Seat depth test results interpretation

[urbanrifleman]

I think one set of groups means nothing. Any test that is reasonably conclusive will go through at least twice. At least.

 

[Deleted noremaximus]

I think one set of groups means nothing. Any test that is reasonably conclusive will go through at least twice. At least.

I understand, thank you.

 

[taylorw]

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.

I tried this same bullet in the same cartridge and started jumping farther when I couldn’t find anything between +15K through -30K. It ended up shooting ok at around -70K. If you started at 15k off jam and worked back another 20K, I’d say your around -10K off the lands now. Try going backwards in 10K increments (3shot groups to save on components) until you hit -90K. You can jump over seating nodes in these large changes but it can give you an idea of where to start also, when you don’t have a good idea. Sounds like a ridiculous jump but some these bullets are working around that -50 through -90 mark. If you have other bullets to test, you may be better off to stop with this one. I eventually ended up running only 130VLD’s in the 6.5 Creedmoor. Good luck!

 

[Deleted noremaximus]

I tried this same bullet in the same cartridge and started jumping farther when I couldn’t find anything between +15K through -30K. It ended up shooting ok at around -70K. If you started at 15k off jam and worked back another 20K, I’d say your around -10K off the lands now. Try going backwards in 10K increments (3shot groups to save on components) until you hit -90K. You can jump over seating nodes in these large changes but it can give you an idea of where to start also, when you don’t have a good idea. Sounds like a ridiculous jump but some these bullets are working around that -50 through -90 mark. If you have other bullets to test, you may be better off to stop with this one. I eventually ended up running only 130VLD’s in the 6.5 Creedmoor. Good luck!

Thank you, I'm hearing that the overall consensus is that 140 RDF bullets are pretty bad.

 

[JFrank]

Nosler has put a lot of time and resources towards them claiming insensitive to jumping

 

[urbanrifleman]

Did you do a load workup with a Berger first?

 

[JFrank]

This may be relevant as well.

 

[LCazador]

can someone provide some insight on my brass prep. I'm a F-class beginner.
New Lapua Brass
Fire Form Brass
FL size without neck collet.
Run Brass through K&M Mandrel for neck turning
Neck turn the brass
Tumble Brass
Run brass trough 1.5 thousand K&M mandrel for neck tension
brush necks twice with brass brush
Clean primer pocket
Ready for load.

Once fired brass.
Anneal Brass
FL Size without Neck collet
Run Brass through K&M mandrel for neck tension
Check for brass length Trim, chamfer, and deburr if needed.
Tumble brass
Brush necks twice with brass brush
Clean primer pockets
tumble brass again
Ready for load.

I use die wax for both FL size, and Neck Size. Can this be simplified? Am I doing brass prep correctly? Am I missing steps? What do you guys think of using Dry lube when seating bullets? Any suggestions are welcome. Thank you.

you don't mention trimming. Trim all cases to same length after full length sizing and before neck turning.

 

[Deleted noremaximus]

Went to the range today, and for my surprise the the 140 RDF grouped well. I will be using .017 as my seating depth. .016-.020 seems to be my seating depth window. What do you guys think?

 

[Deleted noremaximus]

You guys called it. Going a bit towards jam solved the grouping issue. Thanks a lot guys.

 

[caihlen]

Good job. Nicely done.

 

[MattPeetz]

They may look nice but once you get out to distance you’ll see those fliers that are there in those groupings.

 

[Richard Coody]

I bet .010 off would be even better
Now fine tune your powder charge.

 

[Deleted noremaximus]

Match results at 600 yards. At .020 seat depth. I might be able to get a bit flater waterline at .017. What do you guys think. Total of 70 rounds.

 

[Deleted noremaximus]

All shots in x, 10, and 9 rings.

 

[Firearmsunlimited]

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.

Try a 5 shot group minimum and be sure the spread isn't shooter error.

In the first 3 shot targets it appears your groups could possibly be a result of “Bucking” - a slight push with the right shoulder on the butt in anticipation of recoil will move the sights, and the shot, in the 7-8:30 area.

In your latest targets it looks as if your trigger finger was placed too far into trigger guard. When rifle
fires, the finger moves back rapidly and drags against the right side of the stock, causing the rifle, and front
sight, to move to the left. Another cause is squeezing trigger on an angle, not straight back.

 

[INTJ]

Those who have success with the RDF report long jumps are required, which echoes my experience. I have become a believer in the Berger seating depth test which ranges from very short to very long jumps as an initial screening trial, followed by fine tuning around the best. Often the best jump is far longer than most folks would even consider, and therefore miss the boat.

This. Also, bullets seated deep are much less sensitive to going out of tune because of throat erosion. Once we get to .015 jump, then I think we need .005" increments to .040", then .010" after that. If we keep going, we'll need to go to .020" increments. I am not sure where, but somewhere past .100" jump I think seating depth changes no longer help us tune.