OCW Math... Am I close?

[OkieMike]

This is my first foray into a Dan Newberry style OCW test and I picked a combination that doesn't have much in the way of published data.

Components are as follows:
Peterson 300 Win Mag Long brass.
Hodgdon H1000
Hornady 225 gr ELD Match.
Primer: To be determined.
COAL: just under mag length, say 3.58"

The Hornady 10th edition manual does not list a charge for H1000 for the 225 ELDM. So I went to Hodgdon's load data site. Nothing for the 225 there either. But the Berger 230 gr shows a max load of 76.0 gr... I figure the ELDM is 5 gr lighter so this could possibly give me a minor amount of "cushion" in my calculations. And my OAL is nearly .250" over 3.340" book length for 300 Win Mag as well.

So I decided on 76.0 gr as my max.

According to the OCW instructions I back 5 to 7 percent off of max for my starting load. I chose to go with 7% just to be a tad more cautious. So...

76 - 7% gives me approximately 70.1 gr.
Bump up 2% gives me 72.1 gr. And another 2% gives me 73.6 gr. Those are my first 3 "sighters" per the instructions.

Next was bump up another 2% and load 3-4 rounds... So, 4 @ 75.1 gr.

Then it says to go up anywhere from .7% to 1% until I go one increment over my Max charge. I chose .7% just to be careful. So my next 4 are loaded at 75.6 gr. And my last load which is 76.1 gr. which is one increment over my Max load.

So 15 rounds.
1 @ 70.7
1 @ 72.1
1 @ 73.5
4 @ 75.1
4@ 75.6
4@ 76.1

After the first 3 "sighters" the remaining 12 are to be fired "round robin" at the other targets.

This seems a tad bit inadequate. So I am wondering if I screwed up somewhere.

Any advice?

Mike

 

[ShtrRdy]

It's been a long time since I read the OCW paper. So I don't recall what the first three charge weights are for. But where you shoot multiple rounds at a given charge weight I'll agree with the 0.4 grain steps on a 300 WinMag load. It does seem to me that the multiple rounds per charge weight should continue downward since 76 grain is the max.

 

[mtang45]

This is my first foray into a Dan Newberry style OCW test and I picked a combination that doesn't have much in the way of published data.

Components are as follows:
Peterson 300 Win Mag Long brass.
Hodgdon H1000
Hornady 225 gr ELD Match.
Primer: To be determined.
COAL: just under mag length, say 3.58"

The Hornady 10th edition manual does not list a charge for H1000 for the 225 ELDM. So I went to Hodgdon's load data site. Nothing for the 225 there either. But the Berger 230 gr shows a max load of 76.0 gr... I figure the ELDM is 5 gr lighter so this could possibly give me a minor amount of "cushion" in my calculations. And my OAL is nearly .250" over 3.340" book length for 300 Win Mag as well.

So I decided on 76.0 gr as my max.

According to the OCW instructions I back 5 to 7 percent off of max for my starting load. I chose to go with 7% just to be a tad more cautious. So...

76 - 7% gives me approximately 70.1 gr.
Bump up 2% gives me 72.1 gr. And another 2% gives me 73.6 gr. Those are my first 3 "sighters" per the instructions.

Next was bump up another 2% and load 3-4 rounds... So, 4 @ 75.1 gr.

Then it says to go up anywhere from .7% to 1% until I go one increment over my Max charge. I chose .7% just to be careful. So my next 4 are loaded at 75.6 gr. And my last load which is 76.1 gr. which is one increment over my Max load.

So 15 rounds.
1 @ 70.7
1 @ 72.1
1 @ 73.5
4 @ 75.1
4@ 75.6
4@ 76.1

After the first 3 "sighters" the remaining 12 are to be fired "round robin" at the other targets.

This seems a tad bit inadequate. So I am wondering if I screwed up somewhere.

Any advice?

