How To Read OCW Test Results

Rommel Garcia · Wednesday at 8:49 PM

I went to the range today and shot my load using OCW. This is my very first time using this method. I'm having a hard time interpreting the results. Based on what I read online, you pick the load that has single-digit ES (FPS) velocity but others are looking for clusters that are adjacent to each other in terms of velocity. Then tune from there. Here's my load and test results. If I have to pick the best group, it would be Group # 5 since its got the lowest ES of velocity. It also has the smallest group size of 0.55". Group # 2 & 7 seems to have a low ES as well. But the problem is I cannot find a flat velocity between 3 charge weights which defeats the whole purpose of OCW. Shhould I pick Group # 5 and tune from there? Meaning, play with the seating depth and perhaps run a 3 charge weight, each having 3-shot group - 43.0, 43.2, 43.4. Is 43.2 a good node to tune from? Would love to hear from folks who have done OCW load testing.

Whytry85 · Thursday at 12:04 AM

I wouldn’t be looking for flat spots in velocity but rather POI consistencies between the charge weights for an OCW. If it were me, I’d look around the 43.2 like you said but shoot 5-15 rounds if possible to eliminate shooter error. And maybe even .1 of a grain increments to find the tuned window. Then seating depth to get the dwell time tuned to your barrels harmonics.

straightshooter1 · Thursday at 12:14 AM

Rommel Garcia said:
I went to the range today and shot my load using OCW. This is my very first time using this method. I'm having a hard time interpreting the results. Based on what I read online, you pick the load that has single-digit ES (FPS) velocity but others are looking for clusters that are adjacent to each other in terms of velocity. Then tune from there. Here's my load and test results. If I have to pick the best group, it would be Group # 5 since its got the lowest ES of velocity. It also has the smallest group size of 0.55". Group # 2 & 7 seems to have a low ES as well. But the problem is I cannot find a flat velocity between 3 charge weights which defeats the whole purpose of OCW. Shhould I pick Group # 5 and tune from there? Meaning, play with the seating depth and perhaps run a 3 charge weight, each having 3-shot group - 43.0, 43.2, 43.4. Is 43.2 a good node to tune from? Would love to hear from folks who have done OCW load testing.

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Velocity flat spots simply don't tell anything about what is a good load or not. You gotta go by what you see on your targets in the progression of your loads; best seen with several POA's along a horizontal line.

ShtrRdy · Thursday at 8:52 AM

As mentioned, an OCW test is all about center of group, (point of impact), compared to POI of the adjacent charge weight groups. I like to capture velocity when I do an OCW but it's more for informational use.

I'm having trouble looking at your groups placement and size.

I like how you used four shots at each powder charge. I like to do that too and then take the three closest shots.

If you haven't already, please watch this video on OCW:

waveslayer · Thursday at 9:00 AM

I'd fine tune loads 4-8 looks to be a node there with the POI being very similar

Rommel Garcia · Thursday at 11:24 AM

ShtrRdy said:
As mentioned, an OCW test is all about center of group, (point of impact), compared to POI of the adjacent charge weight groups. I like to capture velocity when I do an OCW but it's more for informational use.

I'm having trouble looking at your groups placement and size.

I like how you used four shots at each powder charge. I like to do that too and then take the three closest shots.

If you haven't already, please watch this video on OCW:

That’s a great video! It dumb it down for me enough to understand what I should do next.

ShtrRdy said:
As mentioned, an OCW test is all about center of group, (point of impact), compared to POI of the adjacent charge weight groups. I like to capture velocity when I do an OCW but it's more for informational use.

I'm having trouble looking at your groups placement and size.

I like how you used four shots at each powder charge. I like to do that too and then take the three closest shots.

