How To Get Consistent Seating Depth Every Time from an empirical source.

[FEENIX]

Now that I have your attention , "no," this is not necessarily empirical as to how or why reloaders test various seating depths. I also understand a lot of people do not care about Gavin. However, I think he did an excellent job addressing the elephant in the room. Take it for what it is worth. As with everything else, YMMV.

 

[lancetkenyon]

My take (without watching the video). For the perfect seat, you need perfectly consistent neck tension, perfectly annealed necks, and perfectly shaped bullets, a good consistent press...and a high quality digital caliper.

I can seat to within .0005" CBTO (I never measure COAL due to meplat differences, even with tipped bullets, Bergers, etc.) 98% of the time with once fired, freshly annealed, with just a bit of carbon left in the neck brass and either Berger or Sierra bullets. Some other bullets are far less consistent.

 

[Elk Hunter 338]

My take (without watching the video). For the perfect seat, you need perfectly consistent neck tension, perfectly annealed necks, and perfectly shaped bullets, a good consistent press...and a high quality digital caliper.

I can seat to within .0005" CBTO (I never measure COAL due to meplat differences, even with tipped bullets, Bergers, etc.) 98% of the time with once fired, freshly annealed, with just a bit of carbon left in the neck brass and either Berger or Sierra bullets. Some other bullets are far less consistent.

SAMEZIES!!!

And i will take it a step further and add... a constant steady downward stroke of the press handle to a soft stop every time all the time

CONCISTANCY is key!

 

[WA Coyote]

What kind of calipers do y'all use to measure these rounds that are accurate to .0005"?

Just for reference, .0005" is 1/8th the thickness of a sheet of paper.

 

[Elk Hunter 338]

There really is only one brand to buy for ultimate accuracy ...... MITUTOYO!!!

I wont buy it unless it measures to that or less!

But, you know, I'm kinda into that sorta stuff

 

[WA Coyote]

There really is only one brand to buy for ultimate accuracy ...... MITUTOYO!!!

Interesting…. From Mitutoyo's website:

"Caliper Accuracy
The measurement accuracy of the caliper, sometimes termed instrumental error, may be expressed in steps. The first step for the 0-200 mm (0-8 inch) range shows a measurement uncertainty of ±0,02 mm (±.000 8 inch) over this range (when set to zero with the jaws closed) which increases by around ±0,01 mm (±.000 4 inch) for each additional 200 mm in range thereafter. This trend continues all the way up to 1000 mm."


Meaning, the instrumental error is 60% greater than your expressed "concistancy" of .0005".

Even with the induced margin of error, you're loading to a very consistent length, it's just not as consistent as you presume.