OCW Testing - Vertical Stringing

[Allen One1]

Ok I have left you hanging long enough, today I got out and shot an expanded test, attached is the picture of the target along with velocity and SD listed. I messed up on the 42.8 loads and only managed to capture 1 velocity reading. The OCW is shot without the magnetospeed and the velocity shot with the magnetospeed of course. 100 yards, 45 degrees, light wind from my back. I know Varmint you can tell at 100 yards but that is where I'm at.

 

[JFrank]

They look very similar too your previous set of targets posted. Regardless of the repeating vertical the basic idea is to have all your rounds hitting in the same area.
Tune for consistency not for small plus a pesky flyer. So with that in mind with charge gives you repeatably results.

 

[Allen One1]

For now I have went with 42.9 grn, velocity is right at 2800 and it is shooting fairly small groups. Tested at .010, .020 and .030 off the lands with .010 shooting the tightest group and .030 pretty close behind. Match next Saturday so we will see if I can hold my own.

 

[Allen One1]

Tune for consistency not for small plus a pesky flyer.

I really think this is the key so many times you see a nice group with one "flyer". I think the flyer is telling you that you are not tuned properly. A flyer is an extreme outlier you shouldn't be seeing one in every 5 shot group.

 

[Varminterror]

@Allen One1 - here’s a side by side analysis of your targets via all 3 OCW, Ladder, and Satterlee methods.

By OCW, it’s difficult to decide what should be a node - it’s simply too flat to see a real deflection between the first ~5-6 charge weights. Personally, I’d pick a node to focus on between 42.2 and 42.6 where the loads are directionally consistent but not at a high or low, and without an inflection. But in this poorly resolved short range test, it appears anything between 42.0 and 42.8 should be forgiving - or pairing at 42.8-43.0, with a high consequence of going over 43.0. I’d run another test here at the lower end, if this were the only data I had in hand.



Overlaying all of these impacts onto the same POA, for those who favor the visual comparison Ladder method, Again, it’s difficult to define the node(s), as it’s difficult to determine whether shot positions are shooter induced or truly due to the harmonic at this short range, and the relative group sizes are much bigger than the vertical dispersion between adjacent groups. Equally, any group missing its randomly fired statistical high or low would have a significant influence on the analytical result. We can see the node is NOT at the upper end, but multiple triplets of charge weights look equally viable at the low end. Not definitive, but maybe directional enough to warrant higher round count tests at the low range.



Ignoring points of impact and analyzing only velocity, the node appears very clearly between 42.2-42.6, with another less stable node at 43.0-43.2. Considering the short range of the POI test and the fact you fired the velocity test separately from the POI test, I’m not surprised to see a disparity between the results - but I’m also very much not surprised to see a very clear result from the Satterlee test with relatively non-descript results from the 100yrd POI test.

 

[Allen One1]

@Varminterror You put some serious time and thought into this, thank you. I'm reading it similar to what you are pointing out, my second choice was working with the 42.4 grn area as it appeared to be very accurate and the velocity flattened out there as well, it may well be the spot I end up.

But at the same time I wanted to see if I could push the velocity envelope to the next node. Anything over 43 grn seemed to be falling apart so that was out. Between 42.8 and 43.0 the POI is closer than anywhere else with the groups being almost right on top of each other in your overlay (which is very cool). I keep hearing everyone talk about POI being more important than velocity so I decided to try that area first.

41.9 is giving me a SD of 9.5/9.9 and ES of 25/22 with velocity of 2799/2804 (Two strings of 5 shots each). I would like to see a little better SD numbers but this isn't fire formed brass so I'm hoping I can tighten it up going forward.

 

[Varminterror]

Takes me about 2 minutes to produce the OCW photo, less than 10min to make the Ladder overlay, and less than 3min to make the excel file. I’ve spent more time typing on my in your thread to explain these things than it took to create the graphics. I make these often for folks I mentor or instruct in reloading.

Based on your results this far, I would not load at 41.9. Both your target and your velocities suggest you are out of the nodes at 42.0. Low ES/SD only means something if you have a ton of data - aka more than 10 rounds in the string - and then only if you’re shooting in a node with forgiveness on either side.

