Interpreting OCW Test

jpistolero02

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I broke out the trusty old AI MK III today. I came across an article talking about PRS guys having good luck with 140’s in their 6.5X47’s. I have always shot 130’s. Anyway, the rifle seems to like them. All the loads had pretty consistent SD numbers. Any suggestions on where to go from here? I would like to load a few up and try them at distance. For reference, the worst groups on the far left are still under .5”. Most of the time it’s pretty easy to read, but these all pretty much shoot in the same darn spot.
 

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Saffer

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I would look at ES and shoot a few groups at 300m,it will tell you more about your loads.
 

Culpeper

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That is just the card you picked. You're assuming the shooter has no input in the result of those groups.
 

jpistolero02

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Haha, I am certainly no expert shooter. I do appreciate you guys for providing some feedback. I will do the ladder at longer distance and see what happens.
 

Dthomas3523

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Run the test again, but with a chrono and don’t worry with groups.

Much easier to find a powder node that way. And then you can make anything you want shoot with seating depth.
 

DellaDog

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And then you can make anything you want shoot with seating depth.
I read/hear this a lot, but in practice rarely find it to be true for the bullets I use. In 223, the SMKs seem unaffected by seating depth. Likewise, any of the Berger Hybrids I shoot in 6 & 6.5 shoot pretty much the same regardless of seating depth. So much so, Bryan Litz recommends 015 as initial seating depth and just run with it till the barrel’s toast. No need to chase the lands.
 
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Dthomas3523

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I read/hear this a lot, but in practice rarely find it to be true for the bullets I use. In 223, the SMKs seem unaffected by seating depth. Likewise, any of the Berger Hybrids I shoot in 6 & 6.5 shoot pretty much the same regardless of seating depth. So much so, Bryan Litz recommends 015 as initial seating depth and just run with it till the barrel’s toast. No need to chase the lands.
I can make any Berger bullet I own change group size via seating depth. Sometimes not a lot, but it changes. 85.5, 105, 109, 130, 140’s etc.

The high level F class guys I know can do it with the berger 180’s.

If someone can’t, they are doing something wrong, or system (shooter, rifle, etc etc) isn’t capable of the accuracy to see the change.
 

Dthomas3523

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Jump has far less to do with the bullet’s “sensitivity to jump” than it does the timing the bullet leaves the barrel.

Possibly the bullets of year’s past may have. But with modern Bullets we are using seating depth to find the best timing of the bullet leaving the barrel. This is why there are several seating nodes the further you seat as it’s timing the harmonic (for lack of a better word) of the barrel as it’s moving.

We do the inverse with a barrel tuner. We change the movement of the barrel as it’s whipping to the best place for the bullet.
 

DellaDog

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If someone can’t, they are doing something wrong, or system (shooter, rifle, etc etc) isn’t capable of the accuracy to see the change.
Maybe, but I sure have tried.

I recently worked up a load (Newberry OCW) for a new 6 BRA using 105 Hybrids 015 off. Familiar with rough starting weights, I only ran it with a few grains difference start to finish. The results were pretty obvious, the plots favored 31.0 grains of Varget at 2920 fps. 31.0 gr. shot .16" (Probably coincidental the smallest group was in the center of the node.) With the Newberry method of round robin shots, I don't think it coincidental that every 5th shot of 40 landed in the same hole.

I next tried playing with seating depth changes, 003 at a time out to around 060 and remarkably I found no appreciable difference, certainly none shot smaller.

I've done this with 223 SMKs , 75 ELDMs, and 6 & 6.5 Berger Hyrbids - and always found the charge weight to produce the most significant advantage over seating depth.

I'm certainly not arguing against the theory, I just haven't found it to show in practice. The targets below represent the results of OCWs and just shooting the same seating depth (With the 223 & 6.5 until the barrels were toast).

6.png

75.jpg

140.JPG
 

918v

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Seems OP has a very broad accuracy node, but I wonder if he did it in .1gr increments would the groups shift a little?
 
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Dthomas3523

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Maybe, but I sure have tried.

