OCW Test Results - 6mm ARC, 105 Hybrids, Varget

[SMTGWKD]

Shot this OCW this week and thought I'd share both for info to other ARC shooters and for input reading the OCW. I accidentally cut out the 26.8 and 27.0 groups 1 inch higher than the others, but this should still be easy to interpret poa vs poi.

I've been reading up a bunch on this and am wondering what you would do next after this OCW to balance wasting components vs "good enough".

Would you just load up at 26.8 grains and go ring steel at this point? Or keep refining?

Appreciate your insight!

 

[ShtrRdy]

For an OCW test I like to look for where the groups have similar point of impact, POI. In your case that would be 26.4 & 26.6.

I'm not familiar with the ARK but can you expect to get more velocity out of that cartridge?

What type of chrono were you using? If it was a Magnetospeed then your group size and POI can be influenced.

 

[SMTGWKD]

Labradar was used. This is the top end of load data for velocity with Varget.

The thing that's interesting to me in Dan Newberry's dialogue in the following video is his comments regarding crescent groups before nodes and scatter groups +/- 1.5%.



Given this logic, if I assume that 27.0 is a scatter group, I should find a node at 26.6 grains. If I plot center of each group, the 26.6-26.8 is the closest POI - but 26.4 isn't far off.

What would you do for next steps?

 

[ShtrRdy]

I guess I'm misunderstanding the shift on the targets between 26.6 and 26.8. I realize you mentioned having a different aim point.

 

[waveslayer]

Best advice, and I see this all the time. Hard to tell because we can't see your POA... other wise we can't see your nodes easily. I always cut out my targets but I include the POA. You can even map them on a blank piece of paper to see the nodes.

 

[BuildingConceptsllc]

I also did a OCW test with my 6cm. This is what mine looks like.

1- 41.9
2-42.2
3-42.5
4-42.8
5-43.1(this is my load)
6-43.4
7-43.7

I pulled what was the 4th shot because it was dark by the time I got there and only had 4 for each in case I pulled one. I already had it marked for which shot was which so I went ahead and shot the 4th even though it was dark so, disregard the obvious pulled shot.
Have to have a central point of aim for this to work correctly.

 

[BuildingConceptsllc]

Now I will tune with seating depth until it's one hole.

 

[BuildingConceptsllc]

Labradar was used. This is the top end of load data for velocity with Varget.

The thing that's interesting to me in Dan Newberry's dialogue in the following video is his comments regarding crescent groups before nodes and scatter groups +/- 1.5%.



Given this logic, if I assume that 27.0 is a scatter group, I should find a node at 26.6 grains. If I plot center of each group, the 26.6-26.8 is the closest POI - but 26.4 isn't far off.

What would you do for next steps?

Load 26.7gr and do a seating test if that's what you want to go with but it's hard to really tell with that target

 

[SMTGWKD]

Gents - identical point of aim for each target. I just accidentally cut them out one inch differently on a couple so you can't see the original POA but the grids are identical. Really easy to see in the targets - just look at the position of the groups relative to the grid as the POA was identical relative to the groups.

In short - the triangulated center POI for 26.4-26.8 are nearly identical.

 

[waveslayer]

Ok, 26.5 is your powder charge, now do seating depth to fine tune it. Off to the races