First OCW Test

[CxAgent]

I received a reloading setup for Christmas and loaded 30 rounds with Varget and 175gr Hornady BTHP. Went out today and shot an OCW. I think I know what I am looking at forresults but would like some input on where you would start for load development and fine tuning. Worked up from 42.5 gr to 45gr. My next outing I was planing on Loading 5 rounds each starting at 44.4 up to 45 grains.

Where would you look and what would your next steps be keeping in mind I don't have a chrono yet.

Your input and help is appreciated.
If it helps this was shot with the .308 RPR loaded to max mag length 2.810 once fired FGMM brass and FGM primers. Neck was bumped .0015

Thank you in advance

 

[GrandpaDeadLegs]

I believe you are looking for the best vertical spread at this step - 44 seems all in a line - mixed with overall tightest at 44.8.

A chrono will be useful.

Keep it up!

 

[pell1203]

CxAgent,
From what is visible here, if it were me, I’d try from 44.0 to 44.8 in 0.2 grain increments. Things seem to open up fast and impact points seem to shift quickly starting at 45.

You may also have another slightly slower node whose center may be near 42.5 or just slightly below that.

 

[ShtrRdy]

I like to look at group location. Compare group location from one load to the next and if they are in the same location, take a look at group size of each load. If there's a small-ish group along with another group printing in the same location I'll fine tune around that load recipe.

 

[Deleted member 10043]

If you don't have a chronograph and there are no pressure signs at 44.8 than all you need is to check again for best seating depth and you're done. I would bet you're all set just with that load with no further testing needed.

 

[stello1001]

I like 44.4 to 44.8...

 

[supercorndogs]

I would run a seating depth test on 44.4, by shooting some 5 shot groups. Then I would chronograph it to confirm SD, and shoot some groups at 600.

 

[spife7980]

Seating depth test on 44.6 now

 

[Brandon05_88]

I'll echo 44.6 and a seating test. I've consistently ran 44.6 Varget with a 175 in Lapua brass. Federal is in the same neighborhood.

 

[CxAgent]

Thanks to all who responded! I suspect the 44.6 grain was pointed out because the group falls within or close to both the 44.4 and 44.8. When I take the target data and use a composite group I get approximately .903 MOA between the three. If I exclude the low shot at 44.6 ( I know that was a bad shot and all me) it drops the composite group to a .594 MOA.

As for the seating depth test; this first round of testing was at max mag length with the stock RPR mags. I know I can get mags that will accommodate longer lengths. Would you start at max length and go shorter? I do have a comparator and can measure to the lands would you start there and how much would you set the bullet back from the lands?

Thanks again, all the help is very much appreciated!

 

[spife7980]

The stock RPR mags are awfully constrictive, Get the AICS style magpul mag and youll have much more real estate available to you.


I would find the distance to your lands, see where that is actually at. Do you know how to do that? If not let us know and we can show you a few methods to do so.


If the distance to your lands is longer than mag length then I would test from 2.8880 Case Over All Length (COAL or OAL is the shorthand) and shorter. Some of those longer ones may be too long for your LR/SR mag but you can single feed them and if they shoot best at that longer length then you can get the AICS style mag.

If the distance to your lands is shorter the 2.880 OAL then that then I would start .010 short of the land measurement and then test shorter from there. Since its a field rifle I wouldnt want to jam bullets, that can leave an unfired round with the bullet stuck in the barrel.

The LR/SR mags allow 2.830 OAL

The AICS style mags allow 2.880 OAL

 

[supercorndogs]

You could take the length you have and go to the 600y line and see if your happy. It looks like you are in pretty good territory, with OCW hypothesis saying you have node from 44-44.8 and you want to be some where in the middle.

 

[lash]

I believe you are looking for the best vertical spread at this step - 44 seems all in a line - mixed with overall tightest at 44.8...
...Keep it up!

Uhm, no.

