Just did my first OCW & I need help analyzing it

[dlouie87]

Hello,

I just did my first OCW with my new rifle and some hand loads. Is it ok to do this test at 103 yards or should I have performed this test at a further distance? I was able to gather some groups and some data from the "Shooting Chrony" but would like some help reading it.

Here is a picture and it seems to me my point of impact is just low and to the right. I'm assuming 44.2 is my accuracy node and I think I need to load some more rounds from 43.9 - 44.5 in .2gr increments.

At what distances should I perform the next test? When would I need to start messing with the seating depth?



The velocity of the groups were:

42.7 - 2670fps
43.6 - 2765 avg FPS , 14 SD
43.9 - 2786 avg fps , 15 SD, 28 ES ( 2804, 2776, 2778fps)
44.2 - 2781 avg fps, 6 SD, 14 ES --> took 4 shots ( 2785, 2773, 2780, 2787 fps)
44.5 - 2803 avg fps, 11 SD, 25 ES --> took 4 shots ( 2804, 2813, 2788, 2809fps)
44.8 - 2818 avg FPS, .5 SD, 1 ES --> took 4 shots (2819, 2818, 2819, 2819fps)
45.1 - 2816 avg FPS, 6 SD, 11 ES (Minor pressure signs by light ejector swipes on new brass) (2811, 2822, 2817)

Thank you,

DL

 

[SWThomas]

I think you computed your ES and SD wrong. There's no way the SD should be a higher number than the ES. And I'm gonna call BS on a .5 SD and a 0 ES. Sorry.

What are you shooting? Rifle and component combo?

 

[InfScout1/69]

Just looking at your targets.. I would go with 44.5 and fine tune it

 

[InfScout1/69]

Just did my first OCW & I need help analyzing it

I would fine tune from 44.2-44.7 working in . 1 grain increments

 

[dlouie87]

No need to be sorry. I would like to be corrected if I'm wrong. I just pulled the numbers off the Chrony screen and tried to calculate it up myself. I made a mistake. I just used excel to calculate it out.

The thread is updated with the new and hopefully, more correct ES numbers

I'm shooting a .308 that was built by Marc @ Spartan Rifles. It's on a Deviant action with a 24'' barrel. The rounds are loaded to 2.774 -2.775 COAL. The components are varget, wrlp, and 175 smks in winchester brass.

InfScout1/69 -- And thank you, I'll take that advice in consideration.

 

[gstaylorg]

I would revisit 44.1 to 44.6 in 0.1 gr increments, using 5-shot groups/MVs. Determine the width of the charge weight "window" that shows small groups and low ES. Your load will be in the center of that charge weight range. If you want to fine tune further, vary seating depth by .003" in something like at least two increments on either side of whatever the ones above were. I am guessing that one of these (44.3/44.4/44.5) will be dead center in the window and that you'll be very happy with the final results. Probably not much need to go higher than 44.6. Based on the velocities, those are very hot loads and the group spreads/ES values don't warrant it.

BTW - I'm guessing you mean (above) that your cartridge base-to-ogive (CBTO) is 2.275". That would be pretty short for COAL in a .308 and you wrote on the target that COAL was 2.774. In any case, I think you've got yourself a shooter. Good luck!

 

[Twoboxer]

FWIW, what troubles me is the "significant" change in POI shown by 44.2 compared to 43.9 and 44.5. It would be easy to call 44.35 as your node if the 44.2 grp were, say, 3 sqs left and if I ignore the extra shot . There would then be a wide charge range where the POI is virtually unchanged.

Were it me, in the next test (44.2-44.8) I'd be trying to find out if the best load allowing for some charge variation might be slightly under, equal, or slightly above 44.5. If a second run of 44.2 shows the same rightward tendency, I'd be thinking 44.5/44.6 is the best . If it mirrors the others and stays left this time, you have a nice wide range to pick from lol.

 

[RollinCoal11]

I like your ladder target. Mind if I ask where you got it ?

 

[Tristian19]

A1: 103 yards is fine - Perform next test at 100 yards
A2: Go to 200 plus yards when you have a node or narrowing done a node - to name a few.
A3: Once you decide on a node then, begin changing your OAL's and watch groups spread and or shrink.


I read these results as POI moving between low right and low left depending on charge - excluding four single shots.
left - right
right - left
right - left
left - right


I am trying to understand WHY 43.9 - 44.5.
Based on YOUR results, what would following shot groups look like? Use YOUR blocks to map it out

Q1: Take two shots from 43.9, 44.2 & 44.5. How many blocks would these six shots take?
Would you be happy with this group?

Q2: Take two shots from 43.6, 43.75 and 43.9? Where would 43.75 impact based on your results?
Would you be happy with this group?

Q3: Take two shots from 44.5, 44.65 and 44.8? Where would 44.75 impact based on your results?
Would you be happy with this group?

Thoughts for consideration:
- Load five shots for each load you choose next.
- Take notes of each shot as you take them noting on separate paper as you shoot so you can label each shot in order on final target.
- Shoot ALL shots in one line from left to right instead of shooting vertically.
- Watch your POI.

Not sure if above makes sense.

Just a few quick thoughts and .02 cents...

 

[dlouie87]

ofd343 - This SH member made these targets. Very useful with the grid.
http://www.snipershide.com/shooting/snipers-hide-reloading-depot/187766-ocw-targets-download.html

Twoboxer - The shift in POI may be an error made by me and inconsistency in my shooting. I'll try what you mentioned and observe if the POI hits 2 squares to the left for 44.2.

Tristian19 - It made sense and the tips will be considered.

Thank you all.

 

[RollinCoal11]

ofd343 - This SH member made these targets. Very useful with the grid.
http://www.snipershide.com/shooting/snipers-hide-reloading-depot/187766-ocw-targets-download.html

Twoboxer - The shift in POI may be an error made by me and inconsistency in my shooting. I'll try what you mentioned and observe if the POI hits 2 squares to the left for 44.2.

Tristian19 - It made sense and the tips will be considered.

Thank you all.

Thanks man..

 

[Tristian19]

Twoboxer - The shift in POI may be an error made by me and inconsistency in my shooting. I'll try what you mentioned and observe if the POI hits 2 squares to the left for 44.2.

Hey dlouie87,

Reason I suggested you consider shooting horizontal is because I have found POI to be more true than a vertical OCW. You appear to have chosen a great target for OCW. Squares help a great deal with observing and reading. I will add to my home made targets.

Thanks for sharing.

Just another .02...

Safe shooting