Seating Depth

[savageshooter86]

I am needing some help understanding the relationship between neck tension and bullet seating. If you have brass with slightly different neck tension(less than 0.003) how much will that change seating depth using same die and bullets and brass?

For example if you set up die to seat to 2.205" ogive and use same method, but you use brass with varying neck tensions, how much will that change the seating depth

 

[Longshooter70]

It shouldn't change seating depth any.... Your die and the way you have it set up on your press will determine seating depth. You may have to use a little more force on tighter necks. By the way, shooting with different neck tensions is a great way for bad accuracy. Hopefully, all your neck tensions should be as close to possible to the same as you can get them....

 

[tclaunch]

Easily .002" to .003".

 

[fdshuster]

"Hopefully, all your neck tensions should be as close to possible to the same you can get them".

And a good way to better assure neck tensions that are the same (or very close), is to keep your brass segregated as it relates to number of times loaded. Do not mix brass loaded a couple of times with brass that has been loaded 15, 20, etc. times.

Yes, you will still have some differences, since brass will "age" differently, but it should not be enough to matter.

 

[savageshooter86]

Thanks. Reason asking is I had die set up and was getting different reading for ogive by several thousandths and was trying to figure out what might have been causing this. All brass was fired same # of times(2) and had same neck wall thickness and same runout.

 

[woolenmammoth]

I recently did some tests with a 20 Tac and 4198, 3 thou difference in neck tension translated to different vertical. loaded 20 rounds, mixed it all together, shot the same POA and had two neat groups on top of each other. Ive only tested it for that cartridge and powder, but if it was me, I'd sort that brass. As mentioned, its also real wise to keep your brass sorted by the amount of times its been sized. My new brass goes into a plastic box of some sort and will always go back into that same box, which has tape on it which gets a mark each time it is sized and if it was nk or fl sized. Seems like a clerical nit picky thing, but its so completely not.

 

[260Ravage]

One thing i may add: In my experience, Whenever different neck tensions show up by way of feeling it when seating the bullet;if I reseat the bullet by sending up through the seating die once again, the bullet seating depth of the rounds come out about exactly the same. I beleive there is just enuf 'give' in the equipment that if neck tension is a little on the stout side on a round the bullet stops seating prematurely. just say'n,,,,,I may be 'all wet' on my theory, but,,
That's my story and I'm stick'n to it.
Terry

 

[savageshooter86]

Ok I do keep detailed nots about the brass and what was done and etc..... I know different neck tension will cause different accuracy

I just pulled 17 loaded rounds and re-adjusted my Forster Ultra seater to get me to the 2.204 ogive I want. Worked good for 4 or so rounds then I started getting different readings. 2.035(which this is fine with me) for about 5 rounds then started getting 2.211 for about 3 rounds. So adjusted die and got 2.203" and then tried a few more. Then got 2.209 and 2.197 and 2.198"

This is driving me crazy. Die is adjusted and lock ring and seater lock nut is all secure and tight. Nothing changes

Not sure what is going on

 

[Catfish]

The difference in the ojive will have little to no difference on neck tention. And the difference in the seating depth is not as critical as you might think as the jump to the riflings stays real close to the same. Unless your your shooting compation where a couple of .000 might make a difference don`t worry about it.

 

[Killshot]

I just pulled 17 loaded rounds and re-adjusted my Forster Ultra seater to get me to the 2.204 ogive I want. Worked good for 4 or so rounds then I started getting different readings. 2.035(which this is fine with me) for about 5 rounds then started getting 2.211 for about 3 rounds. So adjusted die and got 2.203" and then tried a few more. Then got 2.209 and 2.197 and 2.198"

What bullets are you using?

Are you measuring using a comparator and caliper?

 

[K22]

"Hopefully, all your neck tensions should be as close to possible to the same you can get them".

And a good way to better assure neck tensions that are the same (or very close), is to keep your brass segregated as it relates to number of times loaded. Do not mix brass loaded a couple of times with brass that has been loaded 15, 20, etc. times.

Yes, you will still have some differences, since brass will "age" differently, but it should not be enough to matter.

Totally agree - this has been my experience - each rifle has it own set of dedicated cases which are rotated in the shooting / reloading cycle. For example - I dedicate 60 cases to a given rifle (100 for ones I shoot alot) divided into 20 cases groups label 1 - 2 - 3 (for 60 cases) housed in MTM 20 capacity cartrigde boxes.

 

[savageshooter86]

178 BTHP bullets. All have been fired same and processed same way.

 

[jcampbellsmith]

...For example if you set up die to seat to 2.205" ogive and use same method, but you use brass with varying neck tensions, how much will that change the seating depth

For each load, I have a target ogive measurement written down on my sticky for the load I am about to load. I roughly preset the seater, but I don't record the previous reading from the micrometer. I seat the first bullet and measure the ogive. I then adjust the seater to give me the actual ogive measurement I want. Sometimes I seat the bullet too far in and use a kinetic hammer to pull it partially out. At some point I am happy that the first round meets my spec. I generally mark this first off round as a fouler. Occasionally the second round doesn't meet my expectations and again I will mark it as a fouler.

Once I get into my stride, I load the remaining rounds. With good brass and quality bullets, I get +- 1 thou of seating variation. Some bullets are more uniform than others. If I was getting more than +- 2 thou variation on seating, I would be looking at my brass prep. I get the odd Remington case where the bullet just slides in and seats too deep. I mark the case as a fouler and cull it after firing.

