Expander mandrel issues

[dellet]

I would try a different lube, and coat the inside of the neck, instead of or in addition to to the mandrel.

I use Redding’s dry lube which is basically graphite and their application method. They mix the graphite in with small balls, to apply by dipping the case neck into the graphite. It would be easy to duplicate.

I have found this to work very well, expanding a caliber at a time.

I also wonder if what you are seeing might be more visual than actual scratches. Something that was already there being polished.

 

[Benchrest Braxton]

I run into the same problem. I use lockease on a q tip. If I polish off the galled brass from the mandrel before I start, it expands the first 10-12 cases well but then I can feel the resistance change and the pull gets grainy. It’s very annoying I remove the mandrel and clean off the galled brass. I’m wondering if it’s the stainless. I’ve thought about turning a mild steel mandrel and hardening it but for the trouble it’s probably best if I just buy carbide.

black nitride mandrel from 21st century, fixes all of this, i got rid of my bare ones because of this

 

[Webster]

Hi all I've been using a particular brand of expander mandrel and the mandrel scratches brass every time doesn't hurt performance but really irritates me
I have Le wilson , K&M and 21st century available to me
What would be the best option be to mitigate the scratching
And yes I used lube

The mandrel would need small high spots to scratch. You said your mandrel is smooth. Only high hard particles can scratch. Maybe spin a bronze or nylon brush in each neck to clean up the carbon. At least I would try cleaning the necks to see if it helps. The necks themselves may have a bad brass texture from the extrusion process? You have to chamfer the case i.d. without burrs.

I lube with a synthetic or petroleum oil based oil from AutoZone. These types of oils have a much better film strength than some of the other concoctions others use. I worked in Engine oil research.

 

[rlporter507]

not actually related to OP's problem, but I was de-priming, cleaning in walnut, then annealing. I was getting some rusty looking residue when i would lube the inside neck with imperial. brushing would not get it all out. I contacted amp, and he told me it was burnt walnut residue, so now I de-prime, anneal, then clean in walnut and that took care of the problem. I think that cleaning in walnut after annealing gets all the loose carbon out also, could it be that there is some left in the neck the mandrel is dragging????