Neck expanding

[mitchellchandler_au]

Hi all,
I was just wondering who uses an expander mandrel to set the final neck diameter before bullet seating. I was interested to know what procedure is used and what tools are used. I have always just used dies with neck bushes so I know bugger all about expander mandrels.
Thanks for the reply's.

[6.5x55ai]

i have gone away from using my Redding Comp dies with bushings, likewise my Redding Body dies and also a Whidden FLSing die with bushing. I just could never get satisfactory runout. The Body die was the worst, in part I think because the neck is unsupported whilst sizing.
For a period I used Lee Collet dies which gave very minimal runout but didn't solve the issue of full length sizing.

For some time now my process has been anneal fired case, FLS with Forster FLSing die with expander removed, expand using 21stCentury Mandrel.
I have a range of mandrels (refer BRT) so can fiddle with neck tension.
So, the benefit of how I do things now is much reduced runout and better control of neck tension. No more neck turning to get optimal results with bushings etc.
My runout now is generally around 1thou. (Then of course there is the discussion around if runout is an issue....)

[Downes Equestrian]

I'm running tight necks in both my rifles, so I have to use collet dies and an expander mandrel to set neck tension (yep, I know that gives a linear measurement not a measurement of force/tension) at 2 thou. so, depending on how much I neck turn my cases I then select a collet and expander to suit. K&N have a range of expanders that go up in half thou increments. I also use gauge pins to ensure that after brass spring back that I'm achieving the dimensions I need. I use a force gauge when seating projectiles on an arbor press. I'm running Wilson dies.
seems to work very well.

[MarkS]

Every guy I know that hand loads for competition uses an expander mandrel to set final neck tension.
You still use your resize die after firing.
Expander ball, if there is one, is always immediately removed from resizing die on initial setup.
ES/SD is always significantly better with this brass prep system.
21st Century Expander Die Body with 21st Century undersize mandrels(for whatever caliber you are loading)
Check out the legends at BRT Shooting Supplies
Example for say 6mm;
https://www.brtshooterssupply.com.au/pr ... ess-steel/

You would need to provide more info such as are you annealing, what brand of brass, etc to offer more ideas.

[PeteFox]

Mandrel dies are all about 2 things, runout and consistent neck tension. but they are not the solution by themselves.

Use a decent quality sizing die in a press that is capable of maintaining alignment under the stress of resizing, where the threads aren't made like the wheel studs on your box trailer and the die is down tight with a lock ring that is square to the axis of the die. No shooter is going to have the equipment to measure all this so you have to rely on the manufacturer not cutting corners - if it is mass produced then you get larger tolerances and stacking tolerances (e.g. wobbly thread + lousy die + misaligned threads) will kill accuracy.

I am using Porter Precision https://portersprecisionproducts.com/mandrel-dies/ mandrel dies . Instead of a floating mandrel like 21st Century and others, they use a gauge pin held in place with a collet, the same setup as an end mill holder. At present I'm using a .2835 minus pin for .284.
The runout I'm getting with this setup is always less than 0.001", I've given up checking and the $300 checking tool is wasted. if you want to go to this level you need to ditch the expander ball for something better

Consistent neck tension is dependent on a number of things; all of the following need to be consistent:
Consistent brass hardness and elasticity - annealing required
Consistent brass thickness - thicker brass will have more clamping force, variation between individual pieces of brass = inconsistent grip - so necks need turning to achieve this
Consistent neck friction - lubrication needs to be present and evenly applied, inside neck finish needs to be consistent, don't clean brass in harsh chemicals that will etch the brass.
Consistent neck sizing - thats what the mandrel is for.

You might think that this is over the top bull shit, and it might be, but my OCD won't have it any other way. None of these alone are probably much of an accuracy killer, but get a few wrong on one round and that might be the 4 at six o'clock.

Pete

[6.5x55ai]

Peterfox- I have a mixture of 21stC, K&M and Porter expander systems. The Porter stuff is precision made and he was great to deal with. The only issue I find is the mandrels would be better with more taper. If expanding a lot in one step I get runout. My sizing die sizes quite considerably (which does work the brass more than optimum but I do anneal). Because I then need to expand quite a bit I have found that with the Porter I need to expand in 2 steps. Fortunately when I purchsed his product I bought a complete range of mandrels.

One of the advantages of the Porter mandrels is I can make my own out of easily available pin gauges.

