I learned how to better adjust my seating depth

[BJung]

I don't have a seating die with micrometer settings and had problems over seating bullets in the past. I would initially seat my bullet slightly, take a measurement, screw the seating stem down, seat, measure, and sometimes find a correct OAL. This last time, I seated my bullet slightly and continued doing the same process until I was coming close to the desired OAL. After my last measurement, I seated the cartridge into the shell holder and rose my case into the die. The pressure prevented the stem from moving. Then, lowering my case to remove the tension, I turned the stem down 1/4-1/2 turn at a time and then measured the OAL. If the bullet needed further seating, I repeated this new method of which I had much more control over the seating process. With the OAL determined, I unscrewed the seating stem, turned the die body until it touched the case and added a 1/8 turn for a slight crimp. Then, with the cartridge up, I lowered the stem to the the properly seated bullet and locked everything down. If anyone has a different method, please share.

 

[AJC1]

I mark my die bodies with a black sharpie and the press to clock them. I measure oal or base to ojive to see how much more I need. I measure the base of the die to the top of the stem and make the exact adjustment I need. I don't crimp while seating it induces variation and other problems.

 

[CQB45ACP]

What you describe seems very complex to me so I’m guessing it’s rifle—regardless I doubt I’d have the patience to do all that. Honestly I don’t even know what it’s all for.

For what it’s worth—

For 230gr RN (pistol obviously) I have two dies. One a Lee the other a Redding competition w/micrometer. The Redding does not have a crimp function. The Lee could crimp but I don’t use it.

The standard stem on each uses the ogive.

I just set them up one time as described by mfr (bottom of die touching shell holder) and let the seating adjustment do it’s job on the bullet. I don’t recall moving/adjusting the die bodies since I first screwed them into the press.

On the Lee I mark it with a sharpie at my most common OAL—1.260” and then adjust up or down as needed.

The Redding just sits there at “0” or thereabouts on the scale waiting for any necessary adjustment. I also have some sharpie marks on the die body to reveal any movement. Really the die is the same as the Lee but cooler looking.

I only use two bullets these days—Extreme or Berry’s. As long as I’m using the same bullet I seldom have any adjustment once I get the initial measurement with my micrometer to make sure it’s 1.260”.

I get essentially the same accuracy from either die. For my usage, the Redding micrometer is an unnecessary gimmick. But again it’s cool looking.

 

[WeekendReloader]

I screwed the seating die body into position and locked it. I then use the adjustment on the top to make changes.

I have different seating stems for different bullet nose shapes/profiles, so this is how I do it.

1. Install the correct seating stem.
2. Place my sample cartridge in the shell holder.
3. Raise the ram.
4. Screw down the seating stem adjustment knob until I feel pressure.

This gets me really, really close to my desired COAL. I may or may not need to adjust a bit on the first bullet I seat. I'll double check COAL on the next few, then it's off to the races.

It helps a lot to keep samples of what you are loading. I just seat a bullet into unprimed brass and keep it in a ziplock baggie with that caliber's dies.

 

[GeoDudeFlorida]

I don't have a seating die with micrometer settings and had problems over seating bullets in the past. I would initially seat my bullet slightly, take a measurement, screw the seating stem down, seat, measure, and sometimes find a correct OAL. This last time, I seated my bullet slightly and continued doing the same process until I was coming close to the desired OAL. After my last measurement, I seated the cartridge into the shell holder and rose my case into the die. The pressure prevented the stem from moving. Then, lowering my case to remove the tension, I turned the stem down 1/4-1/2 turn at a time and then measured the OAL. If the bullet needed further seating, I repeated this new method of which I had much more control over the seating process. With the OAL determined, I unscrewed the seating stem, turned the die body until it touched the case and added a 1/8 turn for a slight crimp. Then, with the cartridge up, I lowered the stem to the the properly seated bullet and locked everything down. If anyone has a different method, please share.

What kind of press? What kind of dies? How often do you change projectiles and case lengths?

