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Do you size 9mm cast bullets?


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A gentleman told me all 9mm-ish sized cast bullets should be run through a sizing die. I don't size .452 bullet and neither does he, but he said he believes it is a must for 9mm... He went on to say that most 9mm molds throw bullets that are from .001-.003 oversized, while the larger .452 molds throw bullets that are usually about .452-.4525 which don't need to be resized. Ever heard of this?



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  • 9 months later...

I know this is an old thread, but I keep thinking about it since reading it when I registered the other day.

Whether a 9mm bullet needs sized or not depends. Just like any other caliber or gun, the key with cast bullets is fit. The bullet diameter and gun's bore diameter must be suited to each other. Most people find it best with the bore and bullet the same diameter, or the bullet .001 over (although I often go .002 over for some guns).

Then we get into the problem of getting that fit. You have a mould and a bore to deal with.

First, the mould. A bullet mould might be advertised as making a .356 bullet, or perhaps it's model number starts with 356 (i.e. 356123) but that doesn't guarantee the bullets will actually be that diameter. Manufacturing tolerances vary, and some makers seem to make a lot of undersized moulds as the cherry (cavity cutter) wears. I have 9mm moulds that make bullets from .355 to .359. I use some .38/.357 moulds for 9mm because they cast a bit small.

We can also vary the diameter of the produced bullets ourselves. Changing alloys, casting techniques or temperature can vary the diameter of the bullets produced. The easiest way I know of to get a bigger bullet is to cast hot. If I need a larger bullet, I turn the furnace up a little higher and keep the mould hot. Likewise, dropping the temp and cooling the mould can give you smaller bullets.

The other half of the equation is bore size. There seems to be a variation in 9mm bore sizes, but they tend to run large from what I see. While .355 gets tossed around as "standard", only one of my 9mms slugged that size (Sig P-210). The rest are larger, with a couple at .358 (both HiPowers). You pretty much have to slug the bore of every gun you plan to cast for.

Before finding my guns' bores were a tad large, my 9mm bulllets were tumbling. I didn't have that happen with any other caliber, including centerfire rifles. and even .223 which can be a challenge. But with the poor match of big bores and standard (or smaller) bullets, the 9mms were frustrating.

So with bores varying, and the fact we can produce bullets of various diameters, it's hard to say 9mm cast bullets don't need sized.

I suppose that if you were casting for just one gun or guns with the same bore diameter, you could alter your casting technique (or moulds) to cast your bullets just the right diameter. When I try that, I get different results each time, so I just cast to hopefully be a touch larger than the biggest bore and size to where I need them.

The Lee Tumble Lube moulds supposedly produce bullets that don't need sizing. Like all other moulds: Maybe they do, maybe they don't.

I have two Lee TL moulds. One is a semi-custom .44 caliber, and it is just dandy as-is. But it was custom made to be big enough. The other one is a .45 and it would be too small except that the 1911 I use most has a slightly tight bore.

They vary in size like every other mould and Lee can't know what your gun's bore size will be, so Lee shouldn't be saying they don't need sized. But they can't hardly be sized anyway because sizing will wreck their lube bands.

I am happy with them in the guns I use them in, but I would not buy a Lee TL mould for any gun with a bore that's anywhere close to the large side of tolerances.

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I would bet with 95% certainty it's the bullet fit and not the WW softness.

I used to think harder was better but now I know fit is #1. There are numerous threads on the cast bullet forums about this, and it always goes the same way: Gun/bullet has leading; he tries harder and harder alloys; is about to give up then slugs the barrel and sizes bullet to match; leading stops.

If the bullet fits right, you should be able to use lead softer than WWs. This is assuming a bore that isn't rusted up or anything, of course.

I use regular WW metal in .357 up to at least 1,200 fps, and a little faster in a .357 rifle.

In rifles, I use WW metal but drop the bullets from the mould into a bucket of cold water to harden them some. I shoot those to 2,200 fps or a little faster without leading.