Mike

You followed the OCW instructions to a T. However, I would modify slightly so you can feel comfortable with the range of powder charges you worked with. 75.1 to 76.1 @ a .5 gr jump is just not enough data to make good decisions on the optimum load. I would start at 74 grains and jump .4 between loads, up to 76.4 gr. 74.0, 74.4, 74.8, 75.2, 75.6, 76.0 and 76.4. I generally know when I pull a round and just factor the POI of the two remaining rounds that I shot correctly, so I only load 3 rounds per load. Use the lower charged rounds for sighting and fouling the barrel like Dan suggests. Naturally pay attention to pressure signs as you go up in the charge weights. Stop if you start seeing flattened primers, ejector indentions or swipes on the case head and experience hard bolt lift. I'm thinking that you probably won't see these even at 76.4, but look anyway.

 

[OkieMike]

Thank you for the help.

mtang, that sounds a bit more reasonable to me. Guess I'll start working these up tomorrow.

Mike

 

[supercorndogs]

Charge increments for OCW are .7% to 1%. You should have 5-7 groups to look at for POI, divided by .56-.7 of a grain each.

 

[Doom]

Yep, you’ve got it. If you look at the test below the POI is quite similar on either side of 40.9gr. I was was having to break my setup on each series. In this case the group was also good but that isn’t always the case.

 

[OkieMike]

Charge increments for OCW are .7% to 1%. You should have 5-7 groups to look at for POI, divided by .56-.7 of a grain each.

.7% increments works out to about .5 grain increases.

Mike

 

[culater]

 

[OkieMike]

Went to the range today and tried 'em out... 74.0 to 76.2 gr. Temp was 55° or so, and wind was howling about 16 out of the south... I was shooting W to E, so full value from my right. Kind of a pain.

H1000 gave me about 100 fps more than 4000 MR velocities. Other than that, nothing too life-changing. Got about a pound and a half of H1000 left so not sure how far I'll chase this.

Have a couple pounds of Retumbo too. May crack the cap on a pound and see how it does.

Thank you all for the help

Mike

 

[OkieMike]

Here are the velocity numbers. I may be wrong on this but I'm thinking I need to go back and try charges in the 75.3 to 75.9 range and see if a trend shows up.

The 75.4 would have been great except for the 2898. Not sure where that came from... Scale hiccup, hot primer, tight case, etc... May try loading a few more at that charge with the "offending" case removed from the bunch and see what happens.

Nothing in the way of pressure signs jumped out at me so I could take it beyond 76.2 and see if anything promising shows up.

Thoughts?

Mike

 

[ShtrRdy]

Did you shoot these for groups? What kind of chrono were you using.

 

[OkieMike]

Groups were nothing special... A few better than others. Pro-Chrono DLX.

Honestly I was mainly looking for pressure before anything else.

Mike

 

[mtang45]

Why would you go to all the trouble of asking about your OCW calculations for powder charge, load up the recommended loads, and then go measure a bunch of velocities and no targets?

 

[OkieMike]

Don't get me wrong, I did check groups. Best was just under .625" with ruler. (Edit: Outside to outside of biggest spread minus .308 bullet dia. came up to .555" with calipers. That's OK, I'd like to do better though)

I just wanted better ES with it. Sorry about the confusion.

Mike

 

[Doom]

Mike,
Three shots for SD is pretty meaningless. Check out post #28 at

Stats for velocities and groups.

So why is a 5 shot the standard for groups but not for velocity? I’ve been seeing a lot of discussions lately about SD numbers being useless without a large sample size. I agree that the SD may be unreliable with a smaller sample size but I don’t think it is completely worthless. I use the 5...

www.snipershide.com

 

[impactaddict]

Don't get me wrong, I did check groups. Best was just under .625" with ruler. (Edit: Outside to outside of biggest spread minus .308 bullet dia. came up to .555" with calipers. That's OK, I'd like to do better though)

I just wanted better ES with it. Sorry about the confusion.

Mike

the way I understand OCW is to interpret the position of the groups (POI) relative to the Point of Aim (POA). You'll see the groups trending up/down or left/right but there should be a set of groups (over three sequential but different charge weights) that print similar POI on the target. You're not necessarily looking for small groups at this point (group size is done with seating depth). You're looking for the same POI over a charge weight range.