I only use single-stage presses - a Lee Hand Press and an RCBS Partner - so I'm removing/replacing dies every time I change calibers. Also, I use the same dies for .32S&W/H&R/S&W Long/Mag, .38Spl/.357Mag, .44Russ./Spl/Mag, etc. so I have to adjust my dies to match the different cartridge lengths. I also load several different bullets and styles for each caliber. I follow a similar process to what you describe but I have "standard" APD's like @WeekendReloader does for some of my loads that I can go off of to get close and shorten the process. For dies where I don't have a standard, I follow the die's directions, use a sized-n-flared empty case to set the crimp - if any - and run one case all the way from flare-to-final OAL, then use an inertial puller to take it apart and put the case through processing again with primer/powder.

IF I was using a turret or only loading one cartridge over and over again, with no variance of projectile or case, I might be tempted to lock everything down and never adjust more than the seating stem - but that's not how I roll (ammo).

 

[Varminterror]

Pretty standard practice. Find the seating length with the die high, raise the stem, lower the die to find your crimp, then reference the stem on the dummy bullet. I was taught that method over 30yrs ago.

Resetting the die works the same - use the dummy to set the seating die.

Also worth noting - if this is rifle ammo, don’t bother crimping.

 

[243winxb]

RCBS instructions-
These instructions
are for seating the bullet without crimping.
1. Place a sized, primed and powder-charged case into the Shell Holder
and run it to the top of the press stroke.
2. Screw the Seater Die into the press until you feel it touch the mouth of
the case.
3. Back the die up one full turn and set the die Lock Ring.
4. Unscrew the Seat Plug several turns.
5. Lower the case and insert a bullet onto the case mouth. Slowly run the
case into the Seater Die. Check the bullet for proper seating depth. If
the bullet is not seated properly, adjust the bullet Seater Plug in small
increments until the proper depth is obtained. Once the proper seating
depth is attained, tighten the Seater Plug Lock Nut.

 

[BJung]

[QUOTE "]What kind of press? What kind of dies? How often do you change projectiles and case lengths?. [/QUOTE]

I use a Rockchucker and RCBS dies. I change my dies out a lot because I assemble a lot of test loads. As soon as I find my accuracy load with the correct COAL, I'll assemble a dummy load

 

[BJung]

Pretty standard practice. Find the seating length with the die high, raise the stem, lower the die to find your crimp, then reference the stem on the dummy bullet. I was taught that method over 30yrs ago. Resetting the die works the same - use the dummy to set the seating die. Also worth noting - if this is rifle ammo, don’t bother crimping.

.

Controlling my seating depth by adjust the seating rod was a problem. Turning down the body without backing out the seating stem pushed the bullet in further.

I don't crimp my bolt action reloads. What about semi-autos? I was making a slight crimp so the bullet would stay in place.

 

[243winxb]

What about semi-autos?

Measure COL before & after chambering a round. If bullets moves to much, increase neck tension. Make the expander diameter .001" smaller.

Measure case neck OD before & after seating a bullet. After seating, has OD increased by a minimum .003" ? This should provide more the 35 pounds bullet pull, a military 5.56 standard.

 

[Varminterror]

What about semi-autos? I was making a slight crimp so the bullet would stay in place.

A proper feeding auto doesn’t need neck tension as a bandaid solution to hold bullets in place when poor feeding slams them into ramps, tenons, or extension lugs. If an auto loading rifle is setting back bullets from poor feeding, fix the rifle. We’re stripping rounds and feeding them into chambers - why would we tolerate poor feeding in autoloaders running bullets into stuff when we don’t tolerate it in our bolt guns?

 

[BJung]

Measure COL before & after chambering a round. If bullets moves to much, increase neck tension. Make the expander diameter .001" smaller.

Measure case neck OD before & after seating a bullet. After seating, has OD increased by a minimum .003" ? This should provide more the 35 pounds bullet pull, a military 5.56 standard.

So, what you are saying is make a few dummy rounds seated with a with varying crimps. The lightest crimp in which the bullet doesn't move is what I am looking for. Or, use expander mandrels to expand the neck so the neck tension will vary and find the corrected tension such that the case neck expands .003" and the bullet doesn't move.

