Mandrels expanders and different efforts

[ChuckSwagger]

We had discussed about use mandrels after the resizing the brass to uniform the bullet seating.
I was doing this now on new Lapua Brass (unfired) and have noted some brass I needed to use less effort to introduce the mandrel so I assume those brass will have less neck tension too.
How do you deal with?
Shoot the ammo and separated the brass which have the same velocity?

 

[whatsupdoc]

By introducing the mandrel into the neck you are or should be expanding the neck to a more uniform size than before.
The variation you feel may be the variation of the necks themselves or where the mandrel passes the neck shoulder junction.

Did you resize the brass first or just push the mandrel through?
With the bullets seated will the bullet bearing surface be at or past the neck shoulder junction?
You can push the mandrel in twice.

I would not worry about it until the brass has been fired, then see how the necks feel.

 

[ChuckSwagger]

The variation is in the beginning and mid thru.
I resize the brass first.

It has been strange, despite I got a SD of 10, i have velocities 2709, 2710, 2706 one in 5 te velocity goes to 2758, 2738, 2749.

I weight my bullets, size them, use a Autotrickler with exactly same powder charge, shoulder an brass sizes, neck turned...

Despite the groups being .5 and .4 groups I can't perform one hole group because there arealways some fliers

I think the problem is the piece behind the rifle.

 

[AZgeek]

Is a mandrel an alternative method to a neck bushing sizing die? Do they not both do the same thing? Is there and advantage to one over the other?

 

[whatsupdoc]

Is a mandrel an alternative method to a neck bushing sizing die? Do they not both do the same thing? Is there and advantage to one over the other?

A mandrel is a tool that gets pushed into the neck after resizing to expand the neck for the desired bullet tension.
It does the same thing as the expander button that comes with a resizing die but is pushed in instead of pulled out.

 

[whatsupdoc]

The variation is in the beginning and mid thru.
I resize the brass first.

It has been strange, despite I got a SD of 10, i have velocities 2709, 2710, 2706 one in 5 te velocity goes to 2758, 2738, 2749.

I weight my bullets, size them, use a Autotrickler with exactly same powder charge, shoulder an brass sizes, neck turned...

Despite the groups being .5 and .4 groups I can't perform one hole group because there arealways some fliers

I think the problem is the piece behind the rifle.

LOL, everybody wants one hole groups but few are good enough to shoot them. Dont stress too much on the crono numbers the holes on the target are the final report card.

 

[AZgeek]

A mandrel is a tool that gets pushed into the neck after resizing to expand the neck for the desired bullet tension.
It does the same thing as the expander button that comes with a resizing die but is pushed in instead of pulled out.

I take it the expander ball pulling out is rougher on the brass, more inconsistent that using a mandrel?

 

[whatsupdoc]

Not rougher on the brass, it seems that a mandrel pushed into the case neck produces less runout on the neck than a conventional
dies button expander being pulled out.
This is not always the case though, sometimes the standard expander ball will do just as well as a mandrel.

 

[b2lee]

My take...so take it for what it is worth:

Some sizing dies with an expander ball put the ball on the very end of the spindle and use the ball to retain the primer pin.....after some use this setup will bend the ball at an angle or bend the spindle. This isn't good for neck tension consistency.

I use a neck bushing die in a LE Wilson arbor die....this sizes the outside of the neck...however...I run them through a neck mandrel afterwards because I want the inside of the neck to be perfect and move the .001 or .0005 variance in neck wall thickness to the outside of the brass where up expansion may not make a bit of difference.

I also use the neck mandrel to get a feel for variance in neck tension...when I find a piece that is notably stiffer than the others...it goes to the side....probably was a piece that was either not annealed at the same time as the rest...or has some other variance.

When we are shooting mile plus ranges....you gotta sweat the small stuff.

 

[whatsupdoc]

A mandrel will not change or correct neck wall thickness variation, only neck turning or some type of machining will correct that.

 

[Sig Marine]

Brass has springback. New brass is inconsistent in neck diameter/tension and therefore the springback will be inconsistent...even if using a mandrel. This is why fired brass is more consistent...you have made the necks basically the same diameter by forming them to the diameter of your chamber's neck dimension. Now when you size (or size and mandrel), all the brass will have a more consistent springback and diameter resulting in a more consistent neck tension.

 

[Dthomas3523]

LOL, everybody wants one hole groups but few are good enough to shoot them. Dont stress too much on the crono numbers the holes on the target are the final report card.

Definitely stress about numbers on chrono. Going from 2710 to 2758 is about a 1moa difference @1k.

Can’t beat physics. That’s what dictates where the holes on the target show up.

 

[Mgordon]

While testing our new Precision Resizing Dies and "The" Seating Die we did some very limited testing. We started off with 20 rounds of 6 BRA fired brass and sized it all with our new resizing die with a .266" neck bushing. 10 pieces were left full length sized with a neck bushing, no expanding. The other 10 pieces were full length sized using the same neck bushing but we expanded up with a 21st Century expander mandrel set, .2415". Then we measured the neck runout on both batches, then we seated a bullet and measured the bullet runout.

