Question on Turning Down Handgun Expander

[ejcrist]

I have a set of RCBS 32 Long/32 H&R carbide dies and the die that does the expanding/flaring of the case mouth has an expander that mic's at .311." At first thought that doesn't seem too bad but I have a couple of 32 H&R's and one requires boolits sized to .312," and when loaded using this die the crimp and neck tension are definitely too little. As a result I'd like to turn it down to .310" or .309." I've read before that it's extremely easy but I've never done it before. What do you do, just chuck it in your drill press and use a mill file on the case expander part before the section where it flares the case mouth? Or do you use something lighter like emery cloth? Any info would be greatly appreciated. I didn't see much about doing this on the web.

[DougGuy]

File is too coarse. Emery cloth would work, you can hold a piece of wood behind it to direct where most of your work will be done. It is real easy to take too much off the bell that flares the case mouth. A drill press will probably work.

[bangerjim]

Best done in a lathe. Carbide is hard and about the only thing you can cut it with is harder carbide or diamond lapping compund.

Drill press? Mabe, but you have no real control of accuracy and run-out. It may work.....or you may be buying another die real soon!

I would suggest you find a local buddy with a good lathe and buy him some beer!

banger

[gloob]

Good answers.

But I bet your sizing die is the limiting factor. I would take pains to investigate before turning down the expander.

Try barely flaring the cases enough to start the bullet. Use a universal flaring die, if you have one. Or make do with what you can find around the house. If you still don't get good neck tension, it is the sizing die. I have no problems with neck tension using an expander the same size as the bullet. If your sizing die is the problem, making the expander smaller won't do anything, at all - helpful. But if you get a new sizing die, your expander might not work as well as it would have before you turned it down.

Another tipoff of an oversized sizing die is if you get poor neck tension on only some cases, but decent neck tension on others.

A properly sized expander plug from the factory is a rare bird. Don't screw it up for nothing. I custom order/make plugs to be less than 1 mil smaller than my boolit. If I got an expander plug like yours from the factory, I would be counting my blessings.

[country gent]

Chances are the expander is hardened steel not carbide the carbide dies have a "ring" sweated into the base of the sizing die is all the carbide in them most of the time. You can polish expanders down pretty easily and accuratly. I use popcycle sticks ( you can buy 100 at the grocery store for a couple bucks. start with 400 grit glie a piece to a stick with contact cement or rubber cement. then the same with 600 grit and 1000 grit. Spin expander in lathe or drill press and lightly strat working with the 400 stick checking often then 600 grit and last 1000. finish with soft felt and flitz or simichrome metal polish. WOrk slowly and check size often with good michrometers. A little light oil on the paper makes it cut smoother and helps keep it from loading up. It is easy to do and working carefully you can track how much is coming off. The risk is going to far and ending up to small.

[gloob]

The risk is going to far and ending up to small.

And AFAIC, his expander plug is small enough, already.

[EDG]

First call RCBS and see if they will send you an expander of the right size.

If not you can procede with polishing yours down.

Use a micrometer and leave it a little larger than you think you need and test it.

If it is not small enough proceed to make it a little smaller.

Remember your micrometer is your friend. Use it often. Check for taper. You are learning a useful skill that will transfer to other projects.

For the first 2 minutes or so use 220 grit silicon carbide wet or dry paper wet with a very light oil. A light gun oil works fine. Back up the paper with a steel scale or flat bar so that it cuts level and you can control it. Then switch to 320 or 400 grit . Again use wet and backed up with a smooth rigid bar or metal scale.

To get a nice finish use 500 grit to 600 grit paper wet. After you polish the 400 grit marks out finish by polishing dry. By know you know how do this like a pro.

[Litl Red 3991]

I have a set of RCBS 32 Long/32 H&R carbide dies and the die that does the expanding/flaring of the case mouth has an expander that mic's at .311." At first thought that doesn't seem too bad but I have a couple of 32 H&R's and one requires boolits sized to .312," and when loaded using this die the crimp and neck tension are definitely too little. As a result I'd like to turn it down to .310" or .309." I've read before that it's extremely easy but I've never done it before. What do you do, just chuck it in your drill press and use a mill file on the case expander part before the section where it flares the case mouth? Or do you use something lighter like emery cloth? Any info would be greatly appreciated. I didn't see much about doing this on the web.

I've been working with my 32mags for a couple of months now. And fiddling with the same type of problem as you are. Good thing is that I've got a couple of different sets of dies to mix and match and have been able to match up dies that don't cancel out each other.

