Expander mandrel roughed up

[lukester]

Is it just inevitable that an expander mandrel is going to get "scratched up" or actually covered w/ brass streaks/buildup as its used? Mine is a 21st Century caliber-specific and I'm using it on untumbled virgin Lapua brass.

At first, I thought it was because I was chamfering/deburring the brass before running it through the bushing sizer and then the expander die (again - new brass, so no trimming yet). But realizing I needed to ultimately switch that order, I've only sized & expanded this brand new batch of brass so far, and I'm just unsure because of how "rough" the expander mandrel is afterwards. (And it was silky smooth to start with.) I know all of that "roughness" has to also be present now on the inside of the necks, too, right?

Or does virgin brass need to be chamfered/deburred before the expanding step to cut down on the rough edges that lead to build-up on the mandrel?... (Although it didn't "feel" any different working the Forster Co-ax up and down w/ the expander die this go-round... i.e. the feel of expanding right-out-of-the-box brass vs. new brass that has been chamfered/deburred.)

All of that being said, this combo of sizing, expanding the virgin Lapua 284 Win, etc. is working very well for me. After a long process of load development & testing, I shot my first-ever competition 2 weeks ago (a 3x600) and shot 199-12x, 199-11x, and 199-8x. So I definitely can't complain about the results, but I just wondering about all the small details that can eventually add up.

Thanks,
Luke

 

[memilanuk]

Repeat after me:

"Lube the inside of the necks"

Bare metal against bare metal results eventually in some level of galling.

Virgin brass is particularly susceptible, as that stuff is squeaky clean inside.

 

[1shot]

I use powdered graphite applied with a woman's eyelash brush. Never had a galling problem using this method.

Lloyd

 

[rijndael]

Or does virgin brass need to be chamfered/deburred before the expanding step to cut down on the rough edges that lead to build-up on the mandrel?...

I chamfer and debur before doing any sizing or mandrel operations.

 

[coorslight]

I use the powdered graphite with the same result as Lukester.

 

[KMart]

Or does virgin brass need to be chamfered/deburred before the expanding step to cut down on the rough edges that lead to build-up on the mandrel?... (Although it didn't "feel" any different working the Forster Co-ax up and down w/ the expander die this go-round... i.e. the feel of expanding right-out-of-the-box brass vs. new brass that has been chamfered/deburred.)

New virgin Lapua brass needs to be tumbled in walnut media for about 3 hours before you do any case prep on it. That gets the oxidation off the inside and outside of the case neck that is left from the final annealing step from the factory. Doing this step first will prevent scratched up necks and build up on your reloading tools, dies, mandrels etc.

 

[rijndael]

New virgin Lapua brass needs to be tumbled

FWIW: It makes a big difference for just-annealed brass too.

 

[fkimble@charter.net]

Why are you sizing new brass? Will it not fit in your chamber? Just lube the inside of neck or the mandrel and run it in to cleanup any deformed from shipping neck and reduce neck tension for first shot.

Frank

 

[Webster]

Is it just inevitable that an expander mandrel is going to get "scratched up" or actually covered w/ brass streaks/buildup as its used? Mine is a 21st Century caliber-specific and I'm using it on untumbled virgin Lapua brass.

At first, I thought it was because I was chamfering/deburring the brass before running it through the bushing sizer and then the expander die (again - new brass, so no trimming yet). But realizing I needed to ultimately switch that order, I've only sized & expanded this brand new batch of brass so far, and I'm just unsure because of how "rough" the expander mandrel is afterwards. (And it was silky smooth to start with.) I know all of that "roughness" has to also be present now on the inside of the necks, too, right?

Or does virgin brass need to be chamfered/deburred before the expanding step to cut down on the rough edges that lead to build-up on the mandrel?... (Although it didn't "feel" any different working the Forster Co-ax up and down w/ the expander die this go-round... i.e. the feel of expanding right-out-of-the-box brass vs. new brass that has been chamfered/deburred.)

All of that being said, this combo of sizing, expanding the virgin Lapua 284 Win, etc. is working very well for me. After a long process of load development & testing, I shot my first-ever competition 2 weeks ago (a 3x600) and shot 199-12x, 199-11x, and 199-8x. So I definitely can't complain about the results, but I just wondering about all the small details that can eventually add up.