I recently worked up a load (Newberry OCW) for a new 6 BRA using 105 Hybrids 015 off. Familiar with rough starting weights, I only ran it with a few grains difference start to finish. The results were pretty obvious, the plots favored 31.0 grains of Varget at 2920 fps. 31.0 gr. shot .16" (Probably coincidental the smallest group was in the center of the node.) With the Newberry method of round robin shots, I don't think it coincidental that every 5th shot of 40 landed in the same hole.

I next tried playing with seating depth changes, 003 at a time out to around 060 and remarkably I found no appreciable difference, certainly none shot smaller.

I've done this with 223 SMKs , 75 ELDMs, and 6 & 6.5 Berger Hyrbids - and always found the charge weight to produce the most significant advantage over seating depth.

I'm certainly not arguing against the theory, I just haven't found it to show in practice. The targets below represent the results of OCWs and just shooting the same seating depth (With the 223 & 6.5 until the barrels were toast).

View attachment 7363041

View attachment 7363044

View attachment 7363043
If that last pic is the seating test, there’s nodes in

.10-.30
And
.60-.80
 
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Dthomas3523

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Also, if you just use the same seating depth and adjust powder until groups look good, you are now using the powder charge to time the bullet exit.

The problem is if you’re not in a flat/good ES powder node, when temp or something else changes, your velocity change will be enough to affect the down range performance. This is one of the culprits of “my group fell apart at distance.”
 

Doom

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The OP's test is an example of an excellent rifle, fired by an excellent shooter, with a very forgiving bullet, powder and cartridge combination. Part of OCW testing is to find a forgiving charge weight at 100yds but it must be verified at distance. As to what distance, I'll leave that to the OP as he knows what he is trying to accomplish.

In response to the original question I'll explain why I think the area to look at is around 37.2 gr. I did not just pick a card. The POI centers for 36.9, 37.2 and 37.3 are almost identical. In fact, if the 3 groups were overplayed you would have an excellent 9 shot group. Typically, the group size is not of primary importance in OCW, but in the case of this rife and shooter, group size does aid in trying to find the node. Is this a node? It appears to be. To further justify looking at it further is based on the fact that the 36 gr group appears as a scatter node, assuming the shooter is as accurate on this charge as the others. That would suggest a node ~1.5% higher at ~36.5 and another at ~3% higher at 37.6 gr. If 37.2 turns south at distance then looking at the 37.6 area would be the next window.

When Dan Newberry developed his method it was before the more reliable and easier to implement chronographs such as the Lab Radar or Magnetospeed were on the market. It still works without that data. I will add though that chronograph. data in this instance sould help refine the the test. But as the OP stated even the SD's were consistent.
 
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Dthomas3523

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The OP's test is an example of an excellent rifle, fired by an excellent shooter, with a very forgiving bullet, powder and cartridge combination. Part of OCW testing is to find a forgiving charge weight at 100yds but it must be verified at distance. As to what distance, I'll leave that to the OP as he knows what he is trying to accomplish.

In response to the original question I'll explain why I think the area to look at is around 37.2 gr. I did not just pick a card. The POI centers for 36.9, 37.2 and 37.3 are almost identical. In fact, if the 3 groups were overplayed you would have an excellent 9 shot group. Typically, the group size is not of primary importance in OCW, but in the case of this rife and shooter, group size does aid in trying to find the node. Is this a node? It appears to be. To further justify looking at it further is based on the fact that the 36 gr group appears as a scatter node, assuming the shooter is as accurate on this charge as the others. That would suggest a node ~1.5% higher at ~36.5 and another at ~3% higher at 37.6 gr. If 37.2 turns south at distance then looking at the 37.6 area would be the next window.

When Dan Newberry developed his method it was before the more reliable and easier to implement chronographs such as the Lab Radar or Magnetospeed were on the market. It still works without that data. I will add though that chronograph. data in this instance sould help refine the the test. But as the OP stated even the SD's were consistent.
And this is why (no offense) I feel these types of tests are outdated. It takes this much explaining. And it requires shooting at distance.

