Expander mandrel on primed brass?

setter · Oct 17, 2024

I am going to try using an expander mandrel for the first time and I'm still new to reloading. I did a search in this forum and found a lot of good info. However, when someone asked: "The expander mandrel is the last step before seating the bullet?" and the reply was "Yes", that made me wonder whether I should take that statement literally since that didn't make sense to me. Wouldn't that be difficult with powder in the case since otherwise that would be the last step before seating?.
I have some primed brass and would like to use the expander (before proceeding with adding powder). Could there be pressure build-up when using the expander mandrel since the case is 'sealed' with the primer in place and wouldn't the mandrel actually create an air tight seal at the neck at the same time? Could that either cause the primer to pop out or loosen, and/or cause the case to bulge out?

David_h · Oct 17, 2024

You should be fine either before or after priming. The air is a compressible fluid so no worries on pressure from inserting a mandrel. Yes, I'd avoid using a mandrel after the powder charge is filled; those mandrels can be quite long.

Hugnot · Oct 17, 2024

No powder in case & no decap pin on expander.

I very cautiously wipe the inside of the neck with a slightly moistened small wad of paper towel or Q tip with Hornady One Shot lube & cleaner being careful not to get any of that stuff on the primer. After cleaning neck insides I place the primed cases neck down in the loading block. My reasoning is that the One Shot will facilitate passage of the expander thru the neck and cleaning the insides of the neck will remove all or part of the nitrate salts and other acidic deposits formed by powder combustion that will cause corrosion stuck bullets.

Just be real careful not to mess up primers with the One Shot - a blast of One Shot into the case will probably kill the primer for some time.

stazmania · Oct 17, 2024

The displaced air from the expander pressuring the primer is something to consider. I have new, primed brass that I was thinking about running through a SAC sizing die with an expander, to be sure of uniformity. Checking the primers after sizing would be a good practice. Thanks OP

lancetkenyon · Oct 17, 2024

Run them through the expanding mandrel. Primed or unprimed. No difference. I have done 10s of thousands each way.

NEXT time, run them through BEFORE priming. I think the comment of "last step before seating" should have been "last step before loading" (priming, charging, seating).

RegionRat · Oct 17, 2024

+1
Even if you consider that the starting pressure in the case is 14.7 PSIA, and you are squeezing the volume of the mandrel down into the tight neck, you won't hit the type of pressure that can affect a normal case, with our without the primer in place.

In theory, if that compression causes a primer to move, you have bigger problems.

Try it with your case, mandrel, and bare hands just to satisfy yourself some day.

MagnumManiac · Oct 17, 2024

Just a word on new brass and neck condition.
I run all new brass through a custom neck die and then through a mandrel before doing any loading. Necks on factory brass NEED to be sized IMHO.
I have found factory neck specs incorrect for precision loads, it is always too tight on interference.

Cheers.

std7mag · Oct 17, 2024

Wait.....

Is @setter talking about pistol cases, or bottle neck rifle cases?

Huge difference!

quandary · Oct 17, 2024

I will differ with one comment above. Never get one shot, imperial wax, whatever inside the neck. After you have run your brass through a tumble or ultrasonic you can run a brush on the inside of the neck. If you want to lube the the inside for expanding use graphite. You don't have to worry about cleaning that. You don't want the othe types of lube on the inside of your neck when you drop powder or seat bullets. Its a PIA to clean out.

MagnumManiac · Oct 17, 2024

quandary said:
I will differ with one comment above. Never get one shot, imperial wax, whatever inside the neck. After you have run your brass through a tumble or ultrasonic you can run a brush on the inside of the neck. If you want to lube the the inside for expanding use graphite. You don't have to worry about cleaning that. You don't want the othe types of lube on the inside of your neck when you drop powder or seat bullets. Its a PIA to clean out.

I agree 100%.
I have been lubing the inside of my necks with powdered graphite, mica powder and use HBN coated bullets for a long time.
These parameters have shrunk my groups for LR/ELR target shooting like no other operation has, not even running cases through expensive seating die electronics operated seaters, sure there IS a slight improvement of a tenth, but nothing like what the above does for consistency.
The thought of putting ANY type of case lube inside a neck, even for mandrel operation, makes me shudder.
Powdered graphite or powdered mica work just fine and needs not to be removed…

Cheers.

setter · Oct 17, 2024

std7mag said:
Wait.....

Is @setter talking about pistol cases, or bottle neck rifle cases?

Huge difference!

bottle neck rifle cases

Brathany · Oct 17, 2024

@quandary & @MagnumManiac - How do you apply your graphite to case necks?

MagnumManiac · Oct 17, 2024

Brathany said:
@quandary & @MagnumManiac - How do you apply your graphite to case necks?

With a calibre specific nylon brush, same sold for barrel cleaning.
A little goes a long way, the difference with/without is amazing, even when using expander balls…no screeching and smooth as silk.

Cheers.

Old Rooster · Oct 17, 2024

I use a q-tip to put a small amount of graphite in the neck.
I also use coated mandrels so they slip in the neck easily

Expander mandrel on primed brass?

setter

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David_h

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Hugnot

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stazmania

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lancetkenyon

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RegionRat

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MagnumManiac

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std7mag

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quandary

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MagnumManiac

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setter

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Brathany

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MagnumManiac

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Old Rooster

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