Which case neck expander mandrel

DCG

Well-Known Member
Rather than neck sizing, using a collet or full length die, to set the diameter of the outside of the neck, during case preparation. I’m going to have a go at sizing the inside of the neck, using an expanding mandrel and holder, to set the neck tension, which seems an awful lot more logical to me, from a consistency point of view.
In the past I’ve used a K&M expander body and mandrel, to expand the case neck prior to neck turning. However I found there wasn’t an awful lot of space between the mandrel and shell holder to actually get the case into and out of the the press even with the die set at its highest, it almost seemed like my press was to short, or the die was set down to low in the press.
I’d be grateful to hear from anyone else thats had this problem with the K&M adapter and or any recommendations of another brand or design, which you’ve had success with.
Regards to all.
dcg
 
Watching with interest as your problem stems (no pun intended) from the threaded stem that enters the case and acts as the stop that determines ram travel.

K
 
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Hi JCS,
Any particular reason why the Sinclair body, but using Twenty First Century mandrels? Or if you were buying now, would you just use the 21st century body etc etc ?
dcg
I started out with Sinclairs kit, I only recently bought the Twenty First Century mandrels.
Regards
JCS
 
I use a 21st Century body and mandrels, ordered from .222 and went up in half thou increments to .224

Have settled at 1 thou neck tension and tested 1.5 thou but found very little difference in accuracy. May dabble with it again after lockdown.
 
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I use a 21st Century body and mandrels, ordered from .222 and went up in half thou increments to .224

Have settled at 1 thou neck tension and tested 1.5 thou but found very little difference in accuracy. May dabble with it again after lockdown.
Hi DVS1,
Which caliber was that for. I’m currently reloading for 7mm-08 and 22-250, I was proposing to try .002“ of tension, to start with, on both calibers.
dcg
 
I still use K@M , i agree some press bodys are so thick the unit seems to be very short when screwed down ,but a long/tall shell holder on the that stage is how i got over it still looks odd but works as needed.
 
Just as another option, have a look at the APW expander mandrel set. Comes as a set for multiple calibre’s, with mandrels for 1 and 2 thou neck tensions in each calibre. Reasonable prices and the quality is very good indeed. I bought a set recently and although I’ve not had much chance to test properly since I got it, I’m happy with the results so far.
 
Thats with .223 mate, you can order direct from 21st century and I did a job lot to ensure I had the right size from the off
Had a look on the 21st century website and it took a bit of a wobbler with shipping to the U.K. when I tried to place an order.
 
Had a look on the 21st century website and it took a bit of a wobbler with shipping to the U.K. when I tried to place an order.
Strange that...mind you I ordered mine pre Brexit not that that should affect things, straight through and they even marked the paperwork at $10 happy days lol
 
Ordered the 21st century expander and mandrels, the website was taking umbridge at me putting UK as country, had to put U.K. in before it would recognise it.
Thanks for all of your help guys.
dcg
 
Used to use sinclair when I completed like them al, you buy Mandrel separate and the body holds all
Now in my 260 I use LE Wilson and only use it to expand and true new brass or size up 243 cases
Definitely 100% decreases run out created my external neck sizing but you have to start with new brass
 
Rather than neck sizing, using a collet or full length die, to set the diameter of the outside of the neck, during case preparation. I’m going to have a go at sizing the inside of the neck, using an expanding mandrel and holder, to set the neck tension, which seems an awful lot more logical to me, from a consistency point of view.
In the past I’ve used a K&M expander body and mandrel, to expand the case neck prior to neck turning. However I found there wasn’t an awful lot of space between the mandrel and shell holder to actually get the case into and out of the the press even with the die set at its highest, it almost seemed like my press was to short, or the die was set down to low in the press.
I’d be grateful to hear from anyone else thats had this problem with the K&M adapter and or any recommendations of another brand or design, which you’ve had success with.
Regards to all.
dcg
Interesting I use lee collet neck sizer. This forces the neck onto a mandril and produces low run out accurate neck sizing. I have a couple of different mandrills if I want different neck tension .
 
Watching with interest as your problem stems (no pun intended) from the threaded stem that enters the case and acts as the stop that determines ram travel.

K
I’ve simply removed the threaded stem. J can see the case on the mandrel via the window adaptor which prevents me from going too far, so need for the ‘stop’.
 
Interesting I use lee collet neck sizer. This forces the neck onto a mandril and produces low run out accurate neck sizing. I have a couple of different mandrills if I want different neck tension .
I too use the Lee collet die, which I find to be good.

However I am experimenting with precise shoulder bumping every time, first using the FL die. Followed by a trip through the collet one, to true up any irregularities. The Lee collet mandrel is also unique in that it locates in the flash hole so aligns down the full length of the case. I also feel that a partial FL resize every time is the best way to consistency, same internal case volume every time.

The mandrels are inexpensive, quickly interchangeable, available in a variety of sizes, or I think Lee can even make you a "special", but they can simply be sanded down to a smaller size.

So far so good, but I make no claims as to improved accuracy yet. Even considering removing the expander rod from the FL die and letting the mandrel in the collet die do the work, but not tried that yet. Since I already had both dies I thought it might be an interesting experiment.
 
I have no experience with expander mandrels.
Is it necessary or advisable to apply some (dry) lube when using them?
 
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