Read this and the associated links pertaining to OCW:
http://optimalchargeweight.embarqspace.com/

 

[Deleted member 113831]

I received a reloading setup for Christmas and loaded 30 rounds with Varget and 175gr Hornady BTHP. Went out today and shot an OCW. I think I know what I am looking at forresults but would like some input on where you would start for load development and fine tuning. Worked up from 42.5 gr to 45gr. My next outing I was planing on Loading 5 rounds each starting at 44.4 up to 45 grains.

Where would you look and what would your next steps be keeping in mind I don't have a chrono yet.

Your input and help is appreciated.
If it helps this was shot with the .308 RPR loaded to max mag length 2.810 once fired FGMM brass and FGM primers. Neck was bumped .0015

Thank you in advance

Having loaded many thousands of this combo, I can tell you that you are hitting high pressure at 44 grains, maybe not max, but your primer pockets are going to open up after about 4 firings. Your target shows it also with a major POI shift. There is very often a node between 44.0 - 44.4 grains in this range. But it can be finicky, and it will cost you in brass life.

On the lower pressure band, there is often a node at 43.5 to 43.7. This give good velocity and is easy on brass and has a more consistent POI at different temps. Looking at your test, there is a very consistent POI between 42.5 and 43.7. Only a single shot out 12 is outside of a very narrow vertical band. I would not let this one single shot influence any decision making, It is the picture as a whole we are looking at.

At this stage, group size is almost completely irrelevent. You are looking for POI variation in group centers only.

Good shooting

 

[GrandpaDeadLegs]

Uhm, no.

Read this and the associated links pertaining to OCW:
http://optimalchargeweight.embarqspace.com/

Shit sandwich I better start fact checking what I learn on the Hide a little more... Look hard enough and what I said was told to someone else a while ago. Back to keeping my mouth shut I guess for a while! Thanks lash

 

[CxAgent]

The COAL averages 2.900 from six measurements. This was using a fired case with a slit cut into the neck. With the Hornady OAL gauge I was getting a reading of 2.910. The Base to Ogive with the Hornady 175 Gr BTHP measures 2.329.

Looks like I am ordering AICS mags today. This would give me .020 off the lands at max mag length.

What are you opinions or thoughts?

 

[lash]

Shit sandwich I better start fact checking what I learn on the Hide a little more... Look hard enough and what I said was told to someone else a while ago. Back to keeping my mouth shut I guess for a while! Thanks lash

No, don’t keep your mouth shut. Your intent is to help others and that’s a good thing. Sometimes learning hurts a bit, but you’re learning nonetheless.
I really do suggest that you read the process though. I’ll admit to having to go back and read through it a couple times until I understood what was going on and what I was trying to accomplish. No shame in that.

And BTW, I’m pretty sure that there are more people touting OCW who do not understand it than those that do. So you are not alone.

FWIW, @Skookum just above summarizes it pretty well in this post:

Having loaded many thousands of this combo, I can tell you that you are hitting high pressure at 44 grains, maybe not max, but your primer pockets are going to open up after about 4 firings. Your target shows it also with a major POI shift. There is very often a node between 44.0 - 44.4 grains in this range. But it can be finicky, and it will cost you in brass life.

On the lower pressure band, there is often a node at 43.5 to 43.7. This give good velocity and is easy on brass and has a more consistent POI at different temps. Looking at your test, there is a very consistent POI between 42.5 and 43.7. Only a single shot out 12 is outside of a very narrow vertical band. I would not let this one single shot influence any decision making, It is the picture as a whole we are looking at.

At this stage, group size is almost completely irrelevent. You are looking for POI variation in group centers only.

Good shooting

See bolded and underlined statement.

 

[Deleted member 113831]

Shit sandwich I better start fact checking what I learn on the Hide a little more... Look hard enough and what I said was told to someone else a while ago. Back to keeping my mouth shut I guess for a while! Thanks lash

You weren't wrong, it's just ordered priorities. You quoted a particular indicator out of order of precedence. Vertical dispersion of individual groups is an important consideration, just not at this stage of the process.

