Mandrel flaring end of neck?

[dnellans]

Right - and thats why I tried some shot but not cleaned cases to see if those flared too without any carbon lube.  that "could" be it still potentially.  seems hard to believe that much carbon lube could build up but you never know.

The carbon I was referring to was carbon from previous firings, not the graphite lube.

Ah - gotcha.  I'm cleaning cases with stainless pins currently so the inside of the necks is pretty much stripped of any carbon and it would take a -lot- of lube to be equiv of the layer of soot that is in uncleaned cases.  i'm going to measure and see if there is any burr on the inside of the neck that the mandrel could be forcing out,  it also seems unlikely but none of this makes a lot of sense

[jvw2008]

Didn't know you were cleaning with SS pins, so that idea is out the window! ? I'm out of ideas! ?

[dnellans]

Didn't know you were cleaning with SS pins, so that idea is out the window! ? I'm out of ideas! ?

Appreciate all the help,  5 hands scratching heads is better than one!

[gman47564]

Just curious. Are you chamfering inside and out of necks before sizing or after.

[dnellans]

Just curious. Are you chamfering inside and out of necks before sizing or after.

after, because if neck isn't totally round chamfering gives shitty results.

my process is

pop primers, ss pin wash, anneal, (lube, body size, trim only when needed), polish in walnut, graphite em, bushing neck size, mandrel, chamfor in and out+ primer pocket clean up.

then prime, charge, load.

seem sane enough?

[gman47564]

yep.. just don't see how your process ca flare the neck out... does the mandrel pull through hard..

[Fuj]

Thanks for the thoughts all around guys,  will check all of this again tonight and see what the story is.

If it was extending beyond the bushing, then it should be flared before I put the mandrel down it, but its not, so I suspect that isn't the issue.  The fact there might be a ridge on the inside of the neck like Fuj mentions is certainly possible though.

Fuj - right now I neck, mandrel, inside/outside chamfor.  (This is assuming they don't need a trim, which is almost always).  Do you chamfor before running a mandrel in?  I wouldn't expect them to have a ridge on the inside of the neck but i'll pull a dental pick over a couple tonight and see if i can feel something.

I full length size in my custom chamber die. Neck was honed so that
there is no excessive movement of metal for the mandrel..... Cases
are then trimmed to length, chamfered and deburred. My chamfer
tool does both inside and outside. I usually take scotch bright to the
cases to remove any shavings, air blast, then to the mandrel die.....
The problem I had was from a dull cutter. The chamfer looked good to
the eye but, instead of a clean cut, the cutter left a rolled over edge
to the inside. I re-ground the cutter and also gave it a steeper angle.
It cured my problem.

[JASmith]

Have you checked case lengths?

I had a batch of in another 6.5 brass grow so long after more than ten reloads that the mouth was trying to push into the chamber throat.  Needless to say I got some interesting pressure signs.

The flaring might then have resulted from your cases having become a skosh longer than expected.

[MLN1963]

I have noticed this on my brass as well. I use a bushing die as well. I've noticed it with an expander ball and mandrel. I borrowed a buddies Lee collet style neck sizer and the flare went away.

It's not a chamfering issue. My thought is it has to do with elasticity of the brass and spring back. As the expander ball or mandrel is pulled out of the neck the brass pulls back to a smaller size. Since there is no brass past the lip of the neck it doesn't have the same amount of tension to bring it back to the same size as the brass below it.

As the expander is pulled through the brass its smaller on both sides of the ball. The top side because it was sized down, the bottom because of spring back making it slightly smaller the the expander. As the expander/mandrel leaves the neck the area at the opening doesn't have the same amount of brass to help pull it down in size. Not as much spring back. At least this is how I see it.

I live with it since it is a constant. I use the collet die if I need to check neck thickness as it makes sure I don't have the flare at the end.

[bikemutt]

I couldn't get satisfactory results with a bushing die, seemed like there was always something going goofy with the necks. Since I don't turn necks I took the lazy way out and went back to using a Lee collet die. For the kind of shooting I do the Lee die is good enough.

[gman47564]

I wouldn't trade one Lee neck sizing collet die for all the bushing dies that are out there. They just flat work as intended...

[jvw2008]

@dnellans:  what have figured out on this issue?

[rardoin]

@dnellans:  what have figured out on this issue?

Curious also....

One question- I note in your prep protocol you remark ..."graphite, neck sizing...".  Do you use graphite as your sizing lube for the neck bushing?  If so have you tried another lube for this step such as Imperial?

[Fuj]

Stepping back into my tool makers shoes, there may be another
occurrence, and that of the mandrel itself. A ball end mandrel
really does not have much of a taper so to speak. Speed of the
strike can vary a mouth flare. A slow, even push works best. A
mandrel with a steep taper and full 100% contact in the neck will
also always be better then a ball with minimum contact, thru the
stroke. Kind of like using a bullet, upside down to size the inside.
I'm a fan of the Lee collet die, but did make my own mandrel with
a steep taper, to get my .002 neck tension.

[icebug]

It seems that I'm facing the same issue on my 3+ times fired .308 Lapua brass.
I've noticed that the lip of the neck is slightly wider and that is happening right after bushing neck resizing.
My reloading procedure goes:
- decapping with universal decapping die
- SS wet tumbling
- NK or FL resizing (using TiN bushings - NK die or FL bushing die)
- inside chamfering
- priming, loading

Never bothered measuring what is the difference, but it's visible by naked eye.
Maybe the bushing goes too deep down the neck, allowing the lip to springback/expand as it exits up from the bushing?
Will try with bushing going shallower.