[PeteFox]

Peterfox- I have a mixture of 21stC, K&M and Porter expander systems. The Porter stuff is precision made and he was great to deal with. The only issue I find is the mandrels would be better with more taper. If expanding a lot in one step I get runout. My sizing die sizes quite considerably (which does work the brass more than optimum but I do anneal). Because I then need to expand quite a bit I have found that with the Porter I need to expand in 2 steps. Fortunately when I purchsed his product I bought a complete range of mandrels.

One of the advantages of the Porter mandrels is I can make my own out of easily available pin gauges.

I don't think we are talking about the same thing, i'm talking about final expansion of the neck after passing through the full length bushing die, this is in the order of .001". not much scope for 2 steps there. If you are expanding after FL sizing enough to need two steps then I think your die setup may be the issue creating a need for two step expanding.

If you are talking about expanding necks to a different calibre then I agree, more steps is better but tedious. I have found that in expanding new brass, say from 6.5-284 to 30-284, I do that in 2 steps and then full length resize to remove runout. Doing it in one step significantly distorts the case, rounds the shoulder area and makes chambering difficult. I have recently purchased the Cortina micro sizing dies that resize the entire length of the case (not just the shoulder area) to restore alignment.
Pete

[6.5x55ai]

Ah no, the same thing virtually, No, I didn't mention expanding to another calibre as in 6.5 to 284.
Our only difference is I no longer use FLSing bushing dies (be that my Wilson bushing die or Whidden). I now use a Forster FLsing die without the expander. Forster for their price point probably make one of the most dimensionally correct dies. The downside is they size close to minimum SAAMI likewise the neck is worked quite a bit and needs more than 1 thou expanding. (The Forster need custom honing and it would be perfect.) Currently though, sizing in one step with the Porter induces runout. Sizing with the equivalent sized 21stCentury mandrel and no runout. What can the difference be? The 21st Century has more taper and floats in its holder, the Porter has a sharper taper and is held rigid in the collets. My neck chamfers are perfect. I have had a mate grind one of the Porter mandrels, which are essentially a pin gauge, with more taper, or taper similar to the 21stC and the K&M, and the Porter no longer induces runout.

[mitchellchandler_au]

So I have a few of the k and m expander mandrels, the 1.5 and 2.5 under size. I use an AMP annealer before sizing. I use a wilson FLS die with the lapua and alpha munitions brass. My main reason to try the mandrels is with a 208 ELDM seated to touch the rifling the shank of the projectile is flush with the neck shoulder junction. I was concerned about doughnuts forming and this seems the best way to keep them from being on the inside of the neck. I hope my reasoning makes sense.

[PeteFox]

So I have a few of the k and m expander mandrels, the 1.5 and 2.5 under size. I use an AMP annealer before sizing. I use a wilson FLS die with the lapua and alpha munitions brass. My main reason to try the mandrels is with a 208 ELDM seated to touch the rifling the shank of the projectile is flush with the neck shoulder junction. I was concerned about doughnuts forming and this seems the best way to keep them from being on the inside of the neck. I hope my reasoning makes sense.

Personally, I think that this is a bad idea. It might be perfectly safe to do in your rifle, then again it may not.

So the donut is getting displaced to the outside of the case, this must enlarge the case at the neck-shoulder junction, bullet is fitted and then you close the bolt on it. Depending on clearance, don't you think it's possble that you are now clamping the bullet using the bolt.
Isn't using a mandrel to displace the donut the same as using the bullet to do it - the very thing you were trying to avoid.

Better to use an inside neck reamer or possibly outside neck turn after using the mandrel to remove the brass, but I haven't tried it
Pete

[mitchellchandler_au]

Hi pete,
I also have an inside neck reamer to cut out any doughnut if one starts to form. I wouldn't think it will remove all of it so once it is pushed to the outside it hopefully wont cause it to pinch the bullet. Obviously using a bullet that seats further out will solve all the problems but I wanted to see how people use the mandel.

[ned kelly]

G'day All,
regarding donuts, I use the LE Wilson reamers to cut them out of the shoulder neck junction, BUT I use a reamer 1 thou smaller than the bullet....I DONT want to cut into the neck turned cases.
And yes you can re-neck turn the cases if required and you will notice that in well used cases the brass has thickened as you approach the shoulder due to flowing under pressure.
Remember pressure acts equally in all directions and you will also find your primer pockets becoming shallower over time.
I noticed this in several 6PPC barrels as we only have 20-25 cases per barrel and the can easily be fired over 100 times until the barrel is finally retired from any form of competition.
No I dont anneal, the cases are always FLS with a small base FLS die and perfectly match the chamber for minimal resizing.
food for thought.....
Cheers Geoff