Thanks,
Luke

Quit using the expander many years ago. I chamfer new brass before sizing to remove any little nibs sticking proud. These tiny nibs are what break off and stick to the dies, the mandrel and scratch the brass. Also give a very light twist of chamfering before each reload. Two GH hunting rifles both shoot groups under 0.400". I use bushing dies no lube inside the neck. If your using an expander I would definitly lube the case neck i.d. I lube my cases with a light vis petroleum oil. Pet oil has been the best lube for machinery for over 100 years. I worked 18 years in research for an oil company.

 

[lukester]

Thanks so much - everyone - for the input. The recent batch might have been the last batch of new brass that I process for this particular rifle for a while as I'll now probably cycle back around w/ the several hundred once-fired cases... but I also have a new build in process and wanted to get this figured out for that reason and just general knowledge sake.

It makes sense that minor factory imperfections could be dealt with by tumbling first. I can also see the reasoning for lube on the mandrel and/or dry graphite inside the necks... although I guess that does create the need for another tumble session afterward to remove, right?

I definitely will take your suggestions and see if I can get this resolved/behind me. For f-class, I know that every little variable that can be somewhat controlled (brass prep, charge, seating depth, etc, etc, etc,) can have an effect. All of that so that I can point the finger only at the mirror for those 9's or worse/blown wind calls

How about this recent batch of 200 pieces? Any consensus on whether I should just load them (after chamfering/deburring, of course) or do I need to somehow polish up the inside of the necks first to improve their consistency. Again, the batch before this certainly shot very well, but is it possible that "one" piece w/ extra galling from last time was the piece that helped me drop a 9 on shot 16 of my last relay and keep me from my first clean? (Actually, I know it was me and could afterward see a trend toward the lower section of the 10-ring that I missed on the shotmarker leading up to that one... but a guy still wonders, right?)

Thanks,
Luke

 

[KMart]

FWIW: It makes a big difference for just-annealed brass too.

Annealing puts oxidation back on the brass to some extent but not as bad as the new stuff. I have seen the same thing.

 

[Pawnee Bill]

Take some 600 or 1000 grit wet/dry sandpaper and polish your mandrel. Easy fix.

 

[memilanuk]

New virgin Lapua brass needs to be tumbled in walnut media for about 3 hours before you do any case prep on it. That gets the oxidation off the inside and outside of the case neck that is left from the final annealing step from the factory. Doing this step first will prevent scratched up necks and build up on your reloading tools, dies, mandrels etc.

At some point *after* fighting this problem for a while, I saw a recommendation - supposedly from a Lapua rep at the time - to tumble virgin brass in some old, dirty media. Partly to address the oxidation, but also because the residual dust left behind helped a little as a sort of dry lube.

Either way, it does make a noticeable difference. Maybe not as much as actual neck lube, but a whole lot less messy and annoying to do.

As for removing the build up on the mandrel... #0000 steel wool was my go-to.

 

[lukester]

Thanks PB and Milanuk... I think I'll definitely be a tumbler w/ new brass from now on. And the mandrel definitely polishes back up easily enough.
How about the brass that's already been processed, though. That buildup on the mandrel came from the inside of the necks, so I assumed they were now scratched up. Just checked, and sure enough - the vertical lines are definitely visible. Should I try and spin some super fine steel wool inside there to clean them up?...

 

[memilanuk]

My observation has been that those lines are less from any galling that may have occurred, and more of an artifact from sizing the neck. Shoot 'em and size' em a couple times and don't worry about it.

 

[dgeesaman]

Thanks PB and Milanuk... I think I'll definitely be a tumbler w/ new brass from now on. And the mandrel definitely polishes back up easily enough.
How about the brass that's already been processed, though. That buildup on the mandrel came from the inside of the necks, so I assumed they were now scratched up. Just checked, and sure enough - the vertical lines are definitely visible. Should I try and spin some super fine steel wool inside there to clean them up?...

As long as your seating force is smooth and consistent, I wouldn’t worry about it.

I have had brass that got very grabby when I seated some bullets - that’s not a good sign for accuracy.

David