Expander mandrel scoring

[Slim13]

Long time reader, first time posting. I'm new to reloading. Having said that, I bought some lapua brass (260) and setup an expander mandrel (Sinclair) to open up the tight necks. I thought there were numerous ways to lube the neck prior to running the mandrel through them. I elected to go with imperial dry lube because it seemed less messy, and I figured the liquid lube would be better served on FL sizing. I ran 40 pcs of brass through the expander mandrel and it seemed smooth. ID of case necks are uniform, but towards the end I noticed some scoring on the inside of the necks. I disassembled the die and saw some brass transfer on the mandrel. Am I missing something here?

 

[XBBR Shooter]

Long time reader, first time posting. I'm new to reloading. Having said that, I bought some lapua brass (260) and setup an expander mandrel (Sinclair) to open up the tight necks. I thought there were numerous ways to lube the neck prior to running the mandrel through them. I elected to go with imperial dry lube because it seemed less messy, and I figured the liquid lube would be better served on FL sizing. I ran 40 pcs of brass through the expander mandrel and it seemed smooth. ID of case necks are uniform, but towards the end I noticed some scoring on the inside of the necks. I disassembled the die and saw some brass transfer on the mandrel. Am I missing something here?

The brass started to stick to the Sinclair mandrill and it was that build up that scored the inside of the necks - clean it off with bore cleaner and then use s water soluble lube like RCBS Lube-II, and then wash the cases when you are done.

 

[Slim13]

The brass started to stick to the Sinclair mandrill and it was that build up that scored the inside of the necks - clean it off with bore cleaner and then use s water soluble lube like RCBS Lube-II, and then wash the cases when you are done.

Thanks. Should I run them through the mandrel again to smooth the scoring? And by washing are you saying to put them in a tumbler?

 

[Ned Ludd]

I use a very liberal application of Hornady One-Shot lube prior to the expander mandrel and subsequent FL resize. I have not had issues with buildup of brass on the mandrels; however, I give them a quick polish fairly regularly with super fine steel wool. Not enough to do much other than polish them up. After the expander mandrel, I can see longitudinal lines on the inside of the case neck, but they're basically only in the oxidation layer that might be a few molecules thick at best. They're not deep scratches into the brass. I have not had any issues with regard to precision because of these faint marks that I am aware of.

 

[XBBR Shooter]

Thanks. Should I run them through the mandrel again to smooth the scoring? And by washing are you saying to put them in a tumbler?

The mandrill will not smooth the scores - nothing will, but they are cosmetic, so don't lose sleep over it.
When I say wash, I mean wash the cases in hot water and let them dry, or dry them in the oven @ 200 degrees.

 

[Slim13]

I appreciate the help as a travel down this rabbit hole of reloading!

 

[rardoin]

I use a slight smear of lanolin on the case mouth prior to expanding. No issues with galling of the brass onto the mandrel. IIRC, Hornady Unique is also lanolin based. Lanolin was used for many years as a die lube when drawing brass wire, a process in which galling would be disastrous for the product.

 

[jlow]

Long time reader, first time posting. I'm new to reloading. Having said that, I bought some lapua brass (260) and setup an expander mandrel (Sinclair) to open up the tight necks. I thought there were numerous ways to lube the neck prior to running the mandrel through them. I elected to go with imperial dry lube because it seemed less messy, and I figured the liquid lube would be better served on FL sizing. I ran 40 pcs of brass through the expander mandrel and it seemed smooth. ID of case necks are uniform, but towards the end I noticed some scoring on the inside of the necks. I disassembled the die and saw some brass transfer on the mandrel. Am I missing something here?

Yes, you should have use the Imperial sizing lube on the inside of the case neck. If you do this, you will not have any galling on the mandrel or scoring of the case neck. The dry lube just does not work as well because not enough of it sticks to the neck/mandrel, which ever one you tried applying it to.

 

[mikecr]

Lube is only needed for expansion of squeaky clean(new necks). After firing, the carbon layer is all the lube ever needed.

