Making sizing dies fo PC boolits

[Gazz]

A friend gave me a big bag full of 400gr 45-70 boolits as cast. I want to try PCing them but realize I will have to size them before loading. One thought I have is to use an old reloading die that I can add an insert to with a proper .458" through hole - I do have a lathe and am capable enough to machine such a part or lacking a die with a suitable through hole, I could machine the whole thing, threads and all. Is cold rolled sufficient for this purpose or do I need to buy a hunk of 4140 or other half hard kind of steel? Thanks for helpful responses!

[shell70634]

I made a couple Star size dies out of mystery metal. I believe it was 1018. Polishing took forever.

[GregLaROCHE]

These work great and you can get all different sizes of inserts for all calibers.
I can understand if you would enjoy the project of making your own, but otherwise, to save time and materials this sizer and inserts is a pretty neat way to go.
If you make your own, you may want to consider hardening it afterwards. PCed boolits can get pretty tough.

https://noebulletmolds.com/site/product-category/sizing-tools/bushing-push-through-size-die/push-through-size-die-body/

[vagrantviking]

If you can fire tens of thousands of bullets through a barrel and not get appreciable wear I'm sure at least hundreds of thousands through a sizer should be no problem. No heat erosion to worry about either.

I'd use anything handy or something that machines nicely.

[Gazz]

Thanks for the suggestions! I do enjoy making stuff so there is that as well as most places show out of stock on almost everything related to ammunition.

[LaPoint]

GAZZ- you might want to try a Lee Sizing die. I have used them for sizing 9mm & 45LC PC boolits. They work great and they're inexpensive.
https://leeprecision.com/bullet-casting/bullet-sizing-kit

[NikA]

Whatever steel you can lay hands on will be acceptable.

I bought a 3' section of 7/8"-14 threaded rod for the purpose of making push-through sizing dies. Saves a load of time on the external threading operation. If I were to have to cut threads on one, I'd prefer to use 1144 for the machinability; this material would probably make the bore finish smoother as well.

Something like 4140 is probably going to require a lot of internal polishing.

[Conditor22]

+1 on the threaded rod.
this shouldn't be that difficult a project, bore a hole through a 2 3/7 inch section of the rod a little smaller than you want, enlarge the exit side of the hole 2 1/4
bevel/smooth a 1/8" entrance to the die, polish the interior of the die to your desired diameter.

the pushrod is just a shell holder base with a 1 1/4 rod that's several thou under the die diameter.

even with Lee and NOE sizers, I like to polish the entrance and slightly polish the inside to remove any machining marks, I feel they seize easier this way.

[pan957]

Buy a 7/8-14 long bolt off of Ebay and cut off the hex, drill, ream and polish. I made several neck sizing dies from bolts when I worked in a machine shop in the 1980's.

[mrmachinist]

4140 is easy to machine. Has a decent hardness, and a great general use steel. Just need carbide tools and finish at a high rpm. Polish with some 240grit and higher if you need and it can be mirror finished. If you have the tools for burnishing, you can get finishes in the 2-4um range.


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[NikA]

4140's surface finish after machining is going to be related to it's heat treat/work hardening state. Annealed 4140 is painful to machine as it will be work hardening as you cut. Q&T is going to be much easier to get a good finish on.

Problem is, if you buy something like a grade 8 bolt or B7 threaded rod, both of which are a low alloy steel similar to 4140 in composition (strength is spec'd, not composition, in these cases), the outside will typically be in a harder state than the core, because that's what's needed in fastener applications. However, we want a good finish in our sizer bore right through the somewhat softer core, which will be somewhat more difficult to achieve given the state of the material.

All depends on what material you start with. If you're going to be buying material for a one-off job like this, might as well buy 1144 and not worry about it.

[Gazz]

I found an expander die in my shop that was unmarked and after I got the button out, I found it was marked .45 Colt. The die has a generous opening so I can machine a bushing to fit and of course already threaded 7/8-14. The threaded rod that held the button had a bit of pretzel to it so it became my donor body. I bored out the internally threaded part (the top of the die) to allow passage of the sized bullet. In my bucket of short scrap, I found a 4" piece of .30 cal rifle barrel which is becoming the bushing - it is a bit tougher than mild steel it seems so that is good. I had to wait a bit to check my set of expansion reamers (at another shop) in the hopes that I could adjust one for a .457" hole but no luck, the smallest it will do is .468" or something close to that. I gotta get some paint powder on order (any brand or color that is better?) and find a toaster oven now.

[oley55]

These work great and you can get all different sizes of inserts for all calibers.
I can understand if you would enjoy the project of making your own, but otherwise, to save time and materials this sizer and inserts is a pretty neat way to go.
If you make your own, you may want to consider hardening it afterwards. PCed boolits can get pretty tough.

https://noebulletmolds.com/site/product-category/sizing-tools/bushing-push-through-size-die/push-through-size-die-body/

except for the backorder wait times. I ordered in late January and am still anxiously waiting...

[charlie b]

Back when I had machine tools I made several sizing dies and a couple of bullet seating dies. I just used the 7/8-14 threaded rod. It polished up just fine.

I started by sizing just at bore dia and then opening up slightly until leading went away (just polish it a bit more).

[Gazz]

After several tries and always going to big by .001" or more, I had success. I had an old B&D circular saw that had bad gears in it so I dismantled it repurposed the gear shaft which was some hard steel. I annealed it and carefully bored at high speed with a carbide cutter and it will push out a .458" slug. It is a bushing that fits in a modified expander die so I can make other bushings for different calibers. I received my powder paint from Eastwoods so now to find a toaster oven!

[Traffer]

4140's surface finish after machining is going to be related to it's heat treat/work hardening state. Annealed 4140 is painful to machine as it will be work hardening as you cut. Q&T is going to be much easier to get a good finish on.

Problem is, if you buy something like a grade 8 bolt or B7 threaded rod, both of which are a low alloy steel similar to 4140 in composition (strength is spec'd, not composition, in these cases), the outside will typically be in a harder state than the core, because that's what's needed in fastener applications. However, we want a good finish in our sizer bore right through the somewhat softer core, which will be somewhat more difficult to achieve given the state of the material.

All depends on what material you start with. If you're going to be buying material for a one-off job like this, might as well buy 1144 and not worry about it.

I use Grade 8 bolts all the time for dies...You are correct about the softer areas....The area just under the Head is the hardest. I usually use that end for the actual die diameter. It does machine harder but still within reason.

[highmountaincaster]

I’d use 12L14 steel, easy machining and threading. Accepts hardening though I don’t think it would be necessary. Cut with Hss tool bits it can achieve a very fine finish and requires minimal polishing to acquire a “glass like” smooth finish. It’s also very plentiful and priced right. eBay is a good place to find various sizes.