With powder/seating tests separated, you are only looking for one thing each time and it’s readily clear what’s going on and what is better.

Then the only reason to test at distance is to make sure the bullet’s BC doesn’t vary too much from bullet to bullet which would then require sorting and/or tipping.
 

jpistolero02

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In my initial test, the most consistent numbers came from 37.2-37.5. I was having some sun/shade issues with my chronograph, so I would like to validate. Also, I was only shooting 3 shot groups for sake of speed. That's not a ton of numbers to base things off of. The group at 37.5 averaged 2832 with an ES of 6 and SD of 3. The group at 37.2 had an average of 2815 with an ES of 11 and SD of 5.
 

Dthomas3523

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In my initial test, the most consistent numbers came from 37.2-37.5. I was having some sun/shade issues with my chronograph, so I would like to validate. Also, I was only shooting 3 shot groups for sake of speed. That's not a ton of numbers to base things off of. The group at 37.5 averaged 2832 with an ES of 6 and SD of 3. The group at 37.2 had an average of 2815 with an ES of 11 and SD of 5.
Depending on your brass prep and powder drop, 3 shots can give you the confidence you need in your chrono numbers.

Most of my numbers stay about the same (5-10sd and 15-25es) over very long shot strings as they do with 3. Reason being is the consistency in my loading process.

If you aren’t monitoring your tolerances, then you’ll need a higher shot sample to be confident.

Also, ditch the optical chrono and get a magneto or Labradar. They truly do reduce load development to trivial tasks.
 
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needham

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I would load 10 rounds at 37.3 or 37.4, shoot it at 300 and if it looks good, call it a day.
 

needham

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Depending on your brass prep and powder drop, 3 shots can give you the confidence you need in your chrono numbers.

Most of my numbers stay about the same (5-10sd and 15-25es) over very long shot strings as they do with 3. Reason being is the consistency in my loading process.

If you aren’t monitoring your tolerances, then you’ll need a higher shot sample to be confident.

Also, ditch the optical chrono and get a magneto or Labradar. They truly do reduce load development to trivial tasks.

I think you are right for the folks who anneal, run honed dies, mandrels, drop powder with a fx120i, magnetospeed or better ect ect. which is exactly what it takes to run a satterlee type method, and might even have to add sort cases by water volume to that too.
but that aint the average reloading joe

I am no expert at all, however, I have always seen the point of OCW as finding a solid load (moa or better) with stock gear that will hold up with to a variety of swinging conditions.
but if a guy is gonna go supremely all out on reloading gear, the process then ladders, satterlee, etc can be quicker and possiby more effective
 

Dthomas3523

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I think you are right for the folks who anneal, run honed dies, mandrels, drop powder with a fx120i, magnetospeed or better ect ect. which is exactly what it takes to run a satterlee type method, and might even have to add sort cases by water volume to that too.
but that aint the average reloading joe

I am no expert at all, however, I have always seen the point of OCW as finding a solid load (moa or better) with stock gear that will hold up with to a variety of swinging conditions.
but if a guy is gonna go supremely all out on reloading gear, the process then ladders, satterlee, etc can be quicker and possiby more effective
Agreed except for brass sorting. Of all the things, brass sorting and primer pockets give the very least return on investment.
 

supercorndogs

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Agreed except for brass sorting. Of all the things, brass sorting and primer pockets give the very least return on investment.
I would have thought .1g of resolution would be enough to find the flat spot with a chronograph. Would you say doing load development with a chronograph using a charge master is a pipe dream?
 

Dthomas3523

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I would have thought .1g of resolution would be enough to find the flat spot with a chronograph. Would you say doing load development with a chronograph using a charge master is a pipe dream?
No. I know several F class guys that used charge masters in the past.

If you can keep your ES under 30 and SD under 15 you’re fine.

If not finding a flat spot, change primers. I’ve seen some primer/powder combos just keep increasing. And when one of the two is changed, you can find a flat spot. Since velocity is mainly from the ignition/combustion.....if you don’t have flat spots, you need to change that part up.
 
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