Expander Mandrel - Scratched brass

[KMart]

Another thread about NEW Lapua cases having scratches on them and curding up sizing dies and mandrels in this case?
Run new Lapua cases through a vibratory tumbler using walnut media for about 4 hours before doing anything to them. This will clean off the oxidation off of the case necks left after Lapua anneals in the final step.
After about 4 hours of tumbling, this problem will go away. I have been doing this with new Lapua brass for years and I never have a problem.

 

[memilanuk]

I have fought a running battle with new Lapua cases for years on exactly this. Especially the brass loading on expanders (mandrels and otherwise). Forget about loading them 'straight out of the box', as the seating force required was beyond ridiculous.

Then about a year ago, I was talking with someone at a local match (a Service Rifle shooter, of all people) and he'd called Lapua about it and said their tech support told him pretty close to the same thing: tumble them for a couple hours in *dirty* media to get rid of the oxidation on the insides of the necks and ease seating forces considerably.

Of course, I haven't needed to cycle thru *new* brass between now and then... but it's surely on my 'to-do' list next time I do

 

[Straightshooter1]

Vibrating tumbling with rice does a very good job of not only cleaning, but also leaves a light coating that does well as a lubrication in the necks.

 

[Tony1320]

I have fought a running battle with new Lapua cases for years on exactly this. Especially the brass loading on expanders (mandrels and otherwise). Forget about loading them 'straight out of the box', as the seating force required was beyond ridiculous.

Then about a year ago, I was talking with someone at a local match (a Service Rifle shooter, of all people) and he'd called Lapua about it and said their tech support told him pretty close to the same thing: tumble them for a couple hours in *dirty* media to get rid of the oxidation on the insides of the necks and ease seating forces considerably.

Of course, I haven't needed to cycle thru *new* brass between now and then... but it's surely on my 'to-do' list next time I do

This is what I'm going through. last year I had time to fireform cases before matches this year I just dont have the time. I thought I would run a mandrel through virgin brass to open them up so I could load and shoot since I have 500 virgin cases for the year

I will try tumbling the next box in walnut media

Thanks everyone for the help

 

[KMart]

I have fought a running battle with new Lapua cases for years on exactly this. Especially the brass loading on expanders (mandrels and otherwise). Forget about loading them 'straight out of the box', as the seating force required was beyond ridiculous.

Then about a year ago, I was talking with someone at a local match (a Service Rifle shooter, of all people) and he'd called Lapua about it and said their tech support told him pretty close to the same thing: tumble them for a couple hours in *dirty* media to get rid of the oxidation on the insides of the necks and ease seating forces considerably.

Of course, I haven't needed to cycle thru *new* brass between now and then... but it's surely on my 'to-do' list next time I do

Thank goodness Lapua recommends "dirty" media. I haven't had new clean media in about 5 years. When the tumblers media level gets low, I scoop out about a red solo cup full and toss it. Add new media to my desired level, turn on the tumbler and add DuPont #7 Auto body polish and mix.
Clean walnut media is way over rated.

 

[BenPerfected]

Seems to me that if your neck thickness is close to perfect +/- .0005, this will play a big part of consistent neck tension. The K&M seater press & mandrels & annealing services like DJ’s Brass can both help you with consistent neck tension. How much impact to accuracy do you contribute to neck tension?
Big, medium or BS?
Ben

 

[ppaul]

Never had a problem with scratched necks with new Lapua or any other. My prep work is; full length size, turn to cleanup, gotta get some oil in the neck for lube, after turning polish neck w/ 0000 steel wool on a bore brush. Clean case with solvent to remove oil, resize neck and then lube in side with graphite on a bore mop. Mandrel size neck. Never a scratch!

 

[Uncle Ed]

My expander mandrels are black and have a coating of Imperial graphite that is nothing more than finely ground carbon. And if you wet tumble and use this neck lube, it will replace the missing neck carbon removed during tumbling.

Neck turning requires oil or a thicker lube so the case neck floats on a film of lube just like your cars engine bearings.

 

[muleystalker]

You stated you want to start using an expander mandrel and that you bought a 21st Century nitride turning mandrel. Thats not made for expanding the brass, its made for the case to ride on while neck turning and before you neck turn on it you are supposed to use their expanding mandrel first. It could be you are using the wrong mandrel that was not made to expand brass but for it to center the case as you turn them. Just a thought. I know my 21st Century power lathe came with a neck turning mandrel and a expander mandrel and die.

 

[natdscott]

Surrrre is easy to keep carbide clean....