Seating Depth Inconsistency

[savageshooter86]

Here is my current set up: Forster CoAx press, Lee RGB 223 Die Set, 1x fired Remington 223 brass, Hornady 55gr SP w/c, Hornady measuring tool with 22 cal insert. Seating die was set to apply the built in roll crimp from that seating die. Per the instructions

I loaded 25 rounds the other day and was getting very inconsistent OAL readings off of the ogive using the insert. Brass was all trimmed to 1.740" and chamfer/deburred. Is that most likely the die or what? Brass being 1x fired should not be having any issues with work hardening

 

[JASmith]

Ask yourself questions about the consistency of your equipment and techhnique?

For example:

• Does the measuring tool contact the bullet at the same location as does the seating punch?
  
• How consistent is your seating stroke? Do you bring the handle all the to the stop with the same force each time?

That will help your troubleshooting and help folks focus on the things that might be changed.

 

[jonbearman]

It is your seater stem more than likely.If you can get to a lathe,drill it out slightly bigger than the bullet nose ,then add epoxy to the hole and screw the stem in as far as possible and seat a bullet first without the epoxy and then epoxy(got ahead of myself) making sure you use mold release on everything you dont want it to stick to including the bullet.Engage the seated bullet and that will sqezze out the unwanted epoxy and let it sit till it hardens enough you cant stick a toothpick into it and retract the ram and you have a stem just for that bullet nose.After you are done redrill the hole out slightly so it doesnt interfer with bullet jackets that are not perfectly the same.IMHO only.

 

[gotcha]

Sav. 86, I like Jons idea and have used it myself successfully tho' not with Lee seater. I'd suggest you 1st remove the O-ring from the Lee lock ring then remove the O-ring from the seating stem & wrap the seater threads w/ Teflon tape to assure seating stem threads are not "floating" vertically in the die. ............... For my .223 loading I ended up buying the excellent Dillon .223 seater. thick stem, tight threads very consistent seating depth & concentricity....... Also, try seating a few rounds w/o crimp.

 

[mikecr]

I don't understand why you would crimp necks you're trying to seat well in.

 

[lpreddick]

learned this from this site...neck tension variation will affect bullet seating depth when measured off ogive. a tight neck resist bullet seating and the bullet will actually wedge itself into the seating stem .001-.002 or more while a loose neck will allow the bullet to seat when it barely touches the lip of the stem and this bullet measures seated .002-.003 DEEPER than the others. most stems i'v seen are hollow to allow any and all bullets to enter the stem. the idea of filling this hollow part so that there is full tip/ogive contact is a good idea. the other suggestion i saw was if a bulet seats tight and measures .002 longer , lower the ram, wait a few seconds and reseat and many times the bullet will seat to the same depth, although it will have tighter neck tension and could affect accuracy. i believe somebody called this "double seating".

 

[treeman]

annealing case necks will help get more consistent seating depths. accuracy will also be more consistent

 

[s100whunter]

Some of the inconsistancy can come from the cartrige head.After trimming on LE Wilson trimmer I turn the case and trim the head you will see a lot of variaction,one side will be high on Lapua the primer pockets will be high,this has helped with my seating depth

 

[mikecr]

annealing case necks will help get more consistent seating depths.

I don't think this is true.
Bullet grip(tension) equals springback.
When you size down a softer/annealed neck, it springs back outward less, leaving a greater interference fit. This means the bullet has to upsize the neck more on seating, and bullets make terrible expanders. Greater upsizing means greater friction, higher seating forces, and bigger seating depth variances. Another affect is that the reduced springback(from expansion) leaves lower grip on the bullet, so:

accuracy will also be more consistent

this only holds if you develop loads with softer necks and keep them at this state through continued and very precise annealing cycles.
I wouldn't attempt it with lower precision than a lead dip, and so I wonder(to myself) where the benefit is in it to begin with.

Well there is no benefit in it for me, because my sizing is not so gross that annealing(beyond initial) will ever be needed. My seating forces as measured haven't been changing, and my seating depths are spot on (not plus or minus anything).

Why do you think annealing provides an answer to seating challenges?

 

[lpreddick]

re annealing: work hardened brass is harder and more resistant to sretching when seating a bullet. this resistance pushes the bullet into the seating stem and the ogive measurement is long. annealing does soften the brass and the neck will stretch more easily and bullet does not enter stem and ogive measurement is longer. variations in neck wall thickness(not an issue with lapua), even if annealed and sized with a bushing will have varying resistance to seating and could result in varying measurements off ogive. a neat test is to size a case .001 smaller than another and seat same bullet with one pass and measure off ogive...smaller neck diameter is usually longer...there are exceptions. i'v done this, then shoot them and groups are different, often small but fraction apart.

 

[mikecr]

You're missing springback, the last action brass always takes.
When you down size annealed necks they spring back outwards less, leaving annealed necks smaller from downsizing than non-annealed neck downsizing. These smaller necks would then have to be expanded more by bullet seating, unless you're expanding with a tool(which I recommend). Friction can also be normalized, but a declaration that annealing alone improves seating amounts to a stretch in reality.
If no action is taken to counter the affects of annealing, especially variance in annealing, seating precision and consistent neck tension can worsen.