go 2 tenths either side of 50.5, including 50.5, with 5 shot groups.

If your quest is the best accuracy you can obtain from your rifle, you must go further out and use a chrono. 300 - 400 yards seems ideal. Once you find your load, take along 25 rounds seated long and reset the seating depth at the range using an arbor press and and Wilson mic die. I can't emphasize the use of a chrono more. It's the only way to find out what you have. I use an Oehler 35P.

Good shooting!