.356

[weasel 21]

Why does lyman & other loading manuals always recommend 356 as the size for 9mm cast. I have had nothing but trouble in my quest to shoot a non leading bullet. I am now sizing at.358 to test.

[dragon813gt]

Because nominal bore is .355. If you have a tight chamber anything larger than .356 probably won't chamber. There is no one size fits all for cast bullets. I have a CZ that prefers .358 and a Walther that won't chamber anything over .356.

[AtomHeartMother]

You really need to slug your barrel to know for sure. A lot of newer 9's run a little big. I run 357's in my Ruger...it slugs at 3565.. Just as important, be sure you're not case swaging when you seat/ taper crimp your cases. 9mm brass can be bullet swaging little ********.. Load a dummy round then pull the bullet and measure it. Mine would case swage a 357 boolit down to 355 or even 354-leading city.

[Motor]

Because nominal bore is .355. If you have a tight chamber anything larger than .356 probably won't chamber. There is no one size fits all for cast bullets. I have a CZ that prefers .358 and a Walther that won't chamber anything over .356.

I like this answer.
I have slugged a couple of my 9mm and found both to be .355" but the 9mm can be a bear to cast for. Since I use a Lee tumble lube boolit, which many have had problems with in the 9mm x 19, I use them as dropped which is typically in the .358" diameter range. My pistols work great with this combination. My loads are low end target loads.

It's easy to tell if you are going to have any chambering problems. You can either remove your barrel, if possible, and do the "plunk test" of if your pistol has a fixed barrel make a couple dummy rounds and use them to test the fit.

Motor

[MT Chambers]

2 words: trial and error.

[Big Boomer]

Recently purchased a new concealed carry piece, a Sig P938. Already having a Lee 6-cavity 356-125, I decided to give that boolit a try in the little Sig. The boolit drops from the mould at about .3583 according to my Starret mic and my Star lube/sizer sizes it down as it lubes the boolit to .3581 (this is a Star .357 sizing die that I reamed out to .358 and polished to .3581). Tried loading a couple of rounds and doing the plunk test and it worked fine. Have since fired a few hundred rounds with no leading. As MT Chambers put it so well: 2 words: trial and error. While I use Sierra 115 gr. jhp bullets for carry, my practice rounds are lead plus the Sierra bullet as needed practice dictates. Big Boomer

[DrCaveman]

My 9mm likes .356" just fine, it is more than 001" over bore size (polygonal tapered).

Those same manuals often recommend .452" for 45 colts and ACPs, but a lot of us go larger. Hence, boolits that drop at .452" arent ideal for those guns, so a lot of lee, lyman, and rcbs moulds simply cant deliver. Time to go custom (accurate, Noe, etc...) or maybe jump up a size... Like, use boolits designed for 38/357 guns for your 9

[DrCaveman]

I should add something i only discovered a few months ago: just because you are sizing a boolit to yay diameter doesnt mean the boolit is all that diameter. I had kept measuring my 358429 boolits opposite the seam, and decided they were a nice .3585". After a frustrating amount of leading, i went back and saw that the seams were about .3565". No wonder the leading. A new boolit, with a true 3585" diameter has eliminated all leading. Sweet sweet glory

Yeah, dumb and regretful, but hey, we all make mistakes and learn from them

[bedbugbilly]

I experienced pretty much the same thing as DrCaveman did. I was using a Lee 356-120 TC. I didn't get much leading but I could see a little after a couple hundred rounds through my SR9 - and accuracy was not what I wanted. In careful checking, I discovered the boolits were a "tad" off - i.e. not fully concentric. I was also shooting that boolit in 38 special but wasn't satisfied either - funning thing is that I never got leading in my 38s.

I switched and starting using boolits from my Lyman 358-242 RN mold - 121 grainish - they work much much better "as cast" and they fall at right around .358 or a tad over - still work well in my particular SR9. No leading and accuracy improved greatly.

I will say that I tried sizing .356, .357 and usually my Lee 356-120 went through the sizer with very little resistance. I cast with "range lead" so I do check from batch to batch - if the alloy drops 'em much over .358 I'll size to .358 but rarely have to do it.