If you haven't already, please watch this video on OCW:

Thats a great video! It sumb it down for me to understand what nodes I need to pick from my shots. In this case looks like my stable load is Groups 3,4 & 5. With these groups, I’ll load more with .1gr increments and find out the most stable, most accurate load. I’m so tempted to just stick with Group 5 and play with seating dept there

Changed · Thursday at 12:01 PM

Rommel Garcia said:
I went to the range today and shot my load using OCW. This is my very first time using this method. I'm having a hard time interpreting the results. Based on what I read online, you pick the load that has single-digit ES (FPS) velocity but others are looking for clusters that are adjacent to each other in terms of velocity. Then tune from there. Here's my load and test results. If I have to pick the best group, it would be Group # 5 since its got the lowest ES of velocity. It also has the smallest group size of 0.55". Group # 2 & 7 seems to have a low ES as well. But the problem is I cannot find a flat velocity between 3 charge weights which defeats the whole purpose of OCW. Shhould I pick Group # 5 and tune from there? Meaning, play with the seating depth and perhaps run a 3 charge weight, each having 3-shot group - 43.0, 43.2, 43.4. Is 43.2 a good node to tune from? Would love to hear from folks who have done OCW load testing.

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View attachment 8545770

View attachment 8545772

Despite your data, we do not have enough information to make a qualified suggestion.

What distance are you shooting these targets?
How many rounds are on the barrel?
What components are you using?
How are you loading the ammunition?
How long have you been shooting?

Rommel Garcia · Thursday at 1:56 PM

What distance are you shooting these targets? 100 yards
How many rounds are on the barrel? About 150
What components are you using? Barnes 168gr TTSX, Hornady Case, Rem 9 1/2 Primer LR, H4831SC
How are you loading the ammunition? Sing stage oresss Corstwr coax, bulleted seated .050” off the lands
How long have you been shooting? 10 years

ShtrRdy · Thursday at 9:06 PM

Rommel Garcia said:
That’s a great video! It dumb it down for me enough to understand what I should do next.

Thats a great video! It sumb it down for me to understand what nodes I need to pick from my shots. In this case looks like my stable load is Groups 3,4 & 5. With these groups, I’ll load more with .1gr increments and find out the most stable, most accurate load. I’m so tempted to just stick with Group 5 and play with seating dept there

If I'm looking at the targets correctly, isn't group #6 large? Whereas group 5 is small? If so, then group 5 is like the one in Ryan's example where he says "don't get emotional and pick that one". That's because the group from the next step in powder charge blows up.

Rommel Garcia · Thursday at 9:13 PM

Yes Group 6 blew up. That makes sense. I’m considering my node to be group 4. I’ll load up charges in increments of 0.1gr frol 42.6 till 43.2 which equates to 3 groups and total of at least 9 bullets (might go to 12 just in case i pull any).

Whatever yields the best grouping, then I’ll follow up to fine tune it by adjusting the seating depth in increments of 0.010 (+/-).

Please let me know if there’s a better approach. This is my first time playing with OCW.

Whytry85 · Thursday at 9:15 PM

Rommel Garcia said:
That’s a great video! It dumb it down for me enough to understand what I should do next.

Thats a great video! It sumb it down for me to understand what nodes I need to pick from my shots. In this case looks like my stable load is Groups 3,4 & 5. With these groups, I’ll load more with .1gr increments and find out the most stable, most accurate load. I’m so tempted to just stick with Group 5 and play with seating dept there

I mean, experiment away if learning is truly what you’re after. It might be good or it may be complete garbage. I would trust but verify though. Knowing I have a window to work within gives me peace of mind instead of one single load that does well.

Rommel Garcia · Thursday at 9:17 PM

Whytry85 said:
I mean, experiment away if learning is truly what you’re after. It might be good or it may be complete garbage. I would trust but verify though. Knowing I have a window to work within gives me peace of mind instead of one single load that does well.

Yeah at this point I know my window. Group 4 is my node. I’ll fine tune from there. I’ll soon figure out if .1gr increments really matter for my gun. It’s a hunting rifle so I’d like to make sure it’s as accurate as possible. Not banging steel on this one.

