For a dillon 550, 350 legend powder thru expander dimensions?

[mulespurs]

Ok so,
tommorow I am going out in my shop to my trusty lathe to turn out a new powder thu expander die for my 350 legend.

My Lee 200 gr gc bullets are sized .356 thru my new to me star luber. Finially found 4 at a gun show last year, and bought a pair. Makes lubing/sizing kinda fun for me.

Any how I need a dillon style powder thu expander , trying to be thrifty and use my shop stuff, I want to turn one out.

The lyman M die dimensions I have are .3528 on the initial diameter that goes in the case neck.

the 2nd diameter is .3577 I'll call it for the M step.

Any opinions on what adjustments I might make in diameter? Let's call the small diameter A and the 2nd one B.

And what kind of length would you put on dim A and B, so I don't cut it too short?

Then I need a 9mm one also, same dimensions again except oal?

Thank you for your support
mulespurs

[mulespurs]

Could someone please fix my error and move this thread to thr reloader section?

[garandsrus]

Your dimensions should be good. I might make the larger one .359 to .360. There is a little spring back in the brass and you may end up wanting your bullets to ba a couple thousandths larger. The length of the smaller diameter should be about 1/2”. The larger diameter, about 1/4”. You will only use about 1/8 of the larger diameter, but making it longer doesn’t hurt anything.

Don’t forget to put a taper on the end of the expander to help it enter the case mouth.

How are you going to cut the inner taper on the die? I use a 7 degree reamer to cut it. I also sometimes use a very small boring bar if I am getting chatter from the reamer.

Have fun….

[mulespurs]

The taper on the top of the die I cut with a larger center drill, don't know the angle, but powder should flow thru it.

[sigep1764]

I had Lathesmith cut my expander wider but a little shorter. The first length is about 1/4 of an inch and .358 in diameter. The step is .360 and a little less than 1/4th of an inch. As said before, brass has a bit of spring back, about .357 for the first part after expansion. Gives a little boolit tension but it doesn’t swage the boolit down. This is for 9mm. More importantly, what does your 350 Legend slug at? I’m almost certain you will need .358 or .359 boolits.

[garandsrus]

The taper on the top of the die I cut with a larger center drill, don't know the angle, but powder should flow thru it.

Most center drills are 60 degrees, so 30 degrees per side. That will give you a pretty quick taper. I don’t know if it will cause powder bridging, but you will want to check as it might. It will depend on the type of powder also, ball vs stick vs flake.

To check, hold the expander over a container of some type and try dumping a case full of powder into it pretty quickly. That will tell you if it will/can bridge. If it does, you can use a small boring bar to cut a taper inside the funnel.

[Kriek]

I use a 60 degree centre drill for the powder thru expanders that I make. I haven't had any problems with it. One thing that you van do is to polish the ID, but that will just be preference, not necesity.

Sent from my BV9900E using Tapatalk

[mulespurs]

I don't know what the barrel slugs at. but it has shot hundreds of .356 bullets with a gas check and powdercoated.

Just aquired a star luber and now have some lubed ones as well.

I had some retina surgery last Jan and still can't see as well as I need to for a good acurracy test.

I might have to loan it to my good buddy, who always shoots better than me, and have him get some answers for me.