I discovered that my brass was actually sizing down my cast boolits after they were sized to match the pistol. The discovery showed that brass can easily apply neck tension that'll overcome cast boolits that are alloyed to obturate at the lower pressures you find in some calibers. (No matter they call it a "magnum" it's far from being one.)

A couple of my 32 pistols leaded badly. The commercial cast being used at the time were "extra hard to stop leading". So I bought some moulds and solved that problem with 9-10 BHN boolits. Got a lot better accuracy too. Then I discovered that although I was sizing to match the cylinder throats, the cases were cancelling out my sizing. If the alloy hadn't been soft enough to obturate, the leading might have not gone away and the accuracy might not have improved.

So I decided to size the brass less and use an expander that matched and the results were the most accurate pistol I've ever owned.

From what I've seen so far, the least thing that would worry me would be my brass isn't gripping tightly enough. If I were you, I'd pull a couple of boolits and measure to see if they kept their original diameter or if they'd been resized by the cases when seated.

[Litl Red 3991]

First call RCBS and see if they will send you an expander of the right size.

Just a day or so ago someone said that RCBS sells a number of expanders of different sizes for the 32mag. I spent about a day searching the internet and RCBS' website for them. Hopefully someone on these forums will have a line on how to find those suckers. RCBS' website seems to have no mention of them.

In fact, my RCBS Cowboy dies for 32Long/Mag were shipped with two different expander punches in the box. Both were marked "314" and both measured the same .313" diameter. None of the parts listing or paperwork mentioned anything about sizes of expanders and in fact, didn't happen to list a part number for the one pictured. It looks to be unusually difficult to even purchase "issue" RCBS expanders, much less buy optional sizes.

[gloob]

You might find something you can use in NOE's list of rifle plugs. The rifle plugs might be just a tad long. But for a revolver, I suppose extra length on the expander will work fine so long as the plug doesn't start to bulge out the caseweb before it starts to flare.

http://noebulletmolds.com/NV/index.p...9e1dvopvkokcf6

There are also a couple of machinists around here that can make a plug to your spec's, made to fit either, say, an M die body or Lee die.

[gloob]

^That's only possible with bottlenecked cartridges. OP described his dies as carbide, i.e. carbide sizing ring.

[Litl Red 3991]

The dies he's talking about are from RCBS and are in a 3 die set. The Sizing Die has a carbide ring that sizes one dimension from mouth down and a primer punch that does not have a button. The Expander Die has a solid punch inside that expands the case as it moves into it and flares the mouth in the last bit of movement. The seater/crimper etc.

RCBS sells two types of sets. The most recent is the Cowboy dies that are advertised to be more appropriate for SASS/CAS/cowboy action shooting, which is done with lead bullets only. No jacketed bullets. They actually are rather silent in the advertising about what is different and why. And no dimensions given.

[mdi]

Got me! I guess my thinking was on a 30-06 die I'm having trouble with right now. My most sincere apologies...

[EDG]

You can probably find those expanders in the parts lists of a die set. They may not be identified by diameter. I doubt that they are are marketed as a retail parts for separate sale. I have never seen them advertized as a spare. Redding does not advertize their expanders as spares either but they make them in different diameters. RCBS will make an expander for the .30 Carbine that is probably .306 or .307. All you have to do is call and ask. If they do not have them marketed on the net it is more likely that RCBS is focused on selling die sets since they tend to provide replacement parts free of charge.

Just a day or so ago someone said that RCBS sells a number of expanders of different sizes for the 32mag. I spent about a day searching the internet and RCBS' website for them. Hopefully someone on these forums will have a line on how to find those suckers. RCBS' website seems to have no mention of them.

In fact, my RCBS Cowboy dies for 32Long/Mag were shipped with two different expander punches in the box. Both were marked "314" and both measured the same .313" diameter. None of the parts listing or paperwork mentioned anything about sizes of expanders and in fact, didn't happen to list a part number for the one pictured. It looks to be unusually difficult to even purchase "issue" RCBS expanders, much less buy optional sizes.

[bbqncigars]

IIRC, (on the road now) my RCBS 45-70 Cowboy dies have two different diameter expanders that are marked as such.

[Litl Red 3991]

You can probably find those expanders in the parts lists of a die set. They may not be identified by diameter. ..........

The parts list in the die set??

......In fact, my RCBS Cowboy dies were shipped with two different expander punches in the box. (and came with a parts list) .......... None of the parts listing or paperwork mentioned anything about sizes of expanders and in fact, didn't happen to list a part number for the one pictured. ....