Seat depth test results interpretation

[Deleted noremaximus]

Good morning, I finished conducting the seat depth test for a 6.5 creedmoor 140gr rdf bullet. I already determined the powder charge. What do you guys thing of the seat depth test results. I'm not too fond. I started 15 thou off jam with 3 thou increments. This was at 100 yards 54 degree temp, sunny. Thank you.

 

[RED 7]

Given the information...I would try .001 each side of .015 jump. However, I have never had any luck with RDF bullets personally. I tried them in 6mm and 6.5mm in at least four rifles and the results were always erratic.
try 2 or 3 other bullets if you have them. Good luck.

 

[INShooter]

Try going into the lands .003 at a time. Your .000 group looks best to me.

 

[Deleted noremaximus]

Thanks guys, I agree with RDF bullets not performing well. Another fellow shooter could not get the bullets to group well. So keep them at .000. Thanks again. I have a few more bullets to go before I use them up.

 

[caihlen]

I would say set them in .003 at a time. Maybe they like to be jammed.

 

[Deleted noremaximus]

I would say set them in .003 at a time. Maybe they like to be jammed.

that would be my next test. Thanks.

 

[PopCharlie]

These groups look like mine before I got a handle on neck tension. How is your neck tension?

PopCharlie

 

[Deleted noremaximus]

I'm working on it. neck tension falls within 1-2 thousands.

 

[chkunz]

One, three-shot test group for each condition?
I think you need to redesign the test.

Start with a load you have a lot of experience with, not necessarily your best load but a good one with a lot of experience. This is your "control". Shoot a ten shot group with the control. Then guess at the right answer for your test and shoot a ten shot group with this best guess. Then shoot a ten shot group on either side of you best guess followed by another ten shot control.

Now you have sufficient data to make the next iteration if needed.

 

[Deleted noremaximus]

In what way Chkunz? What would I need to change?

 

[Deleted noremaximus]

Anyone that has shot the 140 RDF bullets, does this look normal? Or is something off in my brass prep? Thanks.

 

[Deleted noremaximus]

One process that I'm not doing is sorting bullets. Would not sorting bullets produce these results?

 

[Bill Norris]

Would definitely try .003 per load moving into the lands maybe 4 or 5 different loads and as SPJ said increase tension a tad.

 

[Richard Coody]

Lots of unknown variables here but just.looking at you test obviously into the lands is the direction to go. Don't think you have found your charge weight. After finding a seating depth you should run another charge weight test at smaller increments.

Another path is the berger seating depth test. Sometimes there are surprises out there.

 

[Deleted noremaximus]

A bit more information. Based on OCW optimal charge is 39.7gr. Any thoughts? So next step seat towards jam? How far do you guys suggest? Don't want to be close to jam point.

 

[Deleted noremaximus]

Also, all shots on the OCW test was 15 thousands off jam.

 

[caihlen]

So. In my limited experience vertical is a function of velocity. Horizontal is a function of seating depth. Looks to me like if you solve for your seating depth you can then maybe fine tune the vertical.

 

[Deleted noremaximus]

Okay, ill try going towards jam for 6 thousands. Not comfortable going any further. I'll post picks on how it went.

 

[PopCharlie]

I'm working on it. neck tension falls within 1-2 thousands.

.002 should be good, if it is consistent.

PopCharlie

 

[chkunz]

One, three-shot test group for each condition?
I think you need to redesign the test.

Start with a load you have a lot of experience with, not necessarily your best load but a good one with a lot of experience. This is your "control". Shoot a ten shot group with the control. Then guess at the right answer for your test and shoot a ten shot group with this best guess. Then shoot a ten shot group on either side of you best guess followed by another ten shot control.

Now you have sufficient data to make the next iteration if needed.

In what way Chkunz? What would I need to change?

What I am trying to say in a nice way is that at this point your data is not worth much.

Start over with a test plan that will give meaningful results. I gave you an example of a test plan that involves five ten shot groups and will probably require at least one follow up test. Some will say that is a lot of rounds but you just conducted a 24 shot test that is worthless.

Mother Nature is a bitch and it takes a statistically significant set of data to draw a reasonable conclusion.

Best wishes and thanks for sharing data. Opinions are cheep but data is valuable.