Setting neck tension with expander mandrel and bushing die questions

Blaster01

Well-Known Member
Joined
Jan 26, 2020
Messages
216
Location
Salem
So this is my first time using the expander mandrel. I just got in the mail a whidden gunworks click adjustable full length bushing die for my 300 prc. I ordered the Sinclair expander die and the 30 cal carbide mandrel before the sizing die. To my understanding, people are just taking the expander ball out of their Redding or similar bushing dies, sizing the case and neck with the bushing, and then running the brass through the expander die to expand it. My first question is, do the whidden dies have an expander mandrel or do they come with the ball, to me it looks like a mandrel and I can post a picture of what I got if you guys want. My second question is, can you guys explain your process when setting neck tension with a bushing die and expander mandrel? Without turning necks. From my understanding a guy would select the correct bushing after measuring the neck of a case with a bullet seated in it, size the case with said bushing, and then run it through the expander die with the mandrel. Am I missing something or just overthinking it?
 

Blaster01

Well-Known Member
Joined
Jan 26, 2020
Messages
216
Location
Salem
Correct, you dont want to use the expander ball in your sizing die.

If you're using a bushing sizing die, size .002-.003 under then use your expander mandrel to take the neck to .001 under bullet diameter.
So I measured a seated 225 eldm at .338. I ran everything through the bushing die with a .336 bushing. For 2 thousandths tension. When I run them over the expander mandrel next, that won’t change my 2 thousands neck tension? Another thing I have to add is that on the new brass, the necks were only .3345 outside diameter. Which means they didn’t get sized with the bushing at all because they are already smaller, I only sized with the bushing incase a few of the necks were bigger than the majority. So this means on the new brass I will have 3.5 thousandths neck tension until it shoot it and resize the once fired with that bushing. Correct? I know, a lot of questions. I hope my thinking is making sense. Sometimes I can get a little ahead of myself when trying to put my thoughts into words lol especially since I’m new to all this. Thanks for your time!
 

Slick8

Well-Known Member
LRH Team Member
Joined
Aug 13, 2012
Messages
668
Location
The Republic of Texas
Yeah new brass would have needed to be sized regardless.

Just run it ththrough the mandrel which will give you .001 under cal.

If using a mandrel it really doesn't matter if you use a bushing or standard die as it will under size it then you'll set final tension with the mandrel.

To get the best results, you're to want to anneal otherwise you'll eventually work harden the brass which will cause spring back on your neck dimension.
 

antelopedundee

Well-Known Member
Joined
Oct 14, 2018
Messages
1,132
Location
Iowa
I don't use the bushing die approach, but it seems to this observer that if one used the proper size bushing that that would obviate the need for an expander mandrel. Of course that would be better if your cases had uniform wall thickness in the neck.
 

L.Sherm

Well-Known Member
LRH Team Member
Joined
Jul 26, 2017
Messages
3,853
If you only run a .307 mandrel you will only end up with about. 0015 neck tension with springback which is not much especially for a 30 cal.
 

L.Sherm

Well-Known Member
LRH Team Member
Joined
Jul 26, 2017
Messages
3,853
I've got alot of Whiddens dies, try out his expander ball there pretty slick I get very little runout with them. I am messing with mandrels but I'm not getting any better runout than with John's expander mandrels which is at the very most .001 most are .0005
 

antelopedundee

Well-Known Member
Joined
Oct 14, 2018
Messages
1,132
Location
Iowa
If you only run a .307 mandrel you will only end up with about. 0015 neck tension with springback which is not much especially for a 30 cal.


The problem with the Sinclairs IMO is that they don't offer enough variety in expander mandrels. For .264 there is .263 and .262. I'd prefer to have a .261.
 

brguide

Well-Known Member
Joined
Oct 13, 2013
Messages
106
Location
Globe, AZ
You can get on whiddens website and order a kit of expanding mandrels for your whidden die. That what I did so that way you can fine tune. Get some more bushings and mandrels and try different combinations to see what works best for your cartridge. That way if you ever change brass to another brand you have everything you need to change out. Love whidden dies and especially the click die.
 

Primary

LRH Assistant
Here are some related products that LRH members are talking about. Clicking on a product will take you to LRH’s partner, Primary, where you can find links to LRH discussions about these products.

 
 
Top