Expander Mandrel Help

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marshall18X20 MONTHS
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Expander Mandrel Help
11/28/2016

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It's sounds like I can improve my set up on my hornady dies by removing my expander ball and using and expander die with a mandrel instead.

I need some help with which mandrel to buy. I was looking at the Sinclair die but need help selecting the mandrel. From the description is sounds like this turning mandrel is the correct one to buy for my bolt action rifle.

http://www.sinclairintl.com/reloadi.../sinclair-neck-turning-mandrel-prod33136.aspx

is this the correct mandrel to use for my application? My goal is to help with consistent neck tension. Am I headed in the correct direction?

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nexusfireXFirst Sergeant
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Re: Expander Mandrel Help
11/28/2016

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Yes that is correct. I would get the carbide one if you can. Expander should be .002 smaller that your bullet.

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marshall18X20 MONTHS
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Re: Expander Mandrel Help
11/28/2016

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nexusfire wrote:

Yes that is correct. I would get the carbide one if you can. Expander should be .002 smaller that your bullet.​

What is the benefit of the carbide mandrel. No lube needed?

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nexusfireXFirst Sergeant
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Re: Expander Mandrel Help
11/28/2016

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Yes and easier on the brass

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sdintowaXPrivate
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Re: Expander Mandrel Help
11/29/2016

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Is it best to neck size with a bushing before or after the mandrel?
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MtCreekXFirst Sergeant
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Re: Expander Mandrel Help
11/29/2016

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If you're using a mandrel, that should be the last thing you do to the neck.

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sdintowaXPrivate
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Re: Expander Mandrel Help
11/29/2016

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Got it, so normal sizing practices and end with mandrel. Thanks!!
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Killshot44XGunny Sergeant
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Re: Expander Mandrel Help
11/30/2016

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sdintowa wrote: Got it, so normal sizing practices and end with mandrel. Thanks!!​

If you're using a bushing die (neck or full length) THAT is what should set the neck tension. If you're concerned about non-concentric case mouths I would use an oversized expander mandrel die (as used before neck turning) to open the mouth and even out any problems and then final size with a bushing die.

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sdintowaXPrivate
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Re: Expander Mandrel Help
11/30/2016

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Thanks! So I noticed the small inside doughnut in my case mouth, wanted to use the mandrel to take care of that and straighten everything else. So with the mandrel, one can stop using any bushing dies or do you sometimes need to go back and forth?
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SheldonN

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Re: Expander Mandrel Help
11/30/2016 Last edited 11/30/2016 by SheldonN

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I think that's backwards. Most shooters I've heard use the mandrel as the final step in brass prep after running the case neck through the full length sizing/bushing die. This includes top level F-Class and PRS shooters using a mandrel as part of their brass prep who have written informative articles on the subject.

The concept is that you want the ID of the neck to be the most consistent/concentric portion. If there are variations in the thickness of your neck (and there almost certainly are unless you're neck turning), using a mandrel will push those variations to the outer diameter and leave the inside perfectly round. That's going to help both with concentricity and neck tension.

You still need to use a bushing die to size the neck just slightly smaller than the mandrel size, so that the mandrel does a little bit of work. For example if you're using a mandrel that's 0.002" under bullet diameter then you'd want a bushing that sized the case to 0.003" under so the mandrel only had to open up the case mouth 0.001. This minimizes your brass working. An alternative to a bushing die is having a normal full length die custom ground to give 0.003" under, but you'll need measurements of your brass thickness in order to do that since you can't just swap out a bushing like with a bushing die. The custom ground die will likely give better concentricity though.

I get using a mandrel to take out a case mouth dent prior to sizing, but you wouldn't want a mandrel that was even more oversized than your chamber (which is already probably a few thou larger than bullet diameter, and already concentric). That wouldn't make sense at all.

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blueorionXSergeant
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Re: Expander Mandrel Help
11/30/2016

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Sheldon is right on, cept you don't need to only use this techique with a bushing die. any die will work. I do this with both bushing and one piece dies. altho I like to have the one piece die's neck honed to 3 or 4 under bullet size.
FWIW
blueorion

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fursniper

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Re: Expander Mandrel Help
11/30/2016

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What Sheldon said, he's got the mandrel methodology wired. Exactly right.

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bigedp51XGunny Sergeant
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Re: Expander Mandrel Help
11/30/2016 Last edited 11/30/2016 by bigedp51

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A expander die like the Sinclair normally has two diameter mandrels, the standard mandrel is .002 smaller than bullet diameter and the neck turning mandrel is .003 smaller than bullet diameter.



The .003 less than bullet diameter neck turning mandrel is the bullet grip I use for my AR15 ammo and not crimp, and a normal expander is around .001 to .002 smaller than bullet diameter. And the link you posted is the smaller of the two mandrels and used for neck turning and far more bullet grip needed for a bolt action.



Expander Mandrels and Neck Tension

http://www.accurateshooter.com/technical-articles/reloading/expander-mandrels-and-neck-tension/



For simplicity I prefer using the Forster full length benchrest die with the high mounted floating expander that greatly reduces neck runout. With this die the neck of the case is held and centered in the neck of the die when the expander enters the case neck.