 

[CxAgent]

Shit sandwich I better start fact checking what I learn on the Hide a little more... Look hard enough and what I said was told to someone else a while ago. Back to keeping my mouth shut I guess for a while! Thanks lash

We are all learning here and I appreciate the feedback.

 

[GrandpaDeadLegs]

I used to have a job where I was the skookum, lash, and lowlight for the entire state when it came to certain lame ass matters of non-native vegetation so I am probably just missing the helpfulness... Now I run a chainsaw alone in the woods and have an obscene amount of free time... Usually armyjerry bears the brunt of my boredom

 

[DrewC]

I’d say from looking at that pic I’d load up 43.1 to 43.9 in .2 gn steps and shoot. Looks to me 43.5 would be my guess.

 

[jsthntn247]

Play with seating depth at 44.4 as corndogs said.

 

[CxAgent]

So it appears there are two Pressure bands or accuracy nodes whichever is the correct way to word it. From the feedback it seems that somewhere around the 44.4 - 44.6 would be a place to investigate realizing that this area has greater pressure and will most likely result in shorter case life.
43.5 to 43.7 would be a lower pressure band or accuracy node to investigate. This would result in a better case life.

One of the reasons I went with Varget is from reading that is was pretty temperature tolerant. This test was conducted at 23F. What type of increase could one expect at 75F or 90F. I had found testing from an individual who tested at 0F and 100+ F and the change was minimal. Would this be consistent or was that more an exception?

Anyway, I loaded 5 rounds of each from 44.3, 44.5, and 44.7 just to see what they will do. I did not change seating depth.

Also loaded up 3 rounds each of 43.1, 43.3, 43.5, 43.7, and 43.9. Same length as original test. I will look at the results and see what I can identify from this group.

If nothing else I am learning the new equipment and getting out shooting.

 

[Deleted member 113831]

In my experience, Varget is about 0.35 fps per degree from 30 - 80 degrees on average. This varies lot to lot, but is a decent starting point. All powders start to speed up when the temps reach 80+ degrees. Some more than others, but none are immune.

 

[pell1203]

FWIW, my Rem 700 .308 5R Mil-Spec loads with Varget and same 175gr. Hornady BTHP bullet are 43.3 gr. and 44.5 gr. for the two speed/accuracy nodes being discussed here. COAL is in 2.825” range so it can fit in rifle’s internal magazine.

 

[CxAgent]

FWIW, my Rem 700 .308 5R Mil-Spec loads with Varget and same 175gr. Hornady BTHP bullet are 43.3 gr. and 44.5 gr. for the two speed/accuracy nodes being discussed here. COAL is in 2.825” range so it can fit in rifle’s internal magazine.

Good to know. I have different mags coming that will allow a longer seating depth.

 

[HeadHunter10]

Uhm, no.

Read this and the associated links pertaining to OCW:
http://optimalchargeweight.embarqspace.com/

lash,
After reading this article I was wondering if you could clear a few things up for me. My understanding from what I have read elsewhere is that you want consistent velocities, regardless of group size when developing the load. Then once you find the charge weight that provides consistent results with low es and sd, you play with seating depth to tighten up the groups. This article suggests the opposite; find consistent groups disregarding es and sd, then fine tune those with seating depth. Are these just two different schools of thought (traditional OCW vs. Satterley type ladder test) or is my understanding completely wrong? Also, what is your experience following the steps outlined in the article?

Input from anyone else is also appreciated

 

[supercorndogs]

lash,
After reading this article I was wondering if you could clear a few things up for me. My understanding from what I have read elsewhere is that you want consistent velocities, regardless of group size when developing the load. Then once you find the charge weight that provides consistent results with low es and sd, you play with seating depth to tighten up the groups. This article suggests the opposite; find consistent groups disregarding es and sd, then fine tune those with seating depth. Are these just two different schools of thought (traditional OCW vs. Satterley type ladder test) or is my understanding completely wrong? Also, what is your experience following the steps outlined in the article?