 

[zipollini]

Deprime
Anneal
SS tumble
Dry
Spray outside of case and inside of neck with One Shot spray lube
FL size with Redding type "S" sizing die with neck bushing
Expand neck with Sinclair Gen II expander mandrel
Trim, and chamfer inside and outside of neck with Giraud trimmer
Re uniform primer pockets

Spin a bronze brush that has been covered with 0000 steel wool inside of necks to polish neck and smooth out chamfer

Rinse off One Shot lube with 90% isopropyl alcohol and run nylon brush up and down inside of neck

dry

Works for me. No neck scratching or galling at all. Neck IDs are smooth as silk and I don't need any further lube to seat bullets.

 

[LHSmith]

Three applications in precision reloading where the use of carbide tooling has no equal : 1/ expander mandrels, neck turning cutter mandrels, and 3/ neck sizing bushings. Buy once and eliminate potential problems in the future.

 

[MrMajestic]

Try chucking the mandrel in a drill and polish it with JB or Iosso on a rag. It will not make a measurable, at least without some high tech equipment/environment, and the polished surface will not collect brass from the necks. JMHO/works for me

 

[rardoin]

Lube is only needed for expansion of squeaky clean(new necks). After firing, the carbon layer is all the lube ever needed.

I should have clarified my prior post....I use lanolin only on new cases/cases during forming process. On fired cases I use the Imperial dry lube if I have pin tumbled the cases. I have not had galling with the dry lube or residual carbon in fired cases. I use a K&M expander.

 

[Shynloco]

The brass started to stick to the Sinclair mandrill and it was that build up that scored the inside of the necks - clean it off with bore cleaner and then use s water soluble lube like RCBS Lube-II, and then wash the cases when you are done.

+1. Having been where you are using a mandrel die as well as other times using a Small based die, I found that RCBS Lube II to be the most efficient lubricant for those purposes. Now I use Imperial Resizing was when FL Resizing, but that Lube II works better for the aforementioned purposes. And don't be shy in the amount you use as you'dd be cleaning and washing the brass anyways. Worked for me and no brass sticking or shaving caused by a dry mandrel.

Alex

 

[mikecr]

I mandrel pre-expand(pre-seat) necks just prior to every case charging, so I don't desire another cleaning operation between.
While I also love RCBS case lube for sizing, for my mandrels I've dry lubed them with WS2(tungsten disulfide), for new necks.
WS2 is similar in properties to carbon(fouling-wise) but slippery as all get out.

Eventually I'll replace all my mandrels with harder versions ($$$)..

 

[Slim13]

The mandrill will not smooth the scores - nothing will, but they are cosmetic, so don't lose sleep over it.
When I say wash, I mean wash the cases in hot water and let them dry, or dry them in the oven @ 200 degrees.

Attached is a picture of the inside of the case necks. The grooves look and feel pretty deep. Do these look like they'll be ok to use still?
Thanks

 

[nmkid]

I don't think washing will help! I hope the scoring isn't as bad as the pictures portray.

 

[Brians356]

Lube is only needed for expansion of squeaky clean(new necks). After firing, the carbon layer is all the lube ever needed.

Another reason not to clean cases squeaky clean.

FWIW I have noticed the finish on expander mandrels can vary, from shiny smooth to "frosted" or matte. The latter would tend to pick up brass, it seems to me. But it may be that with proper lube the matte finish is actually better. Makes me wonder.
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[jlow]

View attachment 986564

Attached is a picture of the inside of the case necks. The grooves look and feel pretty deep. Do these look like they'll be ok to use still?
Thanks

Slim13 - a couple of things. One is apart from using Imperial lube on the necks before sizing with the mandrel, it is also worthwhile to polish the mandrel with a fine metal polish so that it is almost mirror like.

In terms of how rough your necks feel inside, just chuck up an old nylon brush and wrap it with 0000 steel wool and spin it in the neck with the brush chucked up in a drill, it will smooth out quickly. This is not a minute ling operation, just 5 seconds will do it. Make sure you clean the inside of the case with a vacuum because the steel wool will shed inside.

 

[Brians356]

Attached is a picture of the inside of the case necks. The grooves look and feel pretty deep.

Were those brand new unfired cases?

Since new case mouths will be irregular and out of round (on regular bulk brass), you might try partially expanding them first, just enough to round out the mouths sufficient to then chamfer the inside of the mouths, minimally, using a Wilson or similar tool. Then spin the mouths against some 0000 steel wool, to smooth them out. Now when you expand them in earnest, there will less chance of galling, and the mandrel will run in much more smoothly.
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