Changed · Friday at 11:01 AM

Rommel Garcia said:
What distance are you shooting these targets? 100 yards
How many rounds are on the barrel? About 150
What components are you using? Barnes 168gr TTSX, Hornady Case, Rem 9 1/2 Primer LR, H4831SC
How are you loading the ammunition? Sing stage oresss Corstwr coax, bulleted seated .050” off the lands
How long have you been shooting? 10 years

Those groups are too large to make any decision. That means it's either the bullet, gun, or your shooting ability.

I would try another bullet, as it is the easiest to test.

In your situation, I would probably pick a safe load and run the snot out of it.

Rommel Garcia · Friday at 11:31 AM

Changed said:
Those groups are too large to make any decision. That means it's either the bullet, gun, or your shooting ability.

I would try another bullet, as it is the easiest to test.

In your situation, I would probably pick a safe load and run the snot out of it.

Wouldn’t that defeat the purpose of OCW? The POI for groups 3-5 are relatively the same and grpup 6 is the scatter node which means that my OVW node is in between groups 3-5. OCW is not looking for grouping. Once the node is identified, fine tune frol there.

Changed · Friday at 12:11 PM

Rommel Garcia said:
Wouldn’t that defeat the purpose of OCW? The POI for groups 3-5 are relatively the same and grpup 6 is the scatter node which means that my OVW node is in between groups 3-5. OCW is not looking for grouping. Once the node is identified, fine tune frol there.

Your targets for 4, 5, and 6 span just over half a grain. Why is it that your groups are so vastly different. Why is it that your group 5 is so much smaller. Your target lacks consistency.

My target below spans 0.4 grains. All of those groups are extremely consistent. All are better than half MOA, and all are pretty much in the same area on the target. This is straight out of the gate, 0.010 off the lands. Berger Bullets, Lapua Brass, VV powder. All five shot groups.

My point is you need to be able to shoot consistent groups in order to make decisions. Dan Newberry clearly states that you need to be capable of shooting consistent groups. If you can regularly shoot sub half MOA, then it has to be an issue with the Bullet, or the Rifle.

The theoretical goal of the OCW first run is to find groups that are in similar areas. Like below, all of my groups are at the 4:00 position of the target.

Doom · Friday at 12:57 PM

Don't. take this too hard but my comments are based on experience. The groups do show a lot of variance in size that can't be explained by the load. Either the rifle or the shooter and usually it's the shooter if everything is tight on the rifle. I am also assuming this is a fairly light rifle, 7-1/2 lb range. Looking at the Groups themselves it appears that groups 1,2 and 3 show some consistency which tells be the rifle and shooter have some consistency here. I would pick a load between 1 and 2 for now and get some experience with the rifle with these lower recoiling rounds. In particular work on shooting 3 or 5 shot groups (not round robin) that have consistent average POI. Work on managing consistency in recoil and maintaining solid fundamentals. Leave the chronograph at home. It doesn't help with shooting skills.

Slayor · Friday at 5:01 PM

Group # 5 does seem like a solid choice since it has the lowest ES and the smallest group size. Even though you’re not seeing a flat velocity across the charge weights, it’s common to encounter that in the initial stages of tuning. Starting with Group # 5 and then adjusting the seating depth is a great plan. Running a 3-shot group for the charge weights of 43.0, 43.2, and 43.4 is a smart way to refine your load. Since 43.2 appears to be a good node, it makes sense to focus on that and see how it performs. Keep an eye on both the velocity consistency and group size as you tweak those variables.
Good luck and I hope you get some great results!

Csafisher · Saturday at 12:05 AM

Rommel Garcia said:
Wouldn’t that defeat the purpose of OCW? The POI for groups 3-5 are relatively the same and grpup 6 is the scatter node which means that my OVW node is in between groups 3-5. OCW is not looking for grouping. Once the node is identified, fine tune frol there.

Re-shoot the test. I bet you’ll find different results…. And looking at SD and ES based on 4 shots is almost pointless. If you’re set on the powder and bullet, pick a speed and run with.

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How To Read OCW Test Results

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