Expanding mandrel

Sasquatch

Sasquatch

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I've got too much time on my hands and have been watching youtube loading videos, and I keep coming across expanding mandrels instead of expander balls to get more consistent neck tension. What I'm really confused about is one of the newer ones says this:

The NEW Wilson Expanding Mandrel Sizing Die. This die is designed to be used on NEW brass cases
Click to expand...

What happens after I fire it? A different mandrel? When I do a full-length (or bump) size, it compresses the case neck. The expander ball stretches the case and neck. It is smaller than I want (what I keep hearing is 2 or 3 thou smaller than bullet diameter).
 
Sasquatch said:
I've got too much time on my hands and have been watching youtube loading videos, and I keep coming across expanding mandrels instead of expander balls to get more consistent neck tension. What I'm really confused about is one of the newer ones says this:



What happens after I fire it? A different mandrel? When I do a full-length (or bump) size, it compresses the case neck. The expander ball stretches the case and neck. It is smaller than I want (what I keep hearing is 2 or 3 thou smaller than bullet diameter).
Click to expand...

You want to run expander mandrels when not running the expander ball in your sizing die. The expander ball tends to induce runout in the cartridge neck in some instances.

The theory is that the downward force on the case from an expander mandrel is superior to the upward force from an expander ball.

A sizing die without the expander ball will undersize the case neck. So you would use an expander mandrel to upsize the neck to the desired tension.

Typically people shoot for .002-.003 neck tension.
 
I use Redding and other bushing dies with no expander ball. Fired cases have larger than optimal case necks. In some "cases", the neck will so large that a bullet will literally fall in the neck. I typically only use a mandrel on new brass where the case neck is typically too tight to begin with. I also use an expanding mandrel to make 30BR cases from 6BR cases. K& M makes mandrels and the special die needed to perform the mandrel operation.
 
I use a Sinclair mandrel for all new brass. It makes all the necks consistent to start with. Then I use Redding bushing dies for sizing calibers that I shoot for accuracy. I generally try for -.002 tension on bolt gun rounds and -.003 to -.004 for gas gun brass. I don't crimp.

I also use one for all range pickup brass. For plinking ammo I'll run them through a regular sizing die with a carbide button. Dipping the necks in graphite powder really helps mitigate the drag from the button.
 
jimmyjames8 said:
I use Redding and other bushing dies with no expander ball. Fired cases have larger than optimal case necks. In some "cases", the neck will so large that a bullet will literally fall in the neck. I typically only use a mandrel on new brass where the case neck is typically too tight to begin with. I also use an expanding mandrel to make 30BR cases from 6BR cases. K& M makes mandrels and the special die needed to perform the mandrel operation.
Click to expand...

That's one of the things I'm trying to figure out- using the outside diameter as with a bushing is brass-thickness dependent. Meanwhile a mandrel is only the inside diameter and relates to the size of projectile?
 
REELDOC said:
I use a Sinclair mandrel for all new brass. It makes all the necks consistent to start with. Then I use Redding bushing dies for sizing calibers that I shoot for accuracy. I generally try for -.002 tension on bolt gun rounds and -.003 to -.004 for gas gun brass. I don't crimp.

I also use one for all range pickup brass. For plinking ammo I'll run them through a regular sizing die with a carbide button. Dipping the necks in graphite powder really helps mitigate the drag from the button.
Click to expand...
To get consistent tension, that means you have to change bushings for different kinds of brass?

I'm intruiged about the graphite use- is that the 'birdshot with dry lube' that I've seen in some videos, or do you just put some on a q-tip?
 
Yes on both your above questions. My benchrest brass is always Lapua so brass thickness is consistent. Reloaders that use bushings will have a collection. Ive gone back to a Lee FL resizer for 308. I shot a best ever 1 hole group with new FC 308 brass that I ran thru that cheap Lee. It has a built in mandrel that is the decapping rod.
 
Sasquatch said:
That's one of the things I'm trying to figure out- using the outside diameter as with a bushing is brass-thickness dependent. Meanwhile a mandrel is only the inside diameter and relates to the size of projectile?
Click to expand...
I always buy a minimum of 200 and generally 400 pieces of new brass for all the accuracy guns/calibers I have. I take a piece of that brass and size it down pretty tight with the bushing die. I then load a boolit and measure the loaded neck thickness, Take the neck thickness, subtract the amount of tension I want and choose a bushing that will provide that tension. I take another piece of brass, size it with that bushing to make sure it is the right one. I do all of that brass at one time and put it away to be used later. I put the 1st piece of loaded brass in a zip lock bag with the info I used to get it to the loaded state. With that I put the sized only piece in the bag with a note on the bushing size. I probably have at least 5 or 6 different size bushings for each caliber.

