• Watch Out for Scammers!

    We've now added a color code for all accounts. Orange accounts are new members, Blue are full members, and Green are Supporters. If you get a message about a sale from an orange account, make sure you pay attention before sending any money!

sizing new brass

Neck size - always. No way to control neck tension otherwise. The bullet basically becomes an expander mandrel.

I want to say that brand new Lapua brass in the 308 flavor will give you nominally like .008 neck tension! A bit tight there...
 
I know what you mean. At least you shouldn't have to FL them or do any primer pocket cleaning. FL sizing is what sucks worse than anything in my opinion.

They do come way tighter than I'd typically like (and some random due to the dented case mouths during shipping). I run an expander ball through them, then transition them over to my Redding Competition bushing sizer die to end up at .002 - .003.
 
Last edited:
I chamfer new brass case necks and then just run them through an expander mandrel....gives me a perfect .002 neck tension. For me, I get less run out than using an expander ball this way
 
necks all beat up.. out of round.. guess the ups guy decided to see how much he could throw them around are something..???
 
necks all beat up.. out of round.. guess the ups guy decided to see how much he could throw them around are something..???

Unfortunate but yes, rough handling and/or poor packaging (can you say Midway, lol) really sucks. An expander mandrel will solve this kind of a problem much better than neck sizing alone. You want the "problems" pushed to the OUTSIDE of the case neck, not the inside.....
 
When you guys say you "run them over an expander mandrel" is that like going 2/3 into a FL Die?
I am imagining enough stroke that the case mouth goes up into the die and through the expander ball/button, but not all the way up into the die? Why not just use a neck die then? Or is it completely different than that?
 
I chamfer new brass case necks and then just run them through an expander mandrel....gives me a perfect .002 neck tension. For me, I get less run out than using an expander ball this way

Yeah, I've heard of that happening with the expander balls. I do have many mandrels as well that I use interchangeably (only on new brass - after that they are good to go with neck-sizing only). I actually take an approach above and beyond what most people would I think... I actually polish and impregnate the expander balls with Tungsten Disulfide in a small rock tumbler with aluminum BB's. I do it to neck-bushings as well. It only applies a .05 micron thick film that makes the surface ridiculously slick. It lasts for quite some time as well. Molybdenum Disulfide powder can be used as well. Ultimately I am relying on the bushing to do the sizing. The expander ball/mandrel is just to enlarge a tad.

I would imagine that if anyone wanted to do this also you could probably just do it in your vibratory tumbler perhaps. It's just another step to make that much less friction in the process overall.

Check out: https://www.ws2coating.com/blog/a-co...num-disulfide/
 
When you guys say you "run them over an expander mandrel" is that like going 2/3 into a FL Die?
I am imagining enough stroke that the case mouth goes up into the die and through the expander ball/button, but not all the way up into the die? Why not just use a neck die then? Or is it completely different than that?

Sort of. In your situation I would not buy more tools if you dont want to and just run them into the FL die as far down as I could without bumping the shoulders back any further as they are likely at the minimum side of saami spec. (provided the new brass chambers. If it doesnt you might have a super tight chamber and would need to bump them but thats for a <1% of the time situation) If you only go to the expander ball youll get your consistent neck tensions but you will possibly induce some runout/concentricity issues.

The expanding die is like the expander ball part of the die but a mandrel; a solid metal bar to round everything out and force the brass inconsistencies to the outside away from what grips the bullet.

http://www.accurateshooter.com/techn...-neck-tension/

https://www.youtube.com/watch?v=PA2U8WHHr9U
 
Last edited:
Yeah, I've heard of that happening with the expander balls. I do have many mandrels as well that I use interchangeably (only on new brass - after that they are good to go with neck-sizing only). I actually take an approach above and beyond what most people would I think... I actually polish and impregnate the expander balls with Tungsten Disulfide in a small rock tumbler with aluminum BB's. I do it to neck-bushings as well. It only applies a .05 micron thick film that makes the surface ridiculously slick. It lasts for quite some time as well. Molybdenum Disulfide powder can be used as well. Ultimately I am relying on the bushing to do the sizing. The expander ball/mandrel is just to enlarge a tad.

I would imagine that if anyone wanted to do this also you could probably just do it in your vibratory tumbler perhaps. It's just another step to make that much less friction in the process overall.

Check out: https://www.ws2coating.com/blog/a-co...num-disulfide/

That is next level. Thank you. I am book marking that one.
 
I treat new no different than fired brass. Partial FL.
 
I didn't know they make the sizing mandrels. I had always thought there had to be a better way than to pull the sizing button out of the brass on the upstroke. I think I'll try a mandrel and see if that makes a difference for me.
 
Get the carbide neck turning mandrel from Sinclair, .002/.0025 tension. Needs very little lube,,otherwise they all will gall the inside of the neck. Lapua brass is extremely dry new
 
Get the carbide neck turning mandrel from Sinclair, .002/.0025 tension. Needs very little lube,,otherwise they all will gall the inside of the neck. Lapua brass is extremely dry new


+1, do not get the stainless mandrel, carbide only, this is the way to go.