Help me determine OCW

[cbr9290318]

I followed the optimal charge weight procedure from Dan Newberry but am having some trouble interpreting the results. This is my first precision load work up. I need to develop a load at 300 yards or less but I hope to do a 1,000 yard clinic with this load eventually.

This is a .308 using 155 gr HPBT over Varget powder. COAL 2.78" (I'll play with it once I have my OCW).

Forgive the photos.

Based on the group centers it seems like I should focus around 43.8 and 45.8. I am curious if anyone has a better take on the results. Otherwise, I may try 0.1 gr increments around 43.8 and 45.8 and/or pushing thr distance out to 300 yards (which is my max range length).

Appreciate any feedback.

Sent from my SM-N960U using Tapatalk

[TimRB]

Looks like a sweet spot from 45.0 to 45.6. I'd probably settle on 45.3 and call it a day.

Edit: You really need to be shooting far more than three shots, though. Most people will shoot five, which also isn't really enough. Try ten.

Tim

[racinjason233]

I would work right around 45.0 and move the elevation knob 2 clicks and windage 4 clicks. Put all 5 rounds in the red X then move out another 100 yards.

[smoothy8500]

Newberry's OCW can be difficult to interpret: Measuring group sizes and distances and directions from the bullseye, you will know which three groups come the closest to hitting the target in the same POI. Sounds like you are trying to focus on the horizontal distance too.

I would consider 43.8 the "scatter node" due to the vertical dispersion compared to the other loads.

At 45.3 through 46.2 you see the POI has jumped up half an inch but stays fairly stable, with minimal vertical dispersion. Generally, the OCW is around 1.0gr wide, as in this case. I do my OCW tests at 300yds looking for stable vertical dispersion.

[cbr9290318]

Looks like a sweet spot from 45.0 to 45.6. I'd probably settle on 45.3 and call it a day.

Edit: You really need to be shooting far more than three shots, though. Most people will shoot five, which also isn't really enough. Try ten.

Tim

Thanks, I plan to shoot larger groups once I narrow my loads down a bit for further development.

Sent from my SM-N960U using Tapatalk

[cbr9290318]

Newberry's OCW can be difficult to interpret: Measuring group sizes and distances and directions from the bullseye, you will know which three groups come the closest to hitting the target in the same POI. Sounds like you are trying to focus on the horizontal distance too.



I would consider 43.8 the "scatter node" due to the vertical dispersion compared to the other loads.



At 45.3 through 46.2 you see the POI has jumped up half an inch but stays fairly stable, with minimal vertical dispersion. Generally, the OCW is around 1.0gr wide, as in this case. I do my OCW tests at 300yds looking for stable vertical dispersion.

Thank you.. I get that vertical dispersion is probably more important but it is confusing and Newberry appears to suggest to look at the center of group location including horizontal for consistency. As you suggest, I may work in the 45.3 to 46.2 range and see if I get similar results, maybe pushing out to 200.

Sent from my SM-N960U using Tapatalk

[choprzrul]

I'd be interested in seeing your velocities for the above targets along with standard deviation for each group.

.

[cbr9290318]

I'd be interested in seeing your velocities for the above targets along with standard deviation for each group.

.

I'll post them up. Unfortunately I got a bunch of errors so the results were not conclusive. I was seeing some speed nodes in my first round robin but in then started getting errors. I think the light conditions changed and it got too dark.

[cbr9290318]

I'd be interested in seeing your velocities for the above targets along with standard deviation for each group.

.

Here are the numbers. I spaced shots out by about 2 minutes and temperature was 55 degrees. I assume the velocity increase from the 1st to 2nd string is due to raised barrel temperature.



Sent from my SM-N960U using Tapatalk

[smoothy8500]

I was seeing some speed nodes in my first round robin but then started getting errors.

The beauty of Newberry's OCW is that ES/SD's aren't really as important.