Your fired brass may require a different bushing since the neck will expand when fired. You will probably have to start with a couple thou larger and work from there.

Now a caveat to this is that new brass generally does better after it has been fired once. Benchrest shooters like Jimmy and that type of shooter may take 50 or a 100 pieces of the brass, fire form them and keep loading that 50 until they go south. Then they'll do the next 50. Most of them will neck size that brass if they have a custom reamed chamber that is damn near perfect. I always full length size.

This is the powder I use. Heck, a little cup full lasts forever. Do not spill the cup.............it is really ugly to get up.šŸ˜«

REDDING IMPERIAL DRY NECK LUBE- 1 OZ. | Brownells

This graphite based powdered neck lube will reduce the chatter and drag on your cases in the sizing die. The dry powdered ...
www.sinclairintl.com

Correct anything you read here Jimmy. I haven't shot benchrest or F-Class in a long time and things might have changed.
 
Iā€™ve gone way overkill on some of my brass.

I turn the necks for consistent thickness around the circumference. That made a significant difference in my extreme spread when I checked. I like to use a bushing die, but I use a bushing that will undersize by by maybe .001ā€, then use a mandrel expander. This will allow for a very slight variation in wall thickness.
 
There is a issue of Handloader Magazine at some grocery stores now, detailed article on turning and sorting brass to neck thickness (+/- 0.001") with group sizes before and after the turning and sorting. Pretty amazing results. All my BR brass is neck turned. Bryan Litz, noted balistician, says in one of his first 2 books, that medium to high neck tension in 223 makes for lower ES. In 308 neck tension made no statistical difference. I'm sure others have done neck tension experiments on other calibers. I'm experimenting with my 30BR now.
 
REELDOC said:
I always buy a minimum of 200 and generally 400 pieces of new brass for all the accuracy guns/calibers I have. I take a piece of that brass and size it down pretty tight with the bushing die. I then load a boolit and measure the loaded neck thickness, Take the neck thickness, subtract the amount of tension I want and choose a bushing that will provide that tension. I take another piece of brass, size it with that bushing to make sure it is the right one. I do all of that brass at one time and put it away to be used later. I put the 1st piece of loaded brass in a zip lock bag with the info I used to get it to the loaded state. With that I put the sized only piece in the bag with a note on the bushing size. I probably have at least 5 or 6 different size bushings for each caliber.

Your fired brass may require a different bushing since the neck will expand when fired. You will probably have to start with a couple thou larger and work from there.

Now a caveat to this is that new brass generally does better after it has been fired once. Benchrest shooters like Jimmy and that type of shooter may take 50 or a 100 pieces of the brass, fire form them and keep loading that 50 until they go south. Then they'll do the next 50. Most of them will neck size that brass if they have a custom reamed chamber that is damn near perfect. I always full length size.

This is the powder I use. Heck, a little cup full lasts forever. Do not spill the cup.............it is really ugly to get up.šŸ˜«

REDDING IMPERIAL DRY NECK LUBE- 1 OZ. | Brownells

This graphite based powdered neck lube will reduce the chatter and drag on your cases in the sizing die. The dry powdered ...
www.sinclairintl.com

Correct anything you read here Jimmy. I haven't shot benchrest or F-Class in a long time and things might have changed.
Click to expand...
All sounds good. Everybody does things a little different. I keep adding steps to my brass prep but I have a bud who does litterally nothing other than FL resize his dirty brass, prime charge and seat and he shoots amazing groups.
 
jimmyjames8 said:
All sounds good. Everybody does things a little different. I keep adding steps to my brass prep but I have a bud who does litterally nothing other than FL resize his dirty brass, prime charge and seat and he shoots amazing groups.
Click to expand...
Me too Jimmy. My bud held a lot of titles with a 6ppc. First time I shot it he pulled out a zip lock bag of dirty primed brass, some powder and bullets. He dipped the brass in the powder, barely put the bullet in the mouth and laid it on the ramp. Then he real slow like seated the bullet when he closed the bolt. I'm sitting there going WTF. He said shoot it so I hunkered down on it and barely brushed the trigger and pew. Turns out it has a roughly 2oz trigger and all you have to do is touch the trigger from outside of the trigger guard.

I'm still anal about it but I only have one 22-250 that I turn the necks on.
 
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