Every gun is different. MTChambers sums it up very well! :-)

[Shiloh]

I've only seen about 8-10 slugged 9mm's over the years. Not a one of them slugged at .355.
.356 and above were the general rule. I need .358 for best accuracy.

SHiloh

[N21911S]

As mentioned above, the combination of case wall thickness, bullet diameter, chamber and barrel diameters all are way scattered on various 9mm pistols. I ran across a S&W 659 that simply would not chamber rounds that a Witness enjoyed.

[MtGun44]

The majority of 9mms shoot best and don't lead with .357 and .358. No explanation for the large number
of folks still trying .356, and IME all the Lyman ammo info shows undersized boolits. AND sometimes their molds
cast undersized boolits.

Bill

[rsrocket1]

I size my 9mm boolits to 0.356" and need them that narrow. My S&W M&P 9 and Shield 9 barrels have narrow throats and tight chambers. 0.356" barely fits in there and anything bigger won't let the slide close and it's not because of the rifling, the lands don't engage for quite a bit deeper.

My Lee 356 molds drop at 0.358" and powder coating brings them up to 0.360" which is fine because I can size the boolits to 0.356" for the 9's and leave 'em be for my 38/357.

The great thing about casting is you can beagle the molds and/or PC to make the boolits bigger or size them down to make them smaller (by a couple thou at least).

[dkf]

A mold that drops .356 is worthless to me. This is why I have learned to avoid certain makers of molds and buy certain makes of molds. Sizing dies are made for a reason.

[rsrocket1]

A mold that drops .356 is worthless to me. This is why I have learned to avoid certain makers of molds and buy certain makes of molds. Sizing dies are made for a reason.

Send them to me, I'll pay postage.
[smilie=s:

I don't really need any more 9mm molds, but what the heck.

[gwpercle]

I bought two Lee double cavity moulds for the 9mm. # 356-120-TC and #356-125- 2R. Both drop at .357 to .3575 and when run through a .357 sizer work perfectly in a Walther P-38, Taurus PT 92 and a Springfield XD9. I have heard the 6 cavity moulds drop smaller boolits, around .356 to .3565....evidently not all .356 moulds are not equal. I guess thats why we tend to have more than one mould.
Gary

[Shiloh]

I have a LEE 125 gr RN. It is the only one which drops large enough to be useful. The other three drop to small.

Shiloh

[Cherokee]

I have two of the Lee 356120TC lube groove 6 cavity molds, both drop about .358 from 3/3/94 alloy. I size .356 for my 9's. I tried 357 and saw no difference, .358 gave tight chambering. YMMV

[mdi]

FWIW; Reloading manuals just tell you what components they used to get listed results (diameter, weight, charge, etc.). They are not defining the exact size that must be used. I own 2, 9mms, one slugs at .356" and one slugs at .358"...

[captaint]

I have a few 9mm molds. A Lee 356-120, drops right at .357. Too small. An RCBS drops at .357. They all leaded the barrel. Finally got an MP 358 hollow point. Now, that one drops them at .359. We size to .358 and that works. Recently got a NOE 135 Gr RNFP and it drops them at .359. Works great. I have the slug from my DW 9mm (1911). If memory serves, it's around .3568.
My .358 Star die produces boolits right at .3578. Close enough to prevent leading and gives good accuracy. The 9mm handguns are certainly individuals in what they like.

[paul edward]

After getting my first 9mm in 1972, I ordered dies, Lyman 356402 mold and a .356 sizer for my 310 tool. Loads with this bullet were not accurate and leaded the barrel. Gave up on casting for the 9mm. After joining this forum, I have since learned enough to make me want to try cast 9mm again.

[zomby woof]

I've owned a Witness for 15 years. It leaded like crazy with all the commercial 9mm boolits I bought. After joining this site and reading, my Witness needed .358 boolits and has a very long throat. I load my .358 boolits to 1.145" and no more leading.
My M&P Pro seems to like .356 and has a much shorter throat.