I'll use your charges 75.6 - 76.0 to make an example.. lets say for those targets (75.6-76) you shot, when the individual groups are overlaid on top of each other they would have a very similar POI and possibly make one respectable group. From there, you can run another charge weight test from 75.6 - 76.2, in smaller increments (.2 increments) to further hone in on OCW. Perform test again and select a charge weight from that set of targets using the same criteria above. From there, you will do a seating depth test to shrink groups.

The point of OCW is to find the node where your barrel shoots regardless of external/environmental factors.

 

[2aBaC̶a̶]

So where is the target? Dont you need a target to read an OCW test?

 

[OkieMike]

Mike,
Three shots for SD is pretty meaningless. Check out post #28 at

Stats for velocities and groups.

So why is a 5 shot the standard for groups but not for velocity? I’ve been seeing a lot of discussions lately about SD numbers being useless without a large sample size. I agree that the SD may be unreliable with a smaller sample size but I don’t think it is completely worthless. I use the 5...

www.snipershide.com

I know. But you always have high hopes that this is the "one" Lol. I loaded up some more and may head to the range and see if I get a clearer picture here in a bit.

I think I may have had some unrealistic expectations for this powder's performance... I need to keep some perspective and do the work. Just aggravating with all the component shortages right now.

I'll keep working on it.

Mike

 

[OkieMike]

So where is the target? Dont you need a target to read an OCW test?

In all of its embarrassing glory...

Mike

 

[impactaddict]

76.0 & 76.2 have a similar POI.. wondering where something like 76.4 & 76.6 would land? not sure if you're at the top end of the load here but it might be worth a shot.

 

[tate1976]

I thought if your going for mv you should do one shot per load not three. I’m pretty new to this sooo be easy

 

[impactaddict]

I thought if your going for mv you should do one shot per load not three. I’m pretty new to this sooo be easy

It's not a bad thing if you're able to collect velocity data while doing OCW testing (assuming you've already done some kind of pressure testing or you're working in manufacturers published loads) but its just not the purpose of the OCW test. It seems smart to do some form of a ladder test prior to OCW to find a good starting place.

 

[Doom]

the way I understand OCW is to interpret the position of the groups (POI) relative to the Point of Aim (POA).

Not really. You compare POI between the Groups using the same POA, but we may be saying the same thing. In Post #19 Mike as two groups, 76 and 76.2 with very similar POI, in fact almost Identical. I would try shooting 76.0, 76.2 and 76.4 and see what happens. Not knowing the shooters ability makes looking at vertical or horizontal spread hard to interpret.

 

[impactaddict]

we may be saying the same thing

we are saying the same thing, just different

 

[OkieMike]

I thought if your going for mv you should do one shot per load not three. I’m pretty new to this sooo be easy

You and me both brother.

Mike

 

[OkieMike]

I got aggravated and ran it again at 75.6, 75.8, 76.0, and 76.2

There were a few changes this time... Far less wind today. I shot from a sturdier bench. And I lined up the targets in a horizontal line... Seemed to make the "round robin" a bit easier as I shifted to make the shots.

And as Doom mentioned... My ability is on the bottom end of non-existent. I readily admit it

Anyway, here is the 2nd try. Working from low to high, left to right...

Mike

 

[OkieMike]

Not really. You compare POI between the Groups using the same POA, but we may be saying the same thing. In Post #19 Mike as two groups, 76 and 76.2 with very similar POI, in fact almost Identical. I would try shooting 76.0, 76.2 and 76.4 and see what happens. Not knowing the shooters ability makes looking at vertical or horizontal spread hard to interpret.

I am also thinking of going up at least one more .2 gr increment... Maybe two if pressure permits.

I know H1000 is supposed to be temp stable. But I'm concerned if I go up much higher in these 50° temps in January, I may run into trouble come summer when it's 100°+.

Mike

 

[impactaddict]

I think one thing to keep in mind when doing this comes from Dan himself...

The OCW load development plan works best with rifles and shooters that are actually capable of MOA accuracy. If your rifle has not shown a propensity for reasonable accuracy, you may want to have it corrected before wasting time and material with additional load developement. If you are not confident that you are at a level where you can shoot consistent MOA groups, you may want to hold off on intricate load development until your skills are better honed. Lots of practice with a scoped .22 LR is invaluable...

