Using expander mandrel for dented case mouths

[PinesAndProjectiles]

I've been running my Nucleus in a few matches and I run it fairly hard. When I do this, the extractor flings the cases into the side of the action which leaves the case mouth slightly dented.

I've put a piece of adhesive backed velcro (the soft side) on the action where it hits and that helps, but it still leaves a small flat spot on the case mouth.

I'm looking for a mandrel to run through the case mouth prior to FL sizing to round out the mouth as I dont use the expander ball.

Any ideas where I could get a mandrel that's oversized to correct the mouth before sizing?

 

[pmclaine]

21st Century

http://www.xxicsi.com/

 

[918v]

Have you tried just FL sizing the cases? The act of sizing will generally pop the case mouth flat spot right out. You can also use a decapping rod to push it out. Or needle nose pliers.

 

[PatMiles]

Use a bullet to tweak the flat portion out.

 

[Afkirby]

Are you using a bushing die? A regular FL die without an expander would give you tons of neck tension.

 

[Sheldon N]

Any ideas where I could get a mandrel that's oversized to correct the mouth before sizing?

Sinclair Gen II expander mandrel die, 21st century titanium nitride coated mandrel.

Personally I like the workflow of FL sizing to a neck tension that's a couple thou too small, followed by expander mandrel to bring it up to final dimensions. You want the "turning" mandrel if you are after 0.002 neck tension. The "expander" mandrel is 0.001 neck tension. I do it with a non-bushing FL die since that's generally going to be less runout, but you could do it with a bushing die too.

If you run a mandrel prior to FL sizing the mandrel will be several thousandths too small since the case neck is already expanded from being fired. It will take out a major dent but won't make the neck perfectly round.

 

[FatBoy]

K&M sells mandrels that allow you to pick your NT. I use these on all brass except Peterson as everything has dented case mouths when bulk shipped. It allows NT to be pretty consistant without neck turning as well.

 

[PinesAndProjectiles]

I'm using a Redding Type S but I am not using the expander ball because, well it defeats the purpose of the bushing.

I may have another die that I can put the expander ball into and just lower it enough to round out the mouth before sizing.

Thanks for all the input, everyone. I'll give this a shot and if it doesn't work, may need to get the mandrel from 21st Century.

 

[PinesAndProjectiles]

Tried the expander ball method with no luck. I measured some cases, and ultimately, I would need a mandrel with an OD of .2675, which is the ID of the mouth after firing.

And the 21st Century tool is only +.002, which isn't quite enough.

 

[918v]

Lee makes a Universal Expander which is kinda like a tall version of a pistol expander with two conical expander inserts. That will definitely fix the dent. But anything round that fits down the neck will work just as well.