Personally, I’d either choose a different powder, or concede that there’s almost no value to that ~100fps change from your stable low node to your unstable high node. Another powder might shrink offer a stable high node at greater speed, but forcing yourself into what looks to be an unstable node just to gain 100fps will bite you in the ass downrange. Of these options, I’d tend to simply sacrifice the extra 100fps and chalk it up to potentially gained barrel life - both from avoiding further load development round count, as well as running a little slower and a little lower pressure for the bulk of my shooting with the load. Don’t look past good data just because it doesn’t tickle your fancy.

 

[Allen One1]

Takes me about 2 minutes to produce the OCW photo, less than 10min to make the Ladder overlay, and less than 3min to make the excel file. I’ve spent more time typing on my in your thread to explain these things than it took to create the graphics. I make these often for folks I mentor or instruct in reloading.

Based on your results this far, I would not load at 41.9. Both your target and your velocities suggest you are out of the nodes at 42.0. Low ES/SD only means something if you have a ton of data - aka more than 10 rounds in the string - and then only if you’re shooting in a node with forgiveness on either side.

Personally, I’d either choose a different powder, or concede that there’s almost no value to that ~100fps change from your stable low node to your unstable high node. Another powder might shrink offer a stable high node at greater speed, but forcing yourself into what looks to be an unstable node just to gain 100fps will bite you in the ass downrange. Of these options, I’d tend to simply sacrifice the extra 100fps and chalk it up to potentially gained barrel life - both from avoiding further load development round count, as well as running a little slower and a little lower pressure for the bulk of my shooting with the load. Don’t look past good data just because it doesn’t tickle your fancy.

Excellent advice and I think at this point I'm going to take it. Thank you!

 

[JFrank]

For now I have went with 42.9 grn, velocity is right at 2800 and it is shooting fairly small groups. Tested at .010, .020 and .030 off the lands with .010 shooting the tightest group and .030 pretty close behind. Match next Saturday so we will see if I can hold my own.

Sounds like a plan, a little vertical might be acceptable to stay tight.
As long as you don’t break out you should you fine.

 

[Varminterror]

I keep hearing everyone talk about POI being more important than velocity

It won’t be at long range. Seeing 30fps between 42.8 and 43.0, loading at 42.9 with gear capable of +/-0.1grn means you’ll risk ~6” of extra vertical stringing at 1,000 yards.

If you’re only playing with short range shooting, then long range load development methods we’ve been discussing aren’t of use.

So we’re back into the same trap I warned of in the first page - three shot groups at short range are too vulnerable to mechanical errors, and don’t sufficiently compare the actual ballistic performance of the respective rounds. A guy gets caught up on a tiny group or a small vertical shift, but when we have a half dozen groups 1/2”-3/4” in size whose centers all land within ~1/4”-1/3” just doesn’t tell us anything of value. If those were 5 shot groups, or single shots (as in a ladder test), the analysis results could be completely different. Take out one dot of each color on my overlay above, how much does it shift everything around? Adding the Satterlee results is a means to improve the validity of a 100 yard test, but appropriate value must be given to the velocity in that case - aka, it can’t be ignored. So my bet would be 42.9 will give a lot of extra vertical at 600-1000 than 42.4.

 

[Allen One1]

It won’t be at long range. Seeing 30fps between 42.8 and 43.0, loading at 42.9 with gear capable of +/-0.1grn means you’ll risk ~6” of extra vertical stringing at 1,000 yards.

If you’re only playing with short range shooting, then long range load development methods we’ve been discussing aren’t of use.

So we’re back into the same trap I warned of in the first page - three shot groups at short range are too vulnerable to mechanical errors, and don’t sufficiently compare the actual ballistic performance of the respective rounds. A guy gets caught up on a tiny group or a small vertical shift, but when we have a half dozen groups 1/2”-3/4” in size whose centers all land within ~1/4”-1/3” just doesn’t tell us anything of value. If those were 5 shot groups, or single shots (as in a ladder test), the analysis results could be completely different. Take out one dot of each color on my overlay above, how much does it shift everything around? Adding the Satterlee results is a means to improve the validity of a 100 yard test, but appropriate value must be given to the velocity in that case - aka, it can’t be ignored. So my bet would be 42.9 will give a lot of extra vertical at 600-1000 than 42.4.