Are you capable of shooting MOA?
Is your rifle capable of shooting MOA?

76 & 76.2 still look like they're wanting to group together. The crescent shape you have going @ 76.2 is interesting. Dan might see that and get excited about seeing the next charge up based on videos I've seen of him diagnosing OCW targets. If you can find this high node, there is apparently a lower node 3% lower that works if you're uncomfortable with that higher charge weight.

 

[Doom]

I think one thing to keep in mind when doing this comes from Dan himself...


Are you capable of shooting MOA?
Is your rifle capable of shooting MOA?

76 & 76.2 still look like they're wanting to group together. The crescent shape you have going @ 76.2 is interesting. Dan might see that and get excited about seeing the next charge up based on videos I've seen of him diagnosing OCW targets. If you can find this high node, there is apparently a lower node 3% lower that works if you're uncomfortable with that higher charge weight.

Dropping back to around 74gr may be good idea. But I hesitate to say go there since you are using a fair amount of barrel life. I don’t have experience with the bullet or the cartridge but I suspect that the lower node may be wider, and possibly more accurate. Looking at the 75.4 Target, that looks like a scatter node. If so the accuracy nodes should be around 74.3gr. and 76.4gr. I’m curious about your COL. Being .25” over SAAMI max makes it look like you are chasing the lands in a long freebore chamber. You may need more bearing surface in the neck of the cartridge.

As for the crescent, this may be an issue with the bullet settling in.

What rifle are you shooting? What is the twist? What is your shooting setup, especially the front and rear rests?

 

[GONE BAD]

OP, I have been in your same position.
Back in June I started loading for my rifle.
300WM with max over all length (magazine length) of 3.50.
So I loaded my bullets to 3.498 +/- and added powder in .3 grain starting at 68 grains all the way up to 74. Different powder and different bullet.
My groups and speeds were like yours plus I was having flat primers.

I put 200 rounds through it with no good groups except Hornady factory loads that I used as fouling shots. I would always start with these.
They always shot 1/2" groups from first shot , cold ,clean bore 5 shot groups!

Long story short. I started to shorten up my seating depths and the round shot better.
Finally got down to 3.420 and they were 1 hole groups and drops were tested at 580 yards and at 1004 yards and impacts on rocks were all hits!

This rifle is amazing!

 

[OkieMike]

Dropping back to around 74gr may be good idea. But I hesitate to say go there since you are using a fair amount of barrel life. I don’t have experience with the bullet or the cartridge but I suspect that the lower node may be wider, and possibly more accurate. Looking at the 75.4 Target, that looks like a scatter node. If so the accuracy nodes should be around 74.3gr. and 76.4gr. I’m curious about your COL. Being .25” over SAAMI max makes it look like you are chasing the lands in a long freebore chamber. You may need more bearing surface in the neck of the cartridge.

As for the crescent, this may be an issue with the bullet settling in.

What rifle are you shooting? What is the twist? What is your shooting setup, especially the front and rear rests?

Rifle is bottom tier, nothing fancy... Bergara B14 HMR.
26" x 1:10
Witt Machine brake.

Hornady says a minimum of 1:10 twist for these bullets. I am wondering if my barrel may be on the slow side of a 10 twist and I am right on the edge of being able to barely stabilize them.

As for bench and rest, my local range has no provisions for rifle shooting. If I want to shoot at 100 yards then I am out in a pasture 75 yards behind the 25 yard pistol line. Previous tests were off a cheap POC Caldwell rest... Last test was off of my portable folding bench with bipod and rear bag. Not ideal, but it's what I have to work with. I don't live in the middle-of-nowhere, but I can see it from here. Better facilities require a drive of hours.

COAL is 3.554" (CBTO 2.758") I used this because it had worked decently with this bullet using different powder and fit inside my magazine (3.600" max coal) So it was merely a starting length. I had planned on trying to tune via seating depth once a load showed some kind of merit. I can go longer and single feed if concensus dictates... But I would really prefer to use the magazine if I can.

I am on the downhill side of this barrel's life. Still a little ways to go, but it isn't brand new. So at this point I may be better served abandoning this and just going back to my established load and finishing off this barrel.

