Correct Size for 9 MM?

[plattincreek]

Greetings! I would like to hear your opinions on something. I am not new to casting but just picked up a new RCBS mold for 9 MM (115 grn. rn). In looking at both the Lyman Cast Bullet Manual as well as the regular Lyman Reloading Manual they both state that the 9 MM bullets should be sized to .358. Just off the top of my head that seems a little big. 9 MM slugs sized to .38 size? What diameter do you use for your 9 MM cast bullets? Any other tips for casting 9 mm? Thanks!

[MaryB]

I slugged my barrel and went .002 over that, came up at .358

[tazman]

The following link is the best information I know of for beginning to load a 9mm.

http://castboolits.gunloads.com/showthread.php?121607-Setting-up-for-boolits-in-a-new-9mm

[paul edward]

Slug the bore and start with a bullet .002" larger.

My initial results with cast bullets for the 9mm were not encouraging. I tried bullets from a Lyman 356402 mold, sized .356", in a P-35 Browning and a P-38 . That was in 1974, long before I had the resources offered by this community. Now that I understand the need for slightly oversize bullets, I have had good luck developing acceptable loads that do not lead barrels.

[tazman]

My barrel slugs at .3553. i use either .357 or .358 depending on how the boolits drop from my mold.
I tried .356 but the results were very poor.

[bcp477]

The PROPER, specified groove diameter for the 9mm Luger is 0.355". Thus, the theoretical proper diameter for jacketed pills would be 0.355".......and for cast 0.356" or larger, depending on what works best for a particular barrel.

HOWEVER, the unfortunate truth is that ACTUAL groove diameters on 9mm's tend to be all over the place, depending on manufacturer, etc. So, many such barrels will need larger than normal pills in order to work well without leading. I've even heard of some such guns needing 0.360" boolits.

I've been lucky over the years, in this regard, myself. None of the 9mm's I've had have been much oversized, if any at all. Currently, I have a Kahr, which is actually undersized (close to 0.354")...... a Sig (spot on at 0.355")......and a Bersa (polygonal rifling, but close to 0.355", as near as I can tell). All shoot 0.356" diameter boolits well (even the polygonal Bersa).

Your mileage, as they say, may vary. That is why it is doubly important that you SLUG YOUR BARREL. Then, you will know what you have to work with. It will potentially save many hours of frustration, not to mention wasted projectiles.

[trapper9260]

I size my to 356 and no problems and good to go but do like bcp477 stated slug your gun and it will tell you what you will need to use.not all guns are the same. What works in one gun dose not mean will work in another.

[bedbugbilly]

I cast the Lee 356-120-TC - they drop at .358 - .359 from my mold - run them through a Lee .357 sizer - TL in alox & paste wax. I've had no leading at all in my Ruger SR9. YMMV with your pistol depending on your pistol's actual bore size. If you have the sizers - you could try .358 and .357 and see which works best for you.

[captaint]

Success, for most folks, seems to be .357 or .358 for the 9's.. Myself included. I initially tried sizing to .357 and got some leading. Going to .358 eliminated that, so I'm happy.
Might want to read the sticky in "Pistols....Handcannons section" by MtGun44. Excellent reading for a 9mm loading beginner. Excellent. Mike

[Hardcast416taylor]

I went .358" quite a few years back and have never had a problem.Robert

[lotech]

Load the 9mm with the largest bullet (usually .357" to .359") that will freely chamber in your gun.

[DLCTEX]

I have been sizing to .357 and it has worked well in 4 guns so far. All four are S&W.

[JonB_in_Glencoe]

I size to .357

I have had several 9mm guns over my casting career, the larger one slugged at .357 and shortly after I got that gun is when I started sizing to .357 I had no problem with that gun or chambering in the 'tighter' guns. I imagine .358 will work also. The next worry is to get proper expanding of the case...I was using the Lee powder thru expander die with 'stock' insert and it wouldn't expand the case enough and cause it to swage the boolit smaller when seated. I had a custom insert made for 9mm as well as 40. The 40 was just as bad.
Good Luck,
Jon

[plattincreek]

Thank you for your advice, it is much appreciated. I understand slugging the barrel, that part is no problem, but my micrometers just don't have fine enough jaws to actually get into and measure the groove diameter. I will see if I can find a better micrometer. Thanks again.