 

[243winxb]

No crimp. use expander mandrels to expand the neck so the neck tension will vary. Movement of no more the. 003" is ok.

https://www.sierrabullets.com/reload-basics/reloading-for-semi-autos-and-service-rifles/

 

[BJung]

I've tried expanding my case neck using a mandrel. After seating a bullet, the concentricity was poor. How do you avoid this?

 

[Varminterror]

So, what you are saying is make a few dummy rounds seated with a with varying crimps.

Varying neck tension, not varying crimp. Crimp isn’t neck tension.

 

[243winxb]

After seating a bullet, the concentricity was poor. How do you avoid this?

Don't over work the neck by sizing more then needed, may help? Bushing die or honed neck with a full length die.

I never check concentricity.

 

[AJC1]

I've tried expanding my case neck using a mandrel. After seating a bullet, the concentricity was poor. How do you avoid this?

Your assumption is that the mandrel process is the offender and I propose it's your seating die. Are they are concentric out of the sizing die?

 

[kalielkslayer]

I have the RCBS die instructions on my bench. I follow instructions.

 

[AJC1]

I have the RCBS die instructions on my bench. I follow instructions.

Are you cheating on the exam.

 

[BJung]

Eh, this is getting off topic but to answer your question, I tried neck sizing with a FL sizing die and then use a mandrel to control neck tension. But, after seating the bullet, the round wasn't concentric. I went back to using a Lee collet neck sizing die. I owned one and had no concentricity problems; but I damaged the die, so I then had a new custom die for my Arisaka made. I plan to use this new die for my next set of testloads. Currently, I'm testing an accuracy load with various seating depths.

 

[Varminterror]

Eccentricity issues with a mandrel expander is almost always non-uniform case neck thickness.

 

[jmorris]

I have many more regular dies than micrometer ones, I use this method a lot.



Most of the rifle stuff I load doesn’t get crimped but you can independently move a seating stem and die body, measurable amounts, in either direction.

 

[AJC1]

I have many more regular dies than micrometer ones, I use this method a lot.

That's a fixed version of the method I described. I just adopted the same method from adjusting my Wilson chamber seater. Obviously I just measure the top and stem in that situation

 

[Tilos]

Just stumbled onto this thread so I am adding my method of accurately adjusting any bullet seating die using a dial caliper that most reloaders already have.


Write the reference measurement in your loading book/log so you can repeat it.
Same deal with a powder measure, and record that reference measurement in your load book too.
I have ground off the end of the screw flat for easier measuring.

works for me,
jmo,
.

 

[Tilos]

Just stumbled onto this thread so I am adding my method of accurately adjusting any bullet seating die using a dial caliper that most reloaders already have.
View attachment 1117796
View attachment 1117799
Write the reference measurement in your loading book/log so you can repeat it.
Same deal with a powder measure, and record that reference measurement in your load book too.
I have ground off the end of the screw flat for easier measuring.
View attachment 1117798
works for me,
jmo,
.

OK More info as to how this method works and only requires one bullet to be seated to dial-in the OAL.

1.- Back off the seating stem and seat a bullet purposely longer than OAL target.
2.- Measure that round for Over All Length (OAL) and note the amount it is too long (actual OAL minus desired OAL. (A).
3.- Measure the seater stem protruding above the die (B), as pictured.
4.- Subtract A from B to get the new stem protruding dimension (C) for the correct OAL
5.- Adjust the stem height to the calculated stem height (C) in step 4.
6.- Reseat the long bullet again to verify the new setting gives you the OAL you want.

Another way to estimate the amount of adjustment is to mark a line on the seater stem, measure it, turn it in 1/2 turn and measure it again.
If it is shorter by 0.025" for 1/2 turn then a full turn will be 0.050", 1/8 turn would be 0.0125" shorter and so on.
That really relates to the seater stem thread pitch (TPI) but most reloaders don't have a thread pitch gauge, so this measure/adjust/re-measure is the easiest way to determine the value of a partial turn of the stem.
So, a micrometer adjuster is nothing more than a 40 TPI threaded stem with 25 graduations marked around the outside.
A marked stem:


Stem Measuring:

One more thing, if the seater stem has a locknut, I remove it and put a length of masking tape over it so it doesn't turn if I bump into it.

So, there you go, way too much info (bloviation) about setting a seating die.
jmo,
.