I noticed with the 76.0 grain group that 2 were through the same hole and 2 were touching... I see this on occasion with my .308 as well. This leads me to think I need to work on fundamentals with "driving" the rifle itself. But you won't know if you're improving on how you drive the gun if you aren't sending good ammo down the tube either.

So there it is. I am just a guy with low level to piss poor equipment struggling through this at sub par facilities learning by trial and terror. But I don't have it in me to quit, and figure if I can get somewhat decent results with what I have then I can only get better as I upgrade.

The plan, in spite of all the shortcomings, was to try and find a powder node that worked and then tune my seating depth... But I may be way off. Still new to this.

Mike

 

[Doom]

...with no good groups except Hornady factory loads that I used as fouling shots.

Not a good idea to mix ammunition when testing, as some powder combinations don’t play well together and create rapid fouling issues.

Mike,

Not a bad rifle at all. I don’t think the twist is an issue and as you noted those 76 gr shots don’t indicate a rifle issue.

When you are shooting, is the rifle responding the same on every shot? Is the recoil straight back or does the rifle jump to one side? When the trigger breaks do you hold it back until everything has settled? Answers my shed some light on your impact.

I would not shoot five shots groups. Someone once said “3 shots test the rifle/load, five shots test the shooter”. Might have been Dan. I have personally found this to be true.

 

[OkieMike]

When you are shooting, is the rifle responding the same on every shot? Is the recoil straight back or does the rifle jump to one side? When the trigger breaks do you hold it back until everything has settled? Answers my shed some light on your impact.

Ideally I would like to say 'yes' but I can't say it with 100% certainty... I shoot flintlock guns too so I know the importance of follow through. But a 45 cal longrifle doesn't quite recoil like a 300 Win Mag either.

I do my best to keep recoil in a straight line back to me, but I can't guarantee I do it all the time... may have my wife start videoing me as I take shots and see if I can 'autopsy' my technique.

I'll certainly stick to 3 round groups from here on out.

I appreciate the advice. There's probably a whole host of things I'm doing wrong. Might be time to save my pennies and take some of Frank's classes/courses.

Mike

 

[Doom]

Sounds like you have a handle on things. One thing is for sure, you have your hands full developing loads for the 300WM. After all this I would load 76.2 and go with it. It may not be the center of the node but both 76 and 76.2 have a consistent pattern on two separate test. It’s definitely a shootable load.

 

[impactaddict]

Agree'd.. I think you found a node but I would like to see 76.4 printed on paper with the same seating depth that you've been testing.

Also according to Dan's theory, there is another slower node around 74gn (76.2 -3%).. might want to test that too while you're at it.

 

[OkieMike]

Thanks folks, I appreciate the help.

Headed out of town for a few days so further testing will be on hold.

Mike

 

[OkieMike]

Agree'd.. I think you found a node but I would like to see 76.4 printed on paper with the same seating depth that you've been testing.

Also according to Dan's theory, there is another slower node around 74gn (76.2 -3%).. might want to test that too while you're at it.

Been a minute. But I managed to get out today and try some of the suggestions...

76.2 gr I put 2 through basically the same hole, but pulled the last shot... Knew it as soon as I did it. I cussed loud enough for everyone around to hear me.

76.4 looked great too... And I managed not to pull one.

Mike

 

[ShtrRdy]

That looks pretty good but why is the point of impact different?

 

[GONE BAD]

From the looks of it I'd say he made a dope change and went the wrong way?

 

[OkieMike]

That looks pretty good but why is the point of impact different?

From the looks of it I'd say he made a dope change and went the wrong way?

Hell, I don't know. I didn't adjust the scope. 2 different dots... May have been me.

Mike

 

[Doom]

I can’t say for sure but I think the POI shift is due to the shooter. I’m willing to bet the two groups were not shot round robin and the shooting position was broken between groups.

 

[OkieMike]

I can’t say for sure but I think the POI shift is due to the shooter. I’m willing to bet the two groups were not shot round robin and the shooting position was broken between groups.

Correct. I didn't do round robin this go round.

Mike