OCW results. Where to go from here?

[kskevin]

I ran two OCW tests for my 223 Rem. Both used Sierra BlitzKing 55g bullets loaded to the lands, Fed 205M primers, once fired winchester brass neck sized only.

First test was with Hodgdon Benchmark with charges from 23.8 to 25.9 in 0.3g increments. I know I'm only supposed to be concerned at this point with the center of the 3 shot POI but all 8 groups are nearly identical. However, the groups did open up when I got to 25.0+ charge wts. Where would you guys go from here (I'm assuming pick a chg wt, then play with seating depth, but which chg wt?).

2nd test was with Hodgdon 8208XBR with charges from 23.5 to 25.6 in 0.3g increments. The center of POI for 23.5 thru 24.4 were pretty consistent but group sizes were much larger than with Benchmark. From 24.7 on up, the shots were all over the place (5th and 6th groups each have 1 shot on the top edge of the paper). Would you even spend any more time with this powder playing with seating depths or just give up on this bullet/powder combo?

 

[MALLARD]

Re: OCW results. Where to go from here?

24.4 & 24.7 of benchmark looks promising. I would load 24.55gr of benchmark and play with the seating depths , then once you get your seating depth results play with the powder charges again. between weights 24.3-24.8 of benchmark.

 

[turbo54]

Re: OCW results. Where to go from here?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MALLARD</div><div class="ubbcode-body">24.4 & 24.7 of benchmark looks promising. I would load 24.55gr of benchmark and play with the seating depths , then once you get your seating depth results play with the powder charges again. between weights 24.3-24.8 of benchmark. </div></div>

+1... the one on the top left looks good two. These groups don't look that identical to me.

 

[kskevin]

Re: OCW results. Where to go from here?

Can you explain a bit more in your comment about the groups not looking very similar. While I understand the do LOOK different, the change in POI was not too different from one group to the next other than going from #4->#5. My understanding of the OCW test is I am trying to find consecutive charges where the center of the groups have minimal change from one to the next and when I look at the CHANGE in POI, they don't differ by much.

Center of groups moved as follows
1-2 0.2"
2-3 0.25"
3-4 0.25"
4-5 0.6"
5-6 0.3"
6-7 0.4"
7-8 0.4"

Groups 1-4 continued to move to the right as I progressed thru each load, then groups 5&6 came back to center, 7 dropped low and then 8 jumped back up.

I'm not questioning your advice but would like to understand a bit more of your rationale in your suggestions. Thanks for the help.

 

[trailrider121]

Re: OCW results. Where to go from here?

For the benchmark load I see a scatter node at 24.1gr and an ocw charge right at 24.5gr. Looks like 24.4gr just starting to come into play and getting another scatter node at 25.0grs.

I would pick 24.5gr and adjust seating depth, then go back and test 24.3,24.5, and 24.7gr. All these should go into 1MOA easy.