Help interpreting OCW

[JMGlasgow]

I shot this OCW this morning. The barrel had 50 rounds through it (new barrel) before proceeding with this test. It's a 6.5 Creedmoor Criterion chromoly Remington prefit 24" 1-8" twist varmint profile.

I'm not sure that barrel specs matter but they might be helpful.

Results I see would indicate that 41.1 would be my OCW.

41.7 looks awesome but I was seeing very slight pressure signs, and temperatures today were in the 50's with a cold wind.

I don't have any velocity numbers, but my old barrel (23" Criterion SS) was 2752fps avg. with 41gr of RL16.

So what do you all think?

 

[XL Mammal]

I only look at vertical dispersion, so 40.5 if you don't want to deal with a hot load. If you can repeat that with a 5-shot group with that charge, I'd call it good and move on. Why did you settle on 41.1?

 

[Ranger188]

Theirs 2 schools of thought. Some top BR shooters like your 41.1 as it might be good, you need to adjust the seating
.02 closer to the lands and away from the lands and see if it tightens up the group.
The 41.7 if it's to hot, then don't use it. The 40.5 does have less vertical. Load 3 @ 40.4 and 40.6
and see if it does anything to the size of the groups. If not, then adjust the bullet depth .02
closer to the lands and away from the lands and see what this does
Adjusting the bullet depth makes smaller changes than powder weight changes.
You should find a good group with one of these changes.
Everyone whats to go fast. Accuracy trumps speed.

 

[Lunchbox27]

40.6 is what I run. I too hit pressure above 41.6. Im also 20” off the lands.

 

[JMGlasgow]

I only look at vertical dispersion, so 40.5 if you don't want to deal with a hot load. If you can repeat that with a 5-shot group with that charge, I'd call it good and move on. Why did you settle on 41.1?

Dan Newberry said to not dwell on group size, but where POI stays the same between 3 groups.

So, 40.8 and 41.4 both trend to the right of the aiming point, and 41.1 is between them so that's where I got my conclusion. I could be way off too. I don't see a clear result so that's why I'm asking. Maybe I'm missing something.

Speed isn't everything, but I would like to hopefully stay at above 2700 with 140's. I am contemplating a switch to 130's after I run out of 140's.

 

[Doom]

Looks like you have two nodes 40.5 and 41.7. I would recommed 40.5 and work with seaking depth to try and tighten it up. I would actually call 41.1 a scatter node.

I would only move my seating depths a couple of thousandths in either direction.

 

[JMGlasgow]

I'll work on the 40.5 and see how it goes. Hopefully velocity is adequate. I may do the whole process again if 40.5 doesn't work out.

 

[Ranger188]

If it doesn't work out, do it again, but this time
try doing a ten shot test but your only going to do 8
Since you want a faster load, start at 40.2 and load one round, load the next at
40.4 and the next at 40.6 and so on up to 41.6. You'll be short of the hot load at 41.7 So your loading one round every .2 difference
Load them all at the same bullet depth, your only changing the powder weight.
Post your results and should see a flat spot and that should be your node or nodes.
You have to be very careful in your reloading skills to get this right.
Just a different way of checking for a node.

 

[JMGlasgow]

I've done the Saterlee 10 shot method over a chronograph with my last barrel. That's where I found a node at 41gr, but it seemed very sensitive to +- on the powder charge. So with this new barrel I wanted to try OCW and see if I could get a more stable load.

 

[Ranger188]

Theirs nothing wrong with either. I sometimes shoot a 20 shot test just to see if I have a wider node to test
Sometimes you find one and sometimes you don't.
I do like to have a load thats close to 90%+ fill, they just seem to shoot better.

 

[Doom]

I think the best best load development method is the one that works best for you. They all have merits and they all have limitations.

I am a proponent of Newberry's OCW method and its worked well for me. I looked at Scott Saterlee's method I think the theory has merit but shooting only one round at each charge weight may statistically give some significant errors, particularly when using larger load increments. It can show flat spots where you actually have loads with a large Extreme spread in velocity where one load may be on the high side and the next on the low side. One benefit of the method is it takes the shooter out of the equation. I have the same issue with the traditional ladder test.

The OCW method on the other hand should work out better because it reduces the potential effects of velocity variations since three rounds are used at each load. Unfortunately, some days the shooter variation can play havoc with the test! Shoulda had DECAF!

 

[Ranger188]

The 10 shot test doesn't alway work. I've found the "flat spot" and loaded it and on either side of it
and it, and was out of node. When it does work, it takes less rounds to find what your looking for
You can always load 3 rounds and do it that way and you will eventually find your load, sometimes
takes a little longer but it always works. I now load 4 rounds, when you load 3 and one goes away
then you only have 2 to work with. With 4 you have 1 goes to the moon and you still have 3 to see
whats going on. Just me.