Seating depth - does it even matter?

[huntnful]

Thanks. I think it's about the limit of my ability to shoot consistently with an 8lb rifle prone off a bipod & rear bag.

I routinely achieve this level of precision following the approach of:
1. Seat 0.050 off
2. Powder charge estimated to get the velocity level I want
3. Done

with a well-built rifle & good barrel. And good components.

Same here. But I normally do .010-.020 off

 

[zrodwyo]

Last week, I shot a 20-round group with my go-to 6.5 SAUM load as a control. I’ve done this many times, so I have a solid understanding of how the rifle groups. Next, I shot a 30-round group with seating depths ranging 0.100 inches from the longest to the shortest. Some of the rounds had been sitting on the shelf for two years, while others were loaded that day. The group with varying seating depths fell within the normal distribution, and the muzzle velocity standard deviation (SD) was also within the normal range.

My takeaway from this test is that I’m not willing to burn through components to determine if seating depth significantly impacts group size. The amount of rounds that it would take to do load development would burn out a barrel.

I’m sticking with my belief that a barrel either shoots well or it doesn’t. If a barrel can’t produce good groups with a near-max load using the bullets and powder I stock piled, it’s going in the trash.

 

[Harvey_NW]

Last week, I shot a 20-round group with my go-to 6.5 SAUM load as a control. I’ve done this many times, so I have a solid understanding of how the rifle groups. Next, I shot a 30-round group with seating depths ranging 0.100 inches from the longest to the shortest. Some of the rounds had been sitting on the shelf for two years, while others were loaded that day. The group with varying seating depths fell within the normal distribution, and the muzzle velocity standard deviation (SD) was also within the normal range.

My takeaway from this test is that I’m not willing to burn through components to determine if seating depth significantly impacts group size. The amount of rounds that it would take to do load development would burn out a barrel.

I’m sticking with my belief that a barrel either shoots well or it doesn’t. If a barrel can’t produce good groups with a near-max load using the bullets and powder I stock piled, it’s going in the trash.

Agreed. I've done a similar test with neck tension from stuff that was loaded for a long time and I ended up having issues and pulled bullets to diagnose (tight on close from primers not fully seated), when loading back up bullets seated with very little resistance and I even added a new lot of bullets into the mix. All fell within the expected cone.

 

[TheWhitetailNut]

You guys dont know what you are talking about. You are regurgitating fuddlore.

Have any of you performed modal analysis? What is your experience with structural dynamics? How are you testing the effects of harmonics on your accuracy? Do you have an FEM model that proves your claims? Can you provide your test results for analysis?

You are convoluting a simple process. you dont know what you are talking bout. Any challenges to the dogma are often met with aggression by "zealots" like you. Present some data and evidence and I will happily change my mind.

No. none of that. Probably the best shooter of our time said it. I tried it. It worked.

NO PFM required.

 

[Packmansion]

Thanks. I think it's about the limit of my ability to shoot consistently with an 8lb rifle prone off a bipod & rear bag.

I routinely achieve this level of precision following the approach of:
1. Seat 0.050 off
2. Powder charge estimated to get the velocity level I want
3. Done

with a well-built rifle & good barrel. And good components.

I follow the exact same formula. Works like a charm. I have yet to have a rifle that doesnt group well with this approach. Instead of fiddling with depth and charge I collect data on my SD and use that to determine my wez.

 

[greyghostnw]

Seating depth. Does it matter. That is the title. After skimming through the responses and thinking’s about why one would respond positive or negative to it i determined at least for i my response should be considerate of the intention or phase of load development.

For the initial point of development I determine if im going to single feed or feed from mag for initial starting depth. If mag length dosnt matter i choose .020 off touch as a gaurd rail with the bullets i use it is a great starter in my past barrels and component combos…but could be less or more. Any closer i know i dont want for hunting to allow for foreign matter and function though. I could start anywhere it dosnt matter to some extent .. I can make a load from really any starting depth from powder charge, seating depth, diameter interference fit with bushings and mandrels tuning primer depth and or crush and so on…Not everyone has the same goal of there loads but i definitely use seating depth to fine tune after level velocities and always have a load that shoots to my expectations and i barely change during life of barrel. Either way the title of this thread is pretty vague and one could perceive its meaning in different ways.

So my view looking at this title i will say seating depth dosnt need to have a specific starting place it can be in various depths to start. Where i believe it matters and utilize it to benifit my load and accuracy is fine tuning after i level velocities. There still is a little tweaking for my expectations but certainly testing a group that shoots small can become smaller or bigger from seating depth. Everyone’s expectations are different and will have different willingness or effort to get there. Either way good luck and remember this is supposed to be fun and relaxing…… not to mention rewarding when it all works out.

 

[Harvey_NW]

Where i believe it matters and utilize it to benifit my load and accuracy is fine tuning after i level velocities. There still is a little tweaking for my expectations but certainly testing a group that shoots small can become smaller or bigger from seating depth.

Again, that is essentially the crux of this thread, you're not actually "fine tuning" anything, and the groups don't get bigger and smaller by adjusting seating depth. What you're observing is random distribution and small sample variability. Any time this theory is tested to statistical validity where a true cone of fire is established, the groups stabilize and are essentially the same size. I.E. - seating depth doesn't matter (for precision).