Input from anyone else is also appreciated

In OCW you are looking for a similar POI over a range of charge weights. Not groups, not vertical spreads, not low SDs, POI. Groups and SDs, are tested and tuned with length. After you find a charge weight, preferably with the largest charge weight range with the same POI. You park in the middle of that window. You tune length, if you feel the need. If your groups aren't great, adjusting the length can make a big difference.

 

[Deleted member 113831]

The OCW test (Dan Newberry's method) is basically a test of barrel timing. An optimal barrel timing will compensate to a certain extent for slightly inconsistent velocity. However, depending on where the barrel is in it's movement, it may or may not hold up at distance.

Longrange Benchrest guys do ladder tests at distance (Audette method) because there is only a single range they are worried about. They couldn't care less what groups look like at 100 or 500 yards. They will tolerate whatever ES and SD they get within reason as long as the vertical is tight. There is a principle at work here referred to as "positive compensation" that comes into play when doing this type of testing.

Longrange field shooters have to worry about near and far, so SD and ES are important along with dispersion at all ranges.

Seating depth changes the shape and size of the group regardless of method or powder charge.

I load first for numbers. Consistent SD's and good velocity are most likely to show up within 3% of max charge FOR YOUR RIFLE. I then adjust seating depth and test the final choice by shooting 4 groups of 5 shots at 200 yards. If the load passes that test, it is most likely good to go.

You will get your feelings hurt though to see what 20 shots looks like at 200 from your "1/2 moa all day" rifle, I guarantee it. But you will know the truth.

 

[lash]

The OCW article absolutely does not suggest that you go for group size or even “consistent groups”, whatever that is. If you read all of the linked articles associated with that article, you will eventually come to the understanding that what you are doing is looking for “nodes” wherein the “average” points of impact of two or three consecutive loads are similar/same in elevation to each other.

What you will see, if you shoot a large enough spread of loads, is that average poi for the “groups” will move up and down in a somewhat cyclical manner with plateaus where two or three consecutive loads share the same poi elevation, as per above. These nodes are where you want to look for your load. You pick one at the pressure level you are comfortable with, ideally the one in the center of a node if you are at an average shooting temperature for your area, and then work on seating depth if needed to tighten actual shot groups.

You’ll notice that I put quotations around the word “groups” above. That is to point out that these groupings are not shot as groups, but are shot round robin style in order to allow for variations in barrel temperature and ambient temperature during the period you are doing your OCW.

If you spend some time to consider how this works and the intended results, you’ll see that the Saterlee velocity method, while different, is accomplishing a similar result. In both cases, you are looking for plateaus that allow you to create a load that should shoot the same no matter the local ambient conditions, that will be forgiving of less than perfect charge weights (who cares if that scale is throwing charges +/- 0.05 grains anyway?), and that you may not have to change when you open a new can of powder.

I am not selling one method over another, as they both seem to work well. I am personally comfortable using OCW, so will continue using it until or unless something truly better comes along.

Btw, both methods about share similarities with the older method of ladder tests used for years.

 

[Deleted member 113831]

The main problem with all these methods is the number of people doing them vs the number of people that actually understand them.

Satterlee's method is least understood of all. When Scott hits his "flat spots", he is within 1% of max charge. In other words, the flat spots happen because he has reached the point of diminishing returns that comes with 100% load density.

He uses slower powders and heavy for caliber bullets. It makes perfect sense in that context.

But almost nobody gets that part. They see flat spots that are simply the random artifact of overlapping ES from one charge increment to another.

 

[Boatninja]

The stock RPR mags are awfully constrictive, Get the AICS style magpul mag and youll have much more real estate available to you.


I would find the distance to your lands, see where that is actually at. Do you know how to do that? If not let us know and we can show you a few methods to do so.


If the distance to your lands is longer than mag length then I would test from 2.8880 Case Over All Length (COAL or OAL is the shorthand) and shorter. Some of those longer ones may be too long for your LR/SR mag but you can single feed them and if they shoot best at that longer length then you can get the AICS style mag.

