Question about Porters mandrals and die

[TommyD11730]

So today I recieved my Porters products collet die and mandral assortment. Just so happened I have some brass that I full length resized without the expander ready to go. (Done on a Foresters FL NON bushing die). I checked the runout on the necks and was getting arount .001 runout.
So I setup my die, selected my mandral to give me .0015 neck tension and away I went.
Checked the 1st round and the tension was right on. Checked the next few and again perfect.
So I ran 25 or so cases, pulled out my runout gauge and nearly fell off my stool.
Good cases are now about 003 runout. Bad ones are 005!
So, someone educate me. The process I thought went smoothly. Little lube, and not much effort running the press.
Could it be I have to take smaller bites and say set the tension to .003 first, then down to .0015?
Lapua 308 brass if anyone is interested.
Thanks!

 

[Baron23]

So today I recieved my Porters products collet die and mandral assortment. Just so happened I have some brass that I full length resized without the expander ready to go. (Done on a Foresters FL NON bushing die). I checked the runout on the necks and was getting arount .001 runout.
So I setup my die, selected my mandral to give me .0015 neck tension and away I went.
Checked the 1st round and the tension was right on. Checked the next few and again perfect.
So I ran 25 or so cases, pulled out my runout gauge and nearly fell off my stool.
Good cases are now about 003 runout. Bad ones are 005!
So, someone educate me. The process I thought went smoothly. Little lube, and not much effort running the press.
Could it be I have to take smaller bites and say set the tension to .003 first, then down to .0015?
Lapua 308 brass if anyone is interested.
Thanks!

My friend, I'm def no machinist or gunsmith, but runout gauge? You are measuring on the outside of the necks while rotating the case? Or looking at concentricity on the inside??

I'm not sure how you are using it or what you are finding.

I use pin gauges to measure neck tension...and again, I'm no machinist. But what I'm interested in is I.D. compared to the O.D. of the bullet's bearing surface. I have an assortment in .0005 increments. And, I just use FL dies with an expander ball so I'm def no BR precision reloader.

Since you have a mandrel assortment, have you tried to hand fit mandrels into the neck (after sizing) and see exactly what you have for an I.D.?

And, I may be far off base so please forgive me if I'm spreading misleading info.

Cheers

 

[TommyD11730]

My friend, I'm def no machinist or gunsmith, but runout gauge? You are measuring on the outside of the necks while rotating the case? Or looking at concentricity on the inside??

I'm not sure how you are using it or what you are finding.

I use pin gauges to measure neck tension...and again, I'm no machinist. But what I'm interested in is I.D. compared to the O.D. of the bullet's bearing surface. I have an assortment in .0005 increments. And, I just use FL dies with an expander ball so I'm def no BR precision reloader.

Since you have a mandrel assortment, have you tried to hand fit mandrels into the neck (after sizing) and see exactly what you have for an I.D.?

And, I may be far off base so please forgive me if I'm spreading misleading info.

Cheers

Thanks for the reply.
Its been a long day, so im sorry for not being clear.
Im using a Sinclair tool and yes it meadures the concentricty of the outside of the brass.

Also forgive me as the Porters tool uses gauge pins vs a mandral to open the neck up.

Granted I cant measure the concentricty of the inside of the neck. However I have to wonder, if it is straight and true why is the OD concentricty worse after resizing?

 

[Cascade Hemi]

Is your brass turned? Have you mic'd the necks with an tube mic?

 

[TommyD11730]

Is your brass turned? Have you mic'd the necks with an tube mic?

No neck turning.
No tube mic.

 

[Cascade Hemi]

No neck turning.
No tube mic.

I'm sure you probably did have some run out but even Lapua necks aren't completely uniformed thickness. The mandrel pushes all of the neck irregularities to the outside so what ever runout you measured was compounded.

With that said, my experience with the Porter mandrel is that it functions just like the other brands and isn't any more or less concentric. You may take a look at the pins and make sure there isn't any galling. Also, depending on the thickness of the brass and the ID of the die neck, you may be sizing up the brass a lot.

 

[Tokay444]

Runout of bullet is what you need to measure.

 

[Baron23]

Thanks for the reply.
Its been a long day, so im sorry for not being clear.
Im using a Sinclair tool and yes it meadures the concentricty of the outside of the brass.

Also forgive me as the Porters tool uses gauge pins vs a mandral to open the neck up.

Granted I cant measure the concentricty of the inside of the neck. However I have to wonder, if it is straight and true why is the OD concentricty worse after resizing?

Wow, I would def take input from other more experienced reloaders who replied than I, but I'm kind of with @Cascade Hemi ......a bit of uneven wall thickness and some O.D. run out wouldn't concern me (as long at these necks when into my chamber cleanly) and I would be concerned about I.D. which you have set and...hopefully measured with your pin gauges....for the neck tension you want.

For me, neck turning (normalizing the thickness of the neck) is for BR and other reloaders who are deeper into the details than I and my purposes for reloading.

I'm not sure you have an actual performance effecting problem at all but sure other more expert opinions will be offered.

Have you shot this stuff at all? Chrono'd and looked at speed and group consistency?

Best of luck...oh, and I think that the only diff between a pin gauge and a mandrel made for neck sizing is that the mandrel has a chamfer on the end to make it easy to insert into the case. But I'm willing to be corrected on this also.

 

[TommyD11730]

Another long day. Just wanted to thank all you guys for chiming in.
So.. im sitting at the bench. 50 Now primed Lapua cases in front of me. Tommorow Ill drop a charge and seat some bullets. Friday will be range day. 1st time with the Porters die and their pins.
I had a few rounds here I made a few weeks back. This was on a Forsters full size die with their expander mandral. This brass measured a loaded run out on the necks from .002 to .004. However when I checked loaded bullet runout im seeing .004 to .010 .
Ill measure the runout on the Porters prepped cases tommorow.
Again thanks for the imput guys.
Tommy D