Bullet seating depth

[Megalodon]

My question is about what consistency I should be getting.

My first go reloading was 25-06 with Nosler Partitions using RCBS dies. I chalked up my inconsistencies to the tip of the bullets possibly being deformed.

Second go was 22-250 with 52 gn ELD-M using Lee dies. These tips won’t deform but I’m still getting around .002 variance, sometimes jumps to .005. Is that something that’s expected and I should ignore? I’ve been backing out the seater a 1/4 turn and easing back up to the depth I want, huge pain in the ass.

 

[BRTreedogs]

Are you getting this in the same lot?
Are you measuring OAL to the bullet tip or CBTO with a comparator?
If oal tips vary and you need to switch to measuring with a comparator off the ogive.
Or you have removed your die from the press then when you put it back in your new lot is different?
If this it hard to put the exact torque on the die every time.
Run a micrometer die, or a turret press so you can leave the die installed.

 

[Buck Naked]

OAL is the last detail to fuss with.
Seat so they fit the mag and feed reliably , seating depth is for BR shooter dreams

 

[Megalodon]

Are you getting this in the same lot?
Are you measuring OAL to the bullet tip or CBTO with a comparator?
If oal tips vary and you need to switch to measuring with a comparator off the ogive.
Or you have removed your die from the press then when you put it back in your new lot is different?
If this it hard to put the exact torque on the die every time.
Run a micrometer die, or a turret press so you can leave the die installed.

Just measuring OAL. How would it work with a comparator if I’m trying to hit a certain COAL? Like what CBTO measurement would I be looking for if I wanted a 2.350” COAL? Or is that the wrong way to think about it?

Need to google CBTO more obviously.

This was all from one box of bullets and one sitting, no changing of die.

 

[Megalodon]

OAL is the last detail to fuss with.
Seat so they fit the mag and feed reliably , seating depth is for BR shooter dreams

This is helpful. I’d love to be able to set the die and run through seating 100 rounds and only check COAL every so often.

Just getting into working up loads and it was bothering me to hear people talk about determining seating depth by changing distance from the lands by .010 when I can get +/- .005 unless I’m easing each round up to the desired length.

 

[BRTreedogs]

Cartridge Base To Ogive.
So the ogive is really the only repeatable measurement, it's also what the cup in your die is pushing on.
You jump to the lands is also based on ogive.
Easiest way would be to produce an Oal dummy round based on a length you know shoots well.
Then measure it with the comparator.

But bullet tips are know to vary.

Look up panhandle precision on YouTube.

 

[ID_Matt]

bullet tips definitely vary so CBTO is going to be the best measurement. Get a Hornady comparator kit and measure the distance to the lands of your rifle. If your die is working properly it is grabbing on the ogive, not the tip. You are probably loading more consistent than you think in terms of CBTO.

 

[Wrench]

Agree on not using the tip for anything beyond confirming itll fit where you need it to.

One overlooked piece to this is neck tension. Not many aneal brass nor measure neck thickness, often myself included....however, if you're chasing sub .002" consistency, you are going to need to stay on top of brass flow and hardening.

Quite honestly, .002" is likely not something that 99.99% of shooters can out shoot and very few bullet/powder combos will even show a measurable difference that can rule out pilot error.

 

[bradb]

I tend do rough seat test first. Mostly talking new gun/barrel, I typically take a random charge with enough to sight in and do that at 100 and will also have a seat test loaded to shoot at 200. That is the max distance at the local range. The rest of my load work is typically done at 500 ish and will re visit seat length for small adjustments at distance also

 

[Low_Sky]

This is helpful. I’d love to be able to set the die and run through seating 100 rounds and only check COAL every so often.

Just getting into working up loads and it was bothering me to hear people talk about determining seating depth by changing distance from the lands by .010 when I can get +/- .005 unless I’m easing each round up to the desired length.

Use your caliper and measure 10 bullets straight out of the box. You should see that they are not all the same length. This variation in bullet length is why measuring Cartridge OverAll Length (COAL) is meaningless as long as your longest finished cartridge (accounting for this variation in bullet tip length) fits in your magazine and feeds reliably.

As suggested, you need to get a comparator and measure Cartridge Base to Ogive Length (CBOL). You should be able to set your seating die and process a batch of ammo with the exact same CBOL, and varing COAL (because of the bullet length variation).

 

[jakelogsdon]

https://www.hornady.com/reloading/precision-measuring/precision-tools-and-gauges/lock-n-load-bullet-comparator#!/

 

[MuleyFever]

I get the same thing using my RCBS micrometer seating die. For each round I back the die off about .01 and then work it to my desired depth measuring to the OGIVE. If I just leave the die alone I will get a small variance.

 

[Unknown Munitions]

With our Redding Competition seaters there are several things that can affect setting depth variance measured at the Ogive. You need a clean die and a clean correct stem to start with, then proper cam over and a tight die with no movement. If load is near capacity then we use a sonic toothbrush to settle the load and avoid pushback from the powder. We also have seating stems that are honed to match certain bullets that are known for receiving the ugly donut no matter what you do. You should never have to adjust the die throughout a run of ammunition.

 

[Muley Buck]

You should never have to adjust the die throughout a run of ammunition.

Yes, I do agree. Seating depth should be consistent, but that is on the understanding that brass prep is carefully paid attention to and consistent as well. If the necks aren't consistent (in more ways than one) seating depth won't be either.

 

[WeiserBucks]

OAL is the last detail to fuss with.
Seat so they fit the mag and feed reliably , seating depth is for BR shooter dreams

You sir , are gravely mistaken.

 

[cornfed]

Yes, I do agree. Seating depth should be consistent, but that is on the understanding that brass prep is carefully paid attention to and consistent as well. If the necks aren't consistent (in more ways than one) seating depth won't be either.

Can you please explain to me how brass prep affects seating depth?

 

[WeiserBucks]

Inconsistent neck tension and length can lead to issues . Brass prep is easy to control and should be considered essential to any handloader.

 

[cornfed]

You sir , are gravely mistaken.

I agree with WB here.
First thing you should be doing is buying both a Hornady bullet comparator set, and a their headspace kit. No one... NO ONE should be reloading without a good way to measure what you're doing. These will allow you to find the real base to ojive measurement from the lands. You can then back it off 0.015 to 0.0020 (if your mag box allows) and start testing charge weights.

If your mag box doesn't allow you to reach the lands... set the bullet 0.015 short of the mag box, and make sure it'll feed do your OCW tests, and once you find a sweet spot with charge weight try to seat the bullet deeper 0.003 at a time to see if it tightens up or atleast nets a "rounder" looking group.

With the headspace kit you'll be able to measure your fired rds, and then bump the shoulder back 0.002-0.003 in a hunting rifle.

 

[cornfed]

I'll also say if you're using nosler and hornady bullets they're going to vary more than a some other mass produced bullets. That means if you're serious about accuracy, and you're going to use those bullets.... your best bet would be sorting them BTO . Good luck.

 

[Muley Buck]

Can you please explain to me how brass prep affects seating depth?

All these things can lead to inconsistent seating depth regarding brass prep:
Neck thickness
Neck length
How dirty the brass is (including carbon in the neck)
How hard or soft the necks are (annealing)
Lubed or un-lubed necks
How consistent the operator is with each stroke of the press.

Im sure there is more and that is just off the top if my head. Like most things in precision handloading, attention should be paid on setup and prep as it will lead to a much better finished product with less frustrations in the end. In short, start right, end right.