6.5 OCW Test

[jpmimproved]

So I finally broke down and bought myself some H4350, sworn by everyone that it is THE powder for the short action 6.5's. Doing the OCW test, I had probably the most positive, easy to read results I've ever had doing the test, so thought I might share my results. Started at 40.8 Gr with 130 VLDs, went up .3 gr per group. I brought my zero up .3 MIL so as to not affect my aiming point.


(Note that the target on the right is offset about 1/4" lower than the left)



What I noticed most was that right as I approached what I would call the beginning of a scatter node (41.7, 43.5) also had the least amount of vertical dispersion. To my eye, the low vertical dispersion in conjunction with the similar amount of difference in displacement at the 42.9-43.2 leads me to think that 43.1 is a great place to start.

 

[Clucknmoan]

Interested in this one and to see what everyone thinks. I don't have nearly the experience decifering these as most on here. So please educate me if I'm off.

To me it looks like 43.2 made a pretty large shift left and then 43.5 shifted back right again. I wouldn't think that would be very stable.

What about 42.6 to 42.9? That seems to have the same POI on paper.

 

[jpmimproved]

My thought is that 42.6 and 42.9 may be in the lower end of the node. When doing the OCW test, I try not to pay attention to horizontal, as my understanding is that you "tune out" the horizontal dispersion using seating depth and primer testing. I am by no means an expert, but this method has made load development much less of guesswork and more scientific.

 

[Clucknmoan]

Could be wrong but I look for POI shift or better yet lack of shift on an OCW, not necessarily vertical or horizontal. I just use the ladder to look for vertical. Staying tuned to see how this turns out.

 

[Cowtownup]

I like to shoot at the center of the circles. I understand why you didn’t, but with only 3 shots you are not going to destroy the center where you can’t get back to POA. Plus it helps to have a reference to look for POI shift on an OCW test.. However, I think 42.6, 42.9 and 43.2 have the most similar POI. Good luck..

 

[Depart123]

There are a couple of things happening at once. When you reach 42.3g you are coming into your optimal pressure range, indicated by the fact that your average POI stops increasing. As you noted, you are coming out of a scatter node. The barrel harmonic is transitioning from a mostly vertical dispersion to a horizontal one. The groups go from a relatively vertical dispersion, to a round shape, then go mostly horizontal. This transition is complete at 42.9g.

I have seen this same pattern in many barrels. If it were me, I would start shooting 10 shot groups at 42.9g and on. Keep in mind the powder temps you are experiencing on that day and when you find a node that gives good SD, try to account for summer heat that will be raising pressures in a few months. Once that is nailed down, then fine tune with seating depth.

Theoretically, If you didn't find a node with good SD from 42.9g on, then this powder bullet combo would not be considered optimal. I don't see that happening though, H4350 and the smaller 6.5's is a well proven combo.

 

[daniel brothers]

If it were me... I'd load up a bunch more with 43.4 and re-test with different seating depths. Once you get a more defined seating depth, then you can compare both the powder and seating to make a more accurate evaluation. After comparing those two test together... then you could even load a bunch more up with that same powder... the best seating depth... and then ONLY change up the primers. You should have a winner after comparing those three test together. Then.... take her out LONG and let her stretch her legs.

 

[josh shrum]

Looks like you are into a good spot from 42.9 on. I would load up 10 @ each charge (42.9, 43.2 43.5) and see how they group. If you can chrono them you should be able to adjust your powder charges for changing temps to stay in a good spot. Once you find the best charge weight work your seating depth, your set up seems to be showing a lot of promise.

If you can test over wind flags even better, no need to get fancy, a few poles with surveyors tape is all you need to shoot in a repeating condition.

Josh

 

[Clucknmoan]

This is an eye opener for me and the OCW. I never paid a whole lot of attention to the vertical spread on one, just POI shifts. Hopefully the OP keeps on with updates, I'd like to see how it turns out.

 

[USMCDOC]

I would now do a OCW with 42.7 to 43.1 in one tenth increments..

 

[jpmimproved]

Finally got around to the seating depth test.

Ran 4 shots of 43.1 gr at each seating depth(.020” to .050” w/ .005” increments. Looks like .025” to .030” off may be a winner

 

[Bart B.]

I'd like to see the same test using 10 shot groups for each load.

 

[jpmimproved]

I like 10 round groups too, but not interested in burning 80 rounds for the test. I’ll probably shoot a 10 short group just to make sure that I’m happy with my chose load and seating depth, but I’m fairly confident that it will meet my needs.

 

[10ring1]

Lookin good brother. No pressure signs up on the higher end of your loads? Just asking, did u chrono these? Are these results as valid without Es/Sd?