Expanding 9mm for cast what do we need exactly?

[oldhenry]

I guess ignorance is bliss or I'm just lucky. I load on a Dillon 550 with Dillon dies. The stock expander on the powder measure works for me after I polished it with white rouge on my felt wheel + I size boolits to .357.

I have 3 different 9mm molds, but use the MP130 (they weigh 135 gr. with my ally) the most. After I went to the .357 boolit sizing they all plunk just right & I have not experienced any leading. I use BAC lube & this combo seems to polish the bore.

The SR1911 is throated from the factory.

Henry

[gloob]

I only use range pick-up brass for 9mm and I've accumulated a lot. I use 3-2-95 alloy and I size my PC'd 9mm to .357. I size 9mm brass with a LEE carbide die and then measure each case and cull any case that is .752" or longer and those that are .748" or shorter. In my experience, 9mm brass lengths of .758" and .740" are not uncommon with the great majority of my culls to the short side. My cull rate is about 15% for brass that I have not previously processed. After measuring I sort 9mm brass by headstamp because I like uniform neck tension and at this point I cull weird headstamps.

Since no one has mentioned it, case length matters to me when I go to expand a case mouth. I set my expander flare for .750" long brass and at that setting a piece of .744" brass (for example) will be insufficiently flared and will shave lead.

I expand 9mm brass twice. First, with a dedicated Lyman M1 die with a "38P" expander plug (the nose of my expander plug measures .356"). I expand the 9mm case with the 38P to the maximum depth where it will still freely plunk into my Lyman 9MM chamber gauge. This expands the case to .356" for the full seating depth of the boolit. At this point the 38P plug will not flare the case mouth. I then use a second dedicated Lyman M1 die with a "38AP" expander plug ( the nose of my plug measures .354") to flare the case mouth.

More work, yes, but I like the results.

IMO, the step flare reduces the headache of using unsorted brass. Just set the step flare to barely flare your shortest cases. The longer cases will have a longer flared section, but it will still have the exact same amount of full neck tension on the seated bullet.

If the longer cases actually need some taper crimp to plunk, then set your die to apply bare minimum taper crimp to these longer cases, and if it doesn't touch the shorter one? Don't matter.

With a conventional flare die, the longer cases will get the mouth flared out too wide like a trumpet when you do this.

[gwpercle]

My expanding 9mm cast boolits came by way of :
A NOE boolit mould ... 358 -124- TC- GC (Gas Check)
cast the boolit soft ... bhn 8-9 , no harder .
Install the gas check , size .357" , Lithi-Bee Lube ,
and drive them fast +1000 fps ... 1166 fps with 5.5 grs. Unique does nicely .
They flatten out nicely ... like a JHP .
Be careful seating the soft boolits ... no need for casting those pesky hollow points.
Gary

[jetinteriorguy]

I use the NOE powder through M-type expanders in all my pistol loads and couple them with a Lee Pro Disc for excellent results. I’ve waited for them to make these again for years and so happy when they started making them again. If you have any questions about them and what size you need just call them, they are one of the most helpful companies you’ll ever deal with and make high quality products.

[GregLaROCHE]

The best thing about NOE expanders and sizers, is that they are inexpensive and you can have different sizes to try out. Whenever I start with a new calibre, I always get the size above and below what I think I need.

[gloob]

The best thing about NOE expanders and sizers, is that they are inexpensive and you can have different sizes to try out. Whenever I start with a new calibre, I always get the size above and below what I think I need.

Absolutely prefer NOE expanders, too.

But Lyman M die plugs have a threaded section that screws into the M die body. This is small enough to chuck in a hand drill, if you have one that runs true enough to use as a lathe. You can turn the plug down with a dremel and a cutting disc, then smooth and polish with sandpaper, if you want to make one in a size they don't sell or to do your own experiments with expander size.

For instance, I couldn't find anyone who makes a 401 expander. At least when I wanted mine. After speaking with Lyman to see if they had something bigger than the 398 expander I purchased from them, they sent me a 404 for a different caliber. I was able to turn it down to 401 with a 404 step flare, and shorten it to the correct length for my boolits. Tip, make a distinct groove, first, to ensure you get a good shoulder on the step flare. Doesn't matter if it's a little too deep or not. Just make it slightly deeper than you need.

Most common battery drills don't run this true. Most AC corded drills do, IME. Must be something about how the motors are made.

edit: just checked NOE's site. They make a 405/401 now. And even a 406/402. Looks like more cast boolit reloaders are catching on to using full size expanders rather than the old standby of going minus 2.