And at the Whidden custom die website they tell you that a non-bushing full length die produces the most concentric cases. And they also sell expander kits with five expanders in .001 increments




And the most common use for the Sinclair expander die is to expand the neck on new brass and then fire form the case. I use my Sinclair expander die mostly for neck turning and use full length Forster dies for almost everything else. On milsurp rifles with long fat chambers I neck size only and not over work the brass.

 

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SheldonN

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Re: Expander Mandrel Help
11/30/2016

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bigedp51 wrote:
A expander die like the Sinclair normally has two diameter mandrels, the standard mandrel is .002 smaller than bullet diameter and the neck turning mandrel is .003 smaller than bullet diameter.



The .003 less than bullet diameter neck turning mandrel is the bullet grip I use for my AR15 ammo and not crimp, and a normal expander is around .001 to .002 smaller than bullet diameter. And the link you posted is the smaller of the two mandrels and used for neck turning and far more bullet grip needed for a bolt action.​

Clarification, since Sinclair's own website is somewhat confusing on this. The normal mandrel (aka turning mandrel) will give you roughly 0.002" tension since it is sized 0.002 under bullet diameter. If you want a carbide mandrel this is the only size you can get from Sinclair. The oversized mandrel (aka expander mandrel) is 0.001 larger than the turning mandrel, so the brass can fit over the turning mandrel easier. The oversized mandrel being 0.001 larger means that you have LESS neck tension, so it will be roughly 0.001 under bullet diameter. Sinclair doesn't offer a mandrel that gives 0.003 tension, though I'm sure you could custom order one from somebody.



If you're going to use a mandrel to set neck tension for a bolt gun, I'd suggest the turning mandrel to get 0.002 tension. I'm fond of the carbide mandrel personally since it gives 0.002 tension and doesn't need lube like the regular steel mandrel.

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bigedp51XGunny Sergeant
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Re: Expander Mandrel Help
11/30/2016

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SheldonN wrote:

bigedp51 wrote:
A expander die like the Sinclair normally has two diameter mandrels, the standard mandrel is .002 smaller than bullet diameter and the neck turning mandrel is .003 smaller than bullet diameter.



The .003 less than bullet diameter neck turning mandrel is the bullet grip I use for my AR15 ammo and not crimp, and a normal expander is around .001 to .002 smaller than bullet diameter. And the link you posted is the smaller of the two mandrels and used for neck turning and far more bullet grip needed for a bolt action.​

Clarification, since Sinclair's own website is somewhat confusing on this. The normal mandrel (aka turning mandrel) will give you roughly 0.002" tension since it is sized 0.002 under bullet diameter. If you want a carbide mandrel this is the only size you can get from Sinclair. The oversized mandrel (aka expander mandrel) is 0.001 larger than the turning mandrel, so the brass can fit over the turning mandrel easier. The oversized mandrel being 0.001 larger means that you have LESS neck tension, so it will be roughly 0.001 under bullet diameter. Sinclair doesn't offer a mandrel that gives 0.003 tension, though I'm sure you could custom order one from somebody.



If you're going to use a mandrel to set neck tension for a bolt gun, I'd suggest the turning mandrel to get 0.002 tension. I'm fond of the carbide mandrel personally since it gives 0.002 tension and doesn't need lube like the regular steel mandrel.​

I cleaned my bifocals, broke out the magnifying glass and remeasured the mandrels and you are correct they are .001 and .002 smaller. And by the time I got back to my laptop the first time my short term memory loss kicked in, and this time I wrote it down.

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sdintowaXPrivate
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Re: Expander Mandrel Help
12/01/2016

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You guys rock!! Thanks,,pretty sure anyone who read this now knows all there is on using mandrel's.
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winniedonkeyXSergeant
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Re: Expander Mandrel Help
12/02/2016

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You can order a custom one here
http://kmshooting.com/custom-standard-expand-mandrels.html

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sdintowaXPrivate
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Re: Expander Mandrel Help
12/08/2016

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Ok, so hopefully this doesn't sound repetitive but still have questions.
Fired brass= neck expands and grows
Next, Deprime and neck size case to .002 smaller than caliber
(This is my question: when I now have to trim this case, my pilot is too large to fit being that I just sized it below the caliber size. Custom grid my pilots? Or another solution?)
After trim, run mandrel to set .001 neck tension(if using a non ground pilot on my trimmer, this mandrel won't really be doing anything at this point, again, unless my trimming pilot is a custom size)
Thoughts?
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bigedp51XGunny Sergeant
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Re: Expander Mandrel Help
12/08/2016

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The mandrels come in two sizes and one is for normal expanding of the neck and the other is .001 smaller for neck turning. Example the Sinclair expander die for my .223 has a .223 and .222 mandrel. And you use the smaller mandrel for neck turning. After brass spring back the case neck will fit tighter on the the turning mandrel and give better turning results.

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padom

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Re: Expander Mandrel Help
12/09/2016 Last edited 12/09/2016 by padom

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Trimming is another animal. If your shooting a bolt gun with a custom barrel and match chamber you shouldnt have to trim often. Depending on caliber, every 3-5 firings unless your shooting 6.5x47L then like NEVER!! Lol j/k.

You will have to measure your brass after each firing and trim when it is just about at or exceeds max length. When the time comes to trim, I would trim before neck sizing since you state you can't fit your brass into your trimmer after neck sizing.