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

[lancetkenyon]

.0008 instrumental error, is 60% larger than your presumed level of accuracy of .0005. So, you are correct, that would indicate +/- 60% or 120% total margin of error.

Like I said, that's meaningless, but not as precise as stated or presumed, as there's no way to accurately measure to that level of precision with a simple handheld too.

So you are saying I could actually be getting .0002" variation in my seating depths?
Thanks for the vote of confidence.

See, I am more of a "glass half full" kind of guy.

 

[Phil Rizzo]

Before the full frontal charge launches, that is JJ Cale.
Mentioned in the song

 

[WA Coyote]

Good news is……..

Another couple 'thou and you'll be in the "Precision Hunter" range.

 

[Eric H]

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.

I've taken a lot from his videos.

 

[Jeffpatton00]

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.

I don't know this from personal experience but I've read that calipers sold as Mitutoyo are sometimes fake, even on Amazon. Has anyone run into this? Mitutoyo is pretty expensive so it's worth getting the genuine article.

 

[Elk Hunter 338]

I don't know this from personal experience but I've read that calipers sold as Mitutoyo are sometimes fake, even on Amazon. Has anyone run into this? Mitutoyo is pretty expensive so it's worth getting the genuine article.

would not surprise me in the slightest..

That is why you pay the money and get Mit, starrett, BS, interapid etc, direct or well known dealer!

 

[Mikecr]

For consistent CBTO, it helps to pre-qualify the ogive datums.
There is a tool referred to as a Bob Green Comparator (BGC), that does this in a comparative sense.
Once bullets with same ogive radius are grouped, they seat to a value and measure to this more consistently.

 

[MagnumManiac]

I have used an ogive comparator for many years in conjunction with those that attach to your caliper. I use Mitutoyo measuring tools for everything. As these are what we were told to use in the engine reconditioning trade.
I prefer to measure with micrometers that read to .0001", but .0005" for most bullet type measuring is fine.
I do not shoot un-sorted bullets if I want extreme precision, but for general hunting, I am not really that concerned with a few thou' difference here nor there in CBTO.

Cheers.

 

[Mikecr]

The tightest CBTO window I've had so far, as tested with group shooting, is 8thou.
I seat in the middle of window and keep my CBTO within +/- 4thou (very easily).
This with Starett indication & various gizzys

 

[FEENIX]

I don't know this from personal experience but I've read that calipers sold as Mitutoyo are sometimes fake, even on Amazon. Has anyone run into this? Mitutoyo is pretty expensive so it's worth getting the genuine article.

would not surprise me in the slightest..

That is why you pay the money and get Mit, starrett, BS, interapid etc, direct or well known dealer!

Yes!

 

[FlGunner]

I use Starrett dial calipers and also have a full set of mics that I can use with a block to measure base to ogive. I hardly ever use the mics…basically only after I find my final load to get an exact measurement. One can be plenty accurate if they're consistent. I line the dial caliper over the digital. Just personal preference. I use Starrett and Mitoyuo as millwright for different jobs. Both are good instruments to measure with.

 

[Brathany]

I should think it would be rather impossible to determine a .0002-.0005" seating depth variance effect on precision. Considering the throat erosion could also be varying that miniscule amount per round fired. Then also consider the average wind call error is greater per shot by orders of magnitude. I liken the notion to "So lost in the noise is a pin drop at a rock concert".

 

[Eric H]

Yes!

Just got one from through Amazon and returning it after talking with Mitutoyo online. It was not sealed in plastic and a battery was already installed. Red flags all around. They said each caliper leaving is sealed and they never install a battery.

 

[Beluebow]

Nobody here can shoot the difference between the numbers the squabbling is over.

Seems like a SAC infomercial to me. Don't get me wrong SAC makes some good stuff ( I own some of their stuff, including that press) but you can have consistent bullet seating a lot cheaper.