And to your point almost everything I want to shoot is from 600-1250 yards.

 

[JFrank]

I currently use a 550 yard range for testing that will expose a sensitive or small window load real quick.
I don’t have much luck tuning short range then having that necessarily translate to LR , Some fellas are really good 100 yard tuners ( Eric Cortina promotes it )
I’d tune at a thousand yards if I had one near by

 

[Allen One1]

I currently use a 550 yard range for testing that will expose a sensitive or small window load real quick.
I don’t have much luck tuning short range then having that necessarily translate to LR , Some fellas are really good 100 yard tuners ( Eric Cortina promotes it )
I’d tune at a thousand yards if I had one near by

You could tune at 1000 yards but then you have a significant variable in the wind.

 

[JFrank]

You could tune at 1000 yards but then you have a significant variable in the wind.

I would test a daybreak using small groups of colored Bullets in whatever increments of charge or depth also neck tension and primer the same way.
Winds just part of the deal especially at 1 k

 

[Varminterror]

You could tune at 1000 yards but then you have a significant variable in the wind.

That’s why Ladder tests don’t concern themselves with horizontal drift, and largely focus on vertical displacement. We shoot in the best “low wind” condition we can find, and make our calls as appropriate, but the reality is simple - having truly resolved vertical at range is far better for load development than messing around with mechanical errors induced in short range tests.

After 20 years challenging these test methodologies and developing loads for hundreds of rifles, those of mine and others, I agree, as I’ve stated here multiple times, it’s significantly challenging to develop long range loads at 100 yards. Honestly, the only success I can say I have had in working up long range loads at 100 yards has been using the Satterlee method, as it simply isn’t so vulnerable to mechanical errors. I shot 600 yard ladders over a chronograph to prove out the consistency between the Satterlee and Audette methods, enough to satisfy that any differences in results were anomalous. Repeating the same correlation work at short range proves false, so even though I do shoot 100 yrd OCW tests along with my velocity data - because I have to shoot at SOMETHING - I know the 100 yard targets will lie to me about what might happen at 1,000 yards, whereas the chronograph doesn’t.

However, at this point, we’re beating a dead horse that we’ve lead to water. Short range OCW’s and Ladders don’t work reliably. Velocity curves, long range ladders and long range OCW’s do work reliably and repeatably.

 

[JFrank]

Wow
That’s a lotta typing’ I was thinking about the same things except for the insults to the short range OCW guys


Just messin bro
J

 

[Varminterror]

@South Prairie Jim - short range methods work for short range shooting, and the wizardry which that is just befuddles me. So I dipped my toe into 100/200, found it to not be my game, and have enjoyed putting air under bullets since. I could always find a load shooting under 1/2, squeezing into 2’s and 3’s, but getting to a reliable 1/10th or less load didn’t feel like science - it felt like holding my toes crossed and wearing a chicken bone around my neck and having a monk bless my brass... Even in long range benchrest, I found load development to be exhaustively exhausting - reliable and relatively scientific work to develop a load which will reach far without flying wide, and then endless continued work to pinch it down even further... so much more time spent in development of ammo, and so much less time developing as a shooter (not to be misconstrued as to say the shooters aren’t skilled). At the time, I counted myself a hunter first, focusing on field marksmanship, but also at that time, practical rifle matches were largely an LEO only affair and far spread even at that, but of late, field games are all the rage... For which, load development can be fast and simple, but as I said above:

[I find] it’s significantly challenging to develop long range loads at 100 yards.

 

[Nature Boy]

I’ve actually verified, for my own satisfaction, that I can shoot a modified OCW at 100 yards to select powder charge and have it hold up out to 600 yards.

@Varminterror did a great service in laying out your target horizontally to show how the POI changes.

I’d take 42.9 since it’s between a flat spot and do a seating depth test. It’s here where you’ll see your groups tighten up. The last step to fine tune your load is a primer test.

Once you have the variables of load, seating depth and primer resolved, then stretch out the distance to validate what you’ve determined at 100 yards. I bet you’ll be surprised

Here’s a rather lengthy thread I started on the subject
https://www.thehighroad.org/index.php?threads/rifle-load-development-methods-compared.851637/