[tazman]

Thank you for your advice, it is much appreciated. I understand slugging the barrel, that part is no problem, but my micrometers just don't have fine enough jaws to actually get into and measure the groove diameter. I will see if I can find a better micrometer. Thanks again.

The groove diameter is measured on the outside surface of the slug from the barrel. If you try to measure inside the grooves on the slug you will be measuring the bore diameter. If you look into the barrel of your firearm, the bore is the dimension at the inside of the lands. The groove diameter is the dimension of the bottom of the grooves between the lands.
If you already knew this I apologize. It sounded as if you were confused.

[Echo]

load the 9mm with the largest bullet (usually .357" to .359") that will freely chamber in your gun.
a big +1...

[Hickok]

.358" in my Beretta 92FS.

[plattincreek]

tazman, thanks, I was getting it backwards.

[Larry Gibson]

I sized 9mm bullets at .356 for years and had no problems with leading (always used Javelina or similar NRA 50/50 lube). I used that size in many, many different 9mm handguns of commercial and military make. Then I ran into a couple subguns in the early '90s that ran .357 so I sized at .357 for them and just started sizing all my 9mm cast at .357. That size shoots quite well in every 9mm I've shot them in, handgun or subgun.

Larry Gibson

[Ed_Shot]

I was sizing .357 for 9MM and I got tired of changing the sizing die in my Lyman 450 between .357 and .358 to load for 38/357's. Found that .358 works perfect in the 6 different 9MM's and 4 different .380's I load for in my family. I've never slugged a barrel yet. If I was having a problem with accuracy or leading I'd do something different.

[fatelk]

I wonder why 9mm bore diameters vary so much? I have a couple old Hi-Powers that both slug .358, and a little Taurus .380 that also slugs .358". My molds throw .358" so that's what I use, and it works pretty well.

[Larry Gibson]

My guess is they very more because of inaccurate cheap calipers than any other reason. I have checked numerous of them against certified pins and some are off by several thousandths in the .300 - .400 range.

On should never depend on one slug for measurement (I prefer a minimum of 3) and a good micrometer should be used for the measurement.

Larry Gibson

[fatelk]

In the instance of my pistols: I measure with a micrometer, not a caliper. I do know how to use a caliper correctly as well, but I'm sure some don't.

As to slugging, I got smart and remembered the ingot of cerrosafe I had in my toolbox. It worked really well and measured the same as the slug (after 1 hour).

I'm actually pretty happy with the load I just got worked up. No leading and acceptable accuracy. That's been a first for me in 9mm.

[MtGun44]

The only problem with "too big" is the possibility of difficulty chambering, which happens
FAR less commonly than problems from "too small". Build up a dummy round with a .357 or
.358 (or both) boolit seated and see if it passes the drop test in a dismounted barrel. If
it does, you are good to go.

Again - "too big" works much better than "too small" - and boolits work best .001 to .002 over the
groove diameter in most guns.

Bill

[MtGun44]

For whatever reason, it seems that 9mms have about the greatest variation
in groove diameter of any cartridge that I have ever run into, and they do
not seem to be running on the tight side - either on the old 'normal' of .355-.356
or out in the .357-.358 range. Actually the tightest I have ever even heard
of has been older Colt .38s with .354 groove diam in some.

+1 on many calipers being off a few thousandths. Also, many folks are not skilled
in the use of these devices, especially on a very soft slug that an be deformed
with a bit too much pressure.

Bill

[Shiloh]

For me, it is .358

Shiloh

[plainsman456]

I save the 356 sizer for the 380 and use the 357 for the 9mm.

Works well in many so far.

[dale2242]

I use NRA 50/50 lube.
After much trial and error with size and alloy, I size to .358 and use a fairly hard alloy to prevent leading in my Taurus 9MM.....dale

[gwpercle]

I size em .357. The only reason is, I have a .357 sizer die, I started loading for a 357 magnum and the Lyman #3 book said to size them .357...so I did. When I got a 9mm (Walther P-38) I just used the Lyman #358345 mould I had for the 357 mag. to cast 115 gr. SWC's to use in the 9mm, sized to .357 because that's what I had and they work just fine in the P-38 and a Taurus 92.
Try whatever size you have and see if your gun likes it.
Gary

[sigep1764]

I size to 358 for all three of my 9mm pistols. And they all get fed one load. Lubed with Lyman Alox NRA formula, no leading.