Micrometer Seating Stems - A Primer

Sorry, I'm not offering info. Don't know anything much about them. But I'm interested..did a Forum search, the topic comes up but bits here and there. Google gets more but again, info spread around..

What might be interesting to have here is the following sort of info-

Do you use them and for what applications, like, just benchrest comps or for hunting also?

Can you buy a micrometer seating plug from one manufacturer, say Redding, and use it in another's die, say Lee?

Apart from the obvious of super accurate, repeatable seating depth achieved, are there other particular benefits?

Which ones do you best like?

Is a micrometer stem caliber specific or just bullet design specific - STD/VLD, or both?

Is Forster better than Redding, why?

Better for just some calibers or many?

What are the tips, tricks, gotchas?

Is it worth getting into and for what sort of shooter?

Etc

Only used the Hornady one so it’s not high end I’m not producing Fclass loads but I’ve leaned:

I believe the Hornady micrometer will be specific to their brand of dies.

Micrometers are useless unless you are getting consistent seating depths to start with. For me that was getting the correct seating stem for each projectile. Annealing brass likely helps as well.

Once you can produce consistent seating depths then the micrometer is great especially when making different loads with the same die. I mark the die and once done loading one projectile I can wind back to another setting. At worst its usually within a few thou of where I need it

The markings on mine are not calibrated. They mean nothing as a means of measuring actual seating depth. For instance winding in 2 hash marks does not correspond to 2thou etc. I imagine this is the case for even custom die sets? It doesn’t matter tho because the important thing is that it give you a reference point that you can work off.

I don’t use it for my main hunting rifle and still achieve very low SD with basic Lee dies. I will be getting premium dies next time I get a new cartridge to experiment with as that’s becoming more of a hobby than actually shooting animals.

Interested to learn more from our bench rest gurus.

Annealing brass likely helps as well.

What he said.

Had the redding, now the foster, the foster has a bigger top bezel & so easier to read increments. I tend to measure length to ogive anyway so the plain bench rest seater is all I would buy. Got a old Bonanza BRS that only adjusts with the spindle & all cases must be FLS, produces top rounds, length wise & concentricity.
Attachment 240948

I have a few of the Redding Micrometer seating stems and really like them. Made sense to get these as I already had Redding dies too. You can get them in VLD or standard ogive also.

Quite handy for when you are loading different projectiles in the same rifle, of for multiple rifles of same calibre. I just have a different stem for each bullet so I can chop and change stems set for each one.

Makes for a relatively cheap multiplier for one set of dies. E.g. I have 3 stems for my 7mm Rem Mag alone.



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@SPEARONZ, what are the issues/fixes in getting consistent seating depths in the first place? Something I've struggled with. No point in measuring Cartridge OAL especially with soft points- have to measure from ogive. I have a number of calibres and dies from Lee, Lyman, Hornady, RCBS, Redding..frankly, whatever was available when I got into that calibre. Have not noticed Lee being any worse than the "premium" dies but not wanting to start a argument about which dies are best - just keen to hear what others found for themselves. Some.of my most accurate ammo has been 7x57mm Mauser produced with a rather old set of Lyman Rifleman dies and shot out of an Interarms Mk X using Remington 150gn Corlokt projectiles.

Agree I like the Lee dies, my FLS & Collect neck dies / Univeral decapper are Lee. Redding body dies are usefull as you can bump the shoulder with touching the neck.

I’m no expert man and a lot of it is probably a bit of superstition or voodoo.

1-Anneal brass
2-Use the correct seating stem or modify one to fit your projectile
3-Use graphite powder
4-Ensure you can use callipers in a way that give consistent readings
5-Insert as many other steps into you brass prep regime as you feel necessary

More experienced people can talk to neck tension etc but it’s something I’ve been lucky enough not to need to reach my accuracy goals.

I was looking at this subject myself a few days ago and one guy on YT made a really simple observation. If a seating die has 28 threads per inch, and you do some basic maths it means that one full turn of the die means that the seating depth changes by 35.7 thousandths of an inch. Half a turn then is 17.8 thou. a quarter turn is half that, and so on. Someone with a 3D printer could print a dial to fit over the top of the unit with segments marked off.
Here is a link that is worth a look, he is a little long winded but interesting none the less.

https://www.youtube.com/watch?v=DTPECIm4CGM&t=1397s

Quote:

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Originally Posted by SPEARONZ

I’m no expert man and a lot of it is probably a bit of superstition or voodoo.

1-Anneal brass
2-Use the correct seating stem or modify one to fit your projectile
3-Use graphite powder
4-Ensure you can use callipers in a way that give consistent readings
5-Insert as many other steps into you brass prep regime as you feel necessary

More experienced people can talk to neck tension etc but it’s something I’ve been lucky enough not to need to reach my accuracy goals.

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I recently stopped using my $90 Frankford Arsenal Digital Calipers in favour of some $120 Hornady Dial Calipers. Same rationale as favoring good balance beam scales over $100 digital scales. What a difference it makes. The reading is the reading no longer an approximation.

Forster are making rings like this with notches for each thou. Little on the expensive side for 1 ring, but work well

https://www.brtshooterssupply.com.au...olt-lock-ring/

Iv got Hornady and Redding the Redding are better but only because their easy to read in saying that I’m not that impressed with my saum Redding seating die compared to my 7blaser mag Redding seating die I remember the blaser mag was true to the dial the saums is not

My application is hunting I prefer Forster

I've found the hornady stem to be OK but if you want ultra exact results then you need to faff with everything you can think of. Annealing, brushing out the red oxide and then dusting your projectiles.

I can't stand the crude bolt adjustment you get with an RCBS std seater or worse (the heavy bolt on the lee seater).

I check the first 3 or 4 round with the comparator / calipers to make sure I'm at least .02" off and then I just do 50 in a row after that. Or .1" off the lands if it's my own pc cast projectiles.

Whidden has even better markings to read than the Forster.