Going harder will often help, but it's more of a band-aid than a fix.

The commercial casters use really hard alloys for that reason. They know few if any buyers of their bullets will slug the bore, so they cast them as hard as the can to squeak by. It usually works unless they try to load them fast, so what the heck.

The best way to slug a barrel I know of came from a book Beartooth Bullets puts out.

He suggests using oval/egg-shaped fishing sinkers with the hole down the center lengthwise. The tapered ends let you start it into the bore easily, but the hole down the middle is the key.

Without the hole, a solid slug will squeeze down as it is pushed down the barrel then spring back when it comes out. This will give a false (too large) reading.

With the hole, the lead has a place to go when squeezed down, so it won't spring back when it comes out. What it measures is what it should be, or close enough.

They aren't very consistent, but generally:

#10 oval sinkers work for .30 caliber.

#9 oval sinkers work for .35/.39/.9mm.

#8 work for .45 caliber.

A little 1/2 ounce bag will hold five to ten sinkers.

I put a light coat of a light oil on the bore first. The bore should be good and clean too.

I use a brass rod that will won't fit a .30 cal but fits a .35/.38/9mm. I have some wood dowels for larger bore rifles, but would rather have brass or aluminum.

After getting the slug started, I go to a fairly heavy hammer so I can give it two or three good hits (pistol barrel) instead of a bunch of taps. I think that works better, but you need to be careful that your last whack doesn't send the rod sailing on through so the hammer hits the muzzle or chamber. Tape wrapped around the upper end of the rod makes a good "brake".

Try to catch the slug in something soft. Carpet at least.

I dry any oil off the slug with a paper towel and measure it with micrometer calipers. I keep the slug in a ziploc bag that I label with a black marker, telling the size and what gun it was used in. I write the numbers down on paper too, but I lose them and have to refer to the bag.

Once I know what the bore slugs, I have a starting point. I usually size .001 over and go from there. I've found it's usually better to err on the large side. I know some people worry about an extra .001 raising pressures, but I haven't seen that it does enough to matter with cast bullets. I size my .44 bullets to .432 , which is pretty big for the caliber (not all moulds will cast that big) because my Ruger 77/44 carbine likes them that way. That makes them a tad bigger than needed for my .44 Special, but it doesn't seem to effect pressures much if at all. A pressure test fixture might say different, but I'm measuring case head expansion and don't see it.

BTW, when I have bullets that get used in guns of widely different bore sizes, I size the bullets big using the lubesizer, then when I need smaller ones I run them through a Lee "push-thru" die than comes with the Lee Lube & Size kit.

Two or three more things:

-Even though your sizing die might say .357 (for example), the sized bullets might measure different. The die might be off, or the bullet might spring back.

You just about have to mike the bullet after sizing and go by that.

-I found that case mouth crimp was very important with 9mm cast bullets. The 9mm case is hard to eyeball on crimp because of it's slight taper. What looks like a light crimp that just straightens the case mouth might be a pretty aggressive crimp that damages the bullet. Go easy, start with less crimp then you think you need and work up from there. Don't use any more than you need to keep the bullet in place in feeding.

-You might have to compromise on size. With some 9mm guns having bores that are larger than we expect, you may end up needing a bullet as big as .358. The problem is that the case will then be so large around the bullet that the rounds won't chamber easy if at all. You may have to drop down in bullet size until the cartridges chamber, even if you give up a little accuracy.

And in a similar vein, the expander of most 9mm dies might not open the case up more than about .356, so if seating a larger bullet than that, the bullet might open up the case. That's not good for the bullet and might size it down a little. If you have one, you might need to use the expander from a .38/.357 die.

If by chance you gun is closer to the supposed standard of .355, you will probably avoid most of this aggravation. But if it's on the large side, you might. I have had to do some of these things for some guns, and others for different guns, but not all of them for a single gun. Yet.

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