The full length sized with neck bushing only ammo had less neck runout and less bullet runout. It averaged .0007" less bullet runout and .0003" less neck runout than the sized and then expanded ammo.

Again, this was a very limited test and we intend on doing a lot more testing as time permits, but it is worth considering which is more important: Bullet runout, or more consistent neck tension? That is the million dollar question.

I'm leaning toward bullet runout at this point because it is a mechanical misalignment of the bullet to the bore and I believe that a proper charge weight (Optimal Barrel Time) node can soak up some discrepancies in pressure. Again, this is just a "gut" feeling, we have more testing to do.

Mark.

 

[whatsupdoc]

Here is some more wood for the fire.

For case/bullet combinations where the bullet bearing surface reaches the neck shoulder junction neck tension variation
can become a problem.

I noticed that on some cases after full length resizing and pushing a mandrel into the neck, seating bullets required different amounts of force and the CBTO would vary. Checking with a pin gauge I found that the pin gauge would fit in the neck but would stop or get very tight at he neck shoulder junction.
This tight spot was causing seating inconsistency.

Pushing the mandrel through twice or three times ironed out the constriction and improved the seating consistency.

I realized that the brass (various brands) that had this issue had been reloaded many times so I wondered if my annealing was not working properly.
Using my home made induction annealer I started increasing the anneal time and sure enough the the constriction at the neck shoulder junction was greatly improved.

 

[Tokay444]

A mandrel will not change or correct neck wall thickness variation, only neck turning or some type of machining will correct that.

This true, but the theory is that the mandrel will move those inconsistencies to the neck OD, where they should matter less. Not eliminate them all together.

Here is some more wood for the fire.

For case/bullet combinations where the bullet bearing surface reaches the neck shoulder junction neck tension variation
can become a problem.

I noticed that on some cases after full length resizing and pushing a mandrel into the neck, seating bullets required different amounts of force and the CBTO would vary. Checking with a pin gauge I found that the pin gauge would fit in the neck but would stop or get very tight at he neck shoulder junction.
This tight spot was causing seating inconsistency.

Pushing the mandrel through twice or three times ironed out the constriction and improved the seating consistency.

I realized that the brass (various brands) that had this issue had been reloaded many times so I wondered if my annealing was not working properly.
Using my home made induction annealer I started increasing the anneal time and sure enough the the constriction at the neck shoulder junction was greatly improved.

This is why you don't want to seat your bullet's bearing surface into the neck/shoulder junction.

 

[hollywood1981]

I use my mandrels after fl resizing with bushing dies. Also with virgin brass

 

[Formosan]

Here is some more wood for the fire.

For case/bullet combinations where the bullet bearing surface reaches the neck shoulder junction neck tension variation
can become a problem.

I noticed that on some cases after full length resizing and pushing a mandrel into the neck, seating bullets required different amounts of force and the CBTO would vary. Checking with a pin gauge I found that the pin gauge would fit in the neck but would stop or get very tight at he neck shoulder junction.
This tight spot was causing seating inconsistency.

Pushing the mandrel through twice or three times ironed out the constriction and improved the seating consistency.

I realized that the brass (various brands) that had this issue had been reloaded many times so I wondered if my annealing was not working properly.
Using my home made induction annealer I started increasing the anneal time and sure enough the the constriction at the neck shoulder junction was greatly improved.

Very interesting.

How much time and money did you invest into your induction annealer? Your own design or did you have schemes?

 

[bfk4lyfe]

how much smaller a bushing do you guys typically use than your mandrel size, if using a mandrel to set final neck tension?

 

[Sokam101]

how much smaller a bushing do you guys typically use than your mandrel size, if using a mandrel to set final neck tension?

I went away from a bushing die. To much stress on the neck pushing it down and mandreling it back out. From what ive heard the is the biggest weak point of brass.

 

[Tokay444]

how much smaller a bushing do you guys typically use than your mandrel size, if using a mandrel to set final neck tension?

I run a bushing that gives me .005” neck tension and then a mandrel to set either .002” or .003” neck tension. Works. Out of six shots, only 2 weren’t the same speed

 

[ChuckSwagger]

With new brass I still feel diferences when I am seating bullets, even using mandrel expander or bushing either.
I weight my bullets and measure its length.
Using SMK 168gn I have 2709, 2012, 2008, but there are someones who are way more elastic as 2734, 2742, and ruins my shoot strings.
Now I will try to short the brass from its shooting velocity.
I use the autotrickler, 44,2gn de Varget, CCI BR2 primers, Lapua brass, 0,020 from the lands.
It is driving me crazy!!!

 

[memilanuk]

I run a bushing that gives me .005” neck tension and then a mandrel to set either .002” or .003” neck tension.

It'd be interesting to take some pin gauges and see what the final ID actually ends up as, with brass spring back and all.

 

[Tokay444]

It'd be interesting to take some pin gauges and see what the final ID actually ends up as, with brass spring back and all.

No problem.

 

[beetroot]

I run a bushing that gives me .005” neck tension and then a mandrel to set either .002” or .003” neck tension. Works. Out of six shots, only 2 weren’t the same speed View attachment 7436525
View attachment 7436526

What are you using to weigh your powder?
I imagine consistent neck tension helps with ES/SD but you need to have the rest of the process equally as consistent.

