Expander mandrel issues

[moe africa]

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

 

[marchboom]

The brands you listed are all good. As long as they're clean I can't imagine what could cause the scratching. What is the size difference between the pre-sizing neck I.D. and the mandrel you use? Might be too much expanding difference.

I use pin gauges and then polish them. Prior to sizing I chamfer the neck with a 22 degree tool and brush out the necks with a nylon brush. Lube is homemade lanolin and alcohol.

 

[moe africa]

The brands you listed are all good. As long as they're clean I can't imagine what could cause the scratching. What is the size difference between the pre-sizing neck I.D. and the mandrel you use? Might be too much expanding difference.

I use pin gauges and then polish them. Prior to sizing I chamfer the neck with a 22 degree tool and brush out the necks with a nylon brush. Lube is homemade lanolin and alcohol.

The difference is about a thou

 

[ShtrRdy]

Try polishing the mandrel with some 1000 grit paper. You can spin the mandrel with a drill as you polish.

 

[moe africa]

Try polishing the mandrel with some 1000 grit paper. You can spin the mandrel with a drill as you polish.

I've tried flitz and iosso ( probably finer than 1000 grit) it comes out looking mirror smooth but still scratches

 

[marchboom]

The difference is about a thou

That definitely shouldn't cause any scratching. Make sure you do a good chamfer on the case (then brush) and use a good lube. That's the only thing I can think of.

 

[ShtrRdy]

I wonder if you are simply seeing microscopic lines that appear as scratches. Maybe try sharpening the tip of a toothpick and slide it across the scratches to see if there are actually grooves?

 

[LVLAaron]

Is it scratching, or is the mandrel getting galled and picking up brass?

 

[Straightshooter1]

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

When and how often do you trim and chamfer your cases?

It could be the chamfering tool is not sharp and not making a clean cut leaving a burr on the chamfer???

 

[powderbrake]

I have found that trimming the brass without chamfering the ID will allow tiny brass particles from the burr to get between the case and mandrel, which cause scratches.

 

[Old Navy]

Hard brass will cause that. Been there and done that. Lapua sized six times. Annealed the brass. Problem solved. Brass was harder to resize also.

 

[DonkeyHote]

I use a method that eliminates the galling in my brass and mandrel, it serves two purposes, prevents gulling and cold welding of the bullets to the case. After annealing and sizing and tumbling the bras, I apply neolube #2 to the inside of the necks.

Let it dry and prior to loading the cases I run the mandrel in the necks. Done a few thousand this way without any marks on the mandrel or the case. If anything the mandrel developed a mirror like finish over time.
May not be for everyone, but it works for me....

 

[moe africa]

Hard brass will cause that. Been there and done that. Lapua sized six times. Annealed the brass. Problem solved. Brass was harder to resize also.

I anneal every time

 

[bozo699]

I anneal every time

MOE,
Take a jewelers loupe and look at the mouth of your cases that you have ready to expand to see if you do have burrs left from your chamfering process
Wayne

 

[KMart]

I anneal every time

If you don't tumble your brass AFTER annealing, there is oxidization left inside the neck from the annealing process. That oxidation will cause the scratches.

 

[butchlambert]

2 things that I do and is different than most. I fireform without a bullets first which leaves very little to expand. 2nd my expander is carbide.

 

[Benchrest Braxton]

i like the black nitride mandrels from 21st, use the turning mandrels (2 thou tension)

 

[6.5 forever]

If you don't tumble your brass AFTER annealing, there is oxidization left inside the neck from the annealing process. That oxidation will cause the scratches.

I believe this is the problem....

 

[moe africa]

If you don't tumble your brass AFTER annealing, there is oxidization left inside the neck from the annealing process. That oxidation will cause the scratches.

Tried it Didn't help

 

[William Vogel]

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.