If your seating is varying dramatically, look at your brass prep.

Regards JCS

 

[lpreddick]

awhile back i was having the same problem...seating depth measurements using a bullet seating comperator would vary .005 with necks of lesser tension seating deeper than ones with tighter tension. checked everything, then read on this site by somebody (can't recall, but thanks again) that loose necks allow the bullet to seat with the least amount of resistance IN the seating stem. a tight neck resist seating and the bullet goes INTO the hollow portion of the stem and you will see a ring just proximal to the bullet's tip, sometimes it can be quite prominent if neck tension is excessive. these will invariably measure longer and since these neck tensions are tighter, they will shoot differently than ones with a looser neck tension. understand this has helped me understand how important neck tension is when looking for extreme accuracy. variations in neck tension seems to come from several sources...aged brass and varying thickness possibly the two most common. i have tried using a wilson expander in hopes of getting all internal necks the same, but am not sure this works as well as annealing and turning, then getting the "feel" as the bullet seats and when they all feel the same they invariably shoot the same.

 

[savageshooter86]

Not sure what else could be done with brass prep to help this issue. All brass was fired 2x and redding body sized and Lee Collet Neck sized. Mouth of case was deburred and cleaned using inside neck cleaning brush. Brass was sorted by neck wall thickness and neck runout into my current batch. I measured 5 bullets to the ogive and all were same. Then when I seat my bullets no 2 come out the same. Die is adjusted properly unless something internally is messed up with the die(I cleaned the inside of the sliding sleeve prior to use)

 

[savageshooter86]

Off to Forster the brand new die goes

Wanted to post my outcome of this

Well the die is on it's way back to Forster. Still having problems with consistancy of seated bullets. Something is not right and was on the phone with Forster for about 30 minutes and with a fellow reloader on site for about 1 hr( we walked through set up and even disassmbled the die completely to work through evreything) trying to figure it out. NO LUCK. I set the die up and seated 5 rounds and get 5 different readings. Varying as much as .0095".

Press is the Lee Breech Lock and not even 1000 rounds through it. Everything on it appears tight and no slop in it. Everything on the die is tight and secure.disassembled entire thing and made sure nothing was suspect and reassembled. Brass has all been fired 2x and processed exact same way. Same neck wall thickness and neck runout and all necks even measured the same using my calipers to quick reference(.331")

All bullets had same ogive measurement prior to seating. Also we came up with the idea to seat 5 bullets that I measured the bullets to metplat to find 5 bullets with exact same length and seated those 5. Got same results(we thought maybe my hornady comparator was not performing properly). So measuring COAL from base of case to tip of bullet I was getting inconsistant readings too. My calipers are good, as I can measure length of brass or bullets over and over and get same reading. So we ran out of ideas.

So Forster wanted 5 bullets and 5 prepped cases and they are going to see what they can find. It is either the press or the die I believe at this point.

***I never encountered this using my old Lee seater die?***

 

[Elkbane]

Savagesgooter,
I'll be interested in the outcome of this also, but I think you're going to find out that it's not the die. IMO, here's why:

Think about the physics of what you are doing when you seat a bullet. You establish a fixed distance between the shellholder and a datum line equivalent to the ID of the seating stem by way of adjustments to the die (depth it's turned into the press and seating stem position).

As the bullet is seated, the case and bullet only have two points of contact: 1) at the case base (shellholder), and 2)on the bullet nose at the datum diameter (seating stem). You are tyring to measure a result (seating depth to ogive) based on parameters (bullet ogive length) that are not involved in the process. All other factors being equal, what determines how "deeply" a bullet is pushed into the case is the POSITION on the bullet nose where the diameter is equal to the ID of the seating stem cone. If you have variability in the SHAPE of the bullet NOSE, then you will have variability in seating depth, pure and simple.

You can have two bullets with identical length to ogive measurements, but if the shape of the nose is different, they will seat to different depths. You can confirm this for yourself by using a .22 cal or .17 cal insert in your comparator (something closer to ID of seater stem cone ) on test set of bullets with similar length to ogives for your intended caliber. My guess is that's the source of the variation you are experiencing.
Elkbane

 

[savageshooter86]

well if that's the case then these Hornady bullets are junk but have not read anyone else having these issues. Well good thing, like Forster tech said and other member, is that atleast once they get it we can figure out the cause. I too am ready to find out what the heck is going on.

Your post makes sense. But I still don't get how with the same batch of bullets using my Lee Seater Die once I adjusted it I was getting same readings everytime

 

[TOBY]

I agree with Elkbane. I have tried Sierra Match Kings all the way to Wideners bulk .308's and checked all of the same things suggested here All i can find is that the bullet nose conture varies in all that i have tried. Would like to find a solution but don't know where to go next. I am fairly new to reloading and joined this forum to find answer to this. I thought it was my lack of experience but see i'm not the only one with this problem. Am I being too technical and forget about it or what? Thanks

 

[jlow]

Neck tension is more than just that 0.003” number you give. It will include consistency in neck thickness (this is the reason for turning necks), springback i.e. how work harden (number of firing) the brass is, and how consistent you anneal your brass. For seating, chamfering your neck and how clean and smooth the neck is will also affect seating back pressure. Think of it this way, you are pushing a bullet into a tight neck and anything that affects how much and how consistent it resist the push will affect your final seating depth. If done correctly you should be able to get seating depth consistency in the 0.001” range.