If the distance to your lands is shorter the 2.880 OAL then that then I would start .010 short of the land measurement and then test shorter from there. Since its a field rifle I wouldnt want to jam bullets, that can leave an unfired round with the bullet stuck in the barrel.

The LR/SR mags allow 2.830 OAL
View attachment 7003824


The AICS style mags allow 2.880 OAL
View attachment 7003825

I'll bite, how do you determine the distance to the lands? This shit is making my head hurt. As with most things, the more I learn the more I learn that I don't know and that there is more to learn.

 

[Deleted member 113831]

I'll bite, how do you determine the distance to the lands? This shit is making my head hurt. As with most things, the more I learn the more I learn that I don't know and that there is more to learn.

Take a case and just barely size the rim of the neck, or take a sized case and cut a slit down the neck.

Take a bullet and color it with a Sharpie and finger seat it in the case snd chamber it. If the bullet stays in the case you can measure it there. If not, the scraped off marker will show you how far the bullet seated before it got pulled out of the case.

 

[Onyx Z]

I'll bite, how do you determine the distance to the lands? This shit is making my head hurt. As with most things, the more I learn the more I learn that I don't know and that there is more to learn.

This work very well and zero specialty tools required.

 

[spife7980]

This work very well and zero specialty tools required.

Could be tough in the RPR, I know my cousin had trouble getting the bolt to fall freely by itself so there was always some tension on it. He used a sharpie to check it with this method.

But yeah, this wheeler method is what Ive defaulted to.

 

[HeadHunter10]

The main problem with all these methods is the number of people doing them vs the number of people that actually understand them.

Satterlee's method is least understood of all. When Scott hits his "flat spots", he is within 1% of max charge. In other words, the flat spots happen because he has reached the point of diminishing returns that comes with 100% load density.

He uses slower powders and heavy for caliber bullets. It makes perfect sense in that context.

But almost nobody gets that part. They see flat spots that are simply the random artifact of overlapping ES from one charge increment to another.

I thought that Saterlee talked about a higher and lower velocity “flat spot”. How can there be a lower velocity node if he only hits it within 1% of his max charge? Also, how can I then be sure that when I find what I think is a velocity node while doing .2 gr incremental increase test that I am actually seeing the type of flat spot that I am looking for and not just a random overlapping of the ES?

Btw, thanks for all of the input.

 

[Deleted member 113831]

If you go back and watch the 6.5 Guys video closely you will see that he was running RL26 with 140's in a 6.5 Addiction (Sweedmoor). This cartridge has a very short throat, and he was running them 0.010" off the lands.

He pressured out at 52 grains, and the "flat spot" he chose was 51.4 - 51.8 grains. So the middle of that flat spot was 1% off max. The other flat spot was 50.2 - 50.6 grains. Which was still within 3% of max pressure. In my experience this concurs perfectly with what I've seen in other cartridges. There is a lower node right around the 2% - 3% of max, and a higher node right around max. I always load for the lower one but some people have to have the speed.

One other observation...if you go back and watch the video, when it shows Scott actually shooting his rifle from the prone, you will see that his bolt is sticking at the top and it takes some effort to get it to extract. He is definitely pushing max.

 

[Brentc]

Look at the scatter node at 45 grains. All you have to do is multiply 45 x .985. The calculated high node OCW is 44.3 grains.

Based on further calculation, Your low node will be 43 grains.

 

[DrewC]

44.3 is overpressure in fed brass.

 

[Onyx Z]

Look at the scatter node at 45 grains. All you have to do is multiply 45 x .985. The calculated high node OCW is 44.3 grains.

Based on further calculation, Your low node will be 43 grains.

What do these calculations mean and where did .985 come from?

 

[CxAgent]

Look at the scatter node at 45 grains. All you have to do is multiply 45 x .985. The calculated high node OCW is 44.3 grains.

Based on further calculation, Your low node will be 43 grains.