 

[memilanuk]

it is worth considering which is more important: Bullet runout, or more consistent neck tension? That is the million dollar question.

I'm leaning toward bullet runout at this point because it is a mechanical misalignment of the bullet to the bore and I believe that a proper charge weight (Optimal Barrel Time) node can soak up some discrepancies in pressure. Again, this is just a "gut" feeling, we have more testing to do.

Mark,

It'll be interesting to see what kind of results your testing bears out. I've always kinda subscribed to the theory that a lot of concerns over TIR are perhaps a bit exaggerated, at least in the context of a 'match' chamber. As an example... for a .308 Win, most match chambers have a freebore diameter of .3085". Whatever the TIR is going in, that half thou is about all there is room for once the round is in the chamber. I realize it's certainly less than ideal to be jamming crooked rounds into a chamber and depending on the barrel steel to straighten things out... but in practice, it seems to work out that way. Maybe in 'looser' SAAMI chambers, with a more generous freebore diameter, things may be entirely different. Again, just a 'theory'... and not even originally 'mine', FWIW.

I noticed that on some cases after full length resizing and pushing a mandrel into the neck, seating bullets required different amounts of force and the CBTO would vary. Checking with a pin gauge I found that the pin gauge would fit in the neck but would stop or get very tight at he neck shoulder junction.
This tight spot was causing seating inconsistency.

Pushing the mandrel through twice or three times ironed out the constriction and improved the seating consistency.

That... sounds an awful lot like you had a donut forming at the base of the case neck, and 'ironed' it out (transferred it to the outside of the case) using the mandrel. I've also heard of people using a pin gauge, with a sharp corner to kind of knock or shear off the donut as well.

 

[Tokay444]

What are you using to weigh your powder?
I imagine consistent neck tension helps with ES/SD but you need to have the rest of the process equally as consistent.

I throw on a Chargemaster 1500.

 

[308pirate]

Here is some more wood for the fire.

For case/bullet combinations where the bullet bearing surface reaches the neck shoulder junction neck tension variation
can become a problem.

I noticed that on some cases after full length resizing and pushing a mandrel into the neck, seating bullets required different amounts of force and the CBTO would vary. Checking with a pin gauge I found that the pin gauge would fit in the neck but would stop or get very tight at he neck shoulder junction.
This tight spot was causing seating inconsistency.

Pushing the mandrel through twice or three times ironed out the constriction and improved the seating consistency.

I realized that the brass (various brands) that had this issue had been reloaded many times so I wondered if my annealing was not working properly.
Using my home made induction annealer I started increasing the anneal time and sure enough the the constriction at the neck shoulder junction was greatly improved.

That's the neck donut. First I read about it was about 20 years ago when David Tubb was developing the 6XC

 

[Gustav7]

That's the neck donut. First I read about it was about 20 years ago when David Tubb was developing the 6XC

How/Why does it form? Can it be avoided?

And if you do get it or have it, is a multiple mandrel run the only real option?

 

[Tokay444]

You can ream it out.
Certain case designs are more susceptible to. It’s from pushing material down the neck into the neck/shoulder junction.

 

[b2lee]

How/Why does it form? Can it be avoided?

And if you do get it or have it, is a multiple mandrel run the only real option?

It also happens if you neck turn your brass..and you don't go down the neck far enough...hence why you go into the shoulder a little bit. Reamers work great....but if money is no object... I recommend the IDOD Case Turner

 

[308pirate]

@Gustav7 other guys beat me to the punch.

From what I know of your reloading process, you don't need to worry about it.

 

[HellcatActual]

I run a bushing that gives me .005” neck tension and then a mandrel to set either .002” or .003” neck tension. Works. Out of six shots, only 2 weren’t the same speed View attachment 7436525
View attachment 7436526

thats impressive reloading skills sir

also - watch your MS cable. starting to fray at the jack end.

 

[Jackomason]

when your mandrel die is installed in the press with out the mandrel, should the case sit centered in the die body or will it have a bad effect on concentricity if its not?

 

[Tokay444]

thats impressive reloading skills sir

also - watch your MS cable. starting to fray at the jack end.

Yeah, that telescoping cable is available at the dollar store. Magnetospeed ships with that and a beefier one.

 

[HellcatActual]

Yeah, that telescoping cable is available at the dollar store. Magnetospeed ships with that and a beefier one.

my retractable cable didnt fair too long. now its just a long cable with a dangly thing in the middle

 

[bfk4lyfe]

my retractable cable didnt fair too long. now its just a long cable with a dangly thing in the middle

If its not retracting, try backing out the screw and fiddling with it, mine does that every so often.

 

[NiteQwill]

when your mandrel die is installed in the press with out the mandrel, should the case sit centered in the die body or will it have a bad effect on concentricity if its not?

Most mandrel dies are "floating." So unless your press is off, the mandrel should find the center.

 

[memilanuk]

Most mandrel dies are "floating."

Except K&M... unless you float the die body itself, or use a riser window and a Co-Ax press.