Would you explain more. I will definitely investigate both nodes. I would like to understand the .985 and how you came up with the 43 low node. Trying to learn all I can.

 

[Brentc]

OCW nodes, accuracy or scatter are ~3% powder charge apart. Accuracy nodes alternate with scatter nodes.

A scatter node is opposite of an accuracy node and it falls halfway between the accuracy nodes.

When you find a node, accuracy or scatter, you can predict where the next node will appear by adding or subtracting the appropriate percentage to your current charge to find your next node.

Since you found a scatter node, or often times called a scatter group, all you have to do to get into an accuracy node is add 1.5% to get into the next higher accuracy node. If you want the lower node, subtract 1.5%

Does this make sense?

The .985 number comes from subtracting .015 (1.5%) from 1. Multiplying the scatter charge by .985 will give you the lower accuracy node.

If you want to find the higher node, multiply your scatter charge by 1.015.

I'm using 44.3 to predict where your lower node will be. 44.3 x .97 = 43

 

[Deleted member 113831]

OCW nodes, accuracy or scatter are ~3% powder charge apart. Accuracy nodes alternate with scatter nodes.

A scatter node is opposite of an accuracy node and it falls halfway between the accuracy nodes.

When you find a node, accuracy or scatter, you can predict where the next node will appear by adding or subtracting the appropriate percentage to your current charge to find your next node.

Since you found a scatter node, or often times called a scatter group, all you have to do to get into an accuracy node is add 1.5% to get into the next higher accuracy node. If you want the lower node, subtract 1.5%

Does this make sense?

The .985 number comes from subtracting .015 (1.5%) from 1. Multiplying by .985 will give you the lower accuracy node from the scatter charge.

If you want to find the higher node, multiply your scatter charge by 1.015.

Using your system 43.6 grains should be a scatter node, yet 43.5 - 43.7 is an accuracy node in a multitude of rifles.

 

[CxAgent]

Thank you. I have been reading all I can and this is new. I appreciate the explanation.

 

[Brentc]

Using your system 43.6 grains should be a scatter node, yet 43.5 - 43.7 is an accuracy node in a multitude of rifles.

I don't doubt it. Im going by what I see on the target and applying Newberry's system.

 

[Deleted member 113831]

It's not my system. It's Newberry's.

Also, look at his target. Things are going haywire between 43.3 and 43.7. A lot of things affect where the nodes will end up. Seating depth, brass, primers, etc.

What I see is a single dropped shot. From 42.5 to 43.7grains, 11 out of 12 shots are within the same 1 inch wide horizontal band. You could lay a strip of masking tape down and cover all but 1 of them.

Like I said before, having shot many thousands of this exact recipe, I can say that 44 grains is getting into high pressure. There is often a high node at 44 - 44.4 grains but it will cost you in brass life. 4 firings if you are lucky.

 

[DIBBS]

This is all very informative and better helps me understand the ladder test. I'm going to keep my mouth shut, read more, and do a little testing of my own with another caliber or two this weekend.

 

[Brentc]

What I see is a single dropped shot. From 42.5 to 43.7grains, 11 out of 12 shots are within the same 1 inch wide horizontal band. You could lay a strip of masking tape down and cover all but 1 of them.

Like I said before, having shot many thousands of this exact recipe, I can say that 44 grains is getting into high pressure. There is often a high node at 44 - 44.4 grains but it will cost you in brass life. 4 firings if you are lucky.

I agree. The calculations agree. 43 and 44.3 are the nodes. I don't know what you're disputing.

 

[Deleted member 113831]

I agree. The calculations agree. 43 and 44.3 are the nodes. I don't know what you're disputing.

Acoording to you, 45 grains is a scatter node. 44.3 is down 1.5% and it is an accuracy node. But going down another 1.5% gets you into another common accuracy node, so the pattern doesn't play out according to what you are saying.

 

[Brentc]

You're still arguing a moot point. The predicted nodes are correct on the paper.