OAL for 9mm cast bullet


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jdgreen
November 25, 2012, 06:05 PM
I picked up some S&S 125 gr. cast bullets and some 9mm Luger dies at a gun show and loaded some up. The one on the left is loaded at 1.125, which is what I have listed for minimum OAL. I thought it looked at bit strange, so I seated the bullet down a bit more to 1.090 and applied a slight roll crimp. I test fired 30 of each and they performed similarly with no problems. The only other cast bullets I load are for revolvers, so I'm not as concerned with their OAL. Any insight or recommendations?

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rcmodel
November 25, 2012, 06:11 PM
The long one looks almost right.
The other one with the driiving band inside the case is too short.

Seat so you have about a thumbnail width of the bullets front driving band sticking out of the case mouth.

Then, Taper-Crimp to .376" - .377" when measured at the case mouth.

Never Roll-Crimp for any straight wall auto pistol cartridge, as they all must headspace on the straight edge of the case mouth.

rc

918v
November 25, 2012, 06:12 PM
The 1.090" roll crimped is incorrectly loaded. That little bit of bullet shank needs to stick out past the case mouth to align the bullet in the freebore with the bore centerline. The way you have the short one loaded, the bullet has to hop and skip into the bore. Plus, you should not be roll crimping the case anyway because you need it to headspace on the case mouth.

RE-15
November 25, 2012, 09:16 PM
Will the first bullet chamber correctly? 1.09 is what I am at with MO bullet, but it has a different profile.

4895
November 25, 2012, 09:54 PM
In my experience, the shorter one where you seated passed the driving band will lead the barrel horribly.

I would follow RC's advice as his experience has taught all of us well.

jdgreen
November 25, 2012, 11:47 PM
These chambered fine, but I did have some barrel leading. I reloaded another batch per rcmodel's and 918v's recommendations. Will have to wait a day or two to shoot them. I'll post results. Thanks all.

1KPerDay
November 26, 2012, 01:03 PM
1.09 is what I am at with MO bullet, but it has a different profile. Same here... the MBC smallball needs to be 1.09" or slightly less to pass the plunk test in my pistols.

To the OP, depends on WHICH cast bullet. ;)

Quoheleth
November 26, 2012, 10:53 PM
FWIW, in my CZ85, MBC's Smallball needs to be between 1.075" and 1.08" to fit my chamber. Anything longer than that and it'll hang up.

To that end, I also use data for the shorter size loading from Lyman's pistol manual.

Q

coalman
November 27, 2012, 01:14 AM
I load just before the driving band ends, not past it. Whatever that OAL for that bullet type is what I use if it fits in my chamber.

jdgreen
November 28, 2012, 09:23 PM
**UPDATE**
I loaded some more similar to the cartridge on the left (above). They had an OAL of 1.135. I am using a S&S cast 125 gr RN .356. My calipers have them at .357. I slugged the barrel and got .357, if I did it right. Here is a picture of the breech end of the barrel. This is after 30 rounds. It looks a little worse than it did the first 30 rounds originally. What do you think is happening here?

4895
November 28, 2012, 10:04 PM
Theory #1:

If the barrel is slugged at .357", you may need a .358" bullet to properly obturate.


Theory #2:

Too much crimp.

If you are using a crimp die in a separate step, try removing that operation from the equation.

Load a dummy round (no powder/primer).

Set the oal where you think it is right, i.e. 1.125 1.135 etc.

Without running it through a crimp step, try the plunk test and drop the round in the barrel chamber and see if it seats fully or hangs up. If it hangs up, apply only the slightest amount of crimp and try again. Repeat as necessary until the round drops easily into the barrel. I add just a hair more (crimp) adjustment to the crimp die to ensure even crimping with brass that may differ in oal.

A 9mm doesn't require a crimp so much as a "de-flare" to removed the belling created before seating the bullet. A friend of mine only flares the case barely enough to start the bullet and doesn't even use a crimp die.

If the crimp is excessive, it could be swaging the lead into a smaller diameter allowing propellant gases to escape beyond the bullet melting lead in the barrel at the throat until it reaches a point of obturation. I am not an expert by any means but I kinda sorta understand obturation. It is what happens when the lead bullet is slightly larger than the bore diameter and the propellant gases cut into the lead at just the right pressure to allow proper bullet to bore seal. If the pressure is too great, or the bullet too small (possibly from over crimping that would squeeze the bullet smaller) the hot gases go beyond the bullet base and deposit lead into the throat of the barrel.

jdgreen
November 28, 2012, 11:15 PM
Yeah, I wondered about the bullet diameter. The cartridge on the left in the first picture shows the case is bulging a bit. Does that indicate the bullet is getting swaged down some amount? If I used a cast .358, would it get swaged in a similar fashion? Can anyone recommend a cast bullet? I wanted to try some cast bullets in hopes of casting my own 9mm (I already cast for .38 special).

For that last batch I crimped as little as possible - only enough to unflare the case. I put an empty FL sized case through the crimp die. The die didn't seem to touch it, so I'm not crimping beyond the normal taper of the case.

chris in va
November 29, 2012, 01:37 AM
Are those bullets lubed?

Anyway, I use a Lee 356-125-2r mold to good effect in my CZ. It drops at 360, so size to 358. Previously I was using a 358-125-rf but got tired of having to load it at 1.02 before it would chamber.

RhinoDefense
November 29, 2012, 01:47 AM
Your alloy is too hard, your pressure isn't high enough for obturation, or your bullet isn't sized properly. What you are seeing is leading from blow-by. The bullet is not obturating and leading occurs.

918v
November 30, 2012, 11:55 AM
Your bullet is too small to seal the freebore. Gas is leaking around the bullet and leading up your bore.

I recommend Missouri Bullet 125gr Cowboy #2. It is made out a softer alloy that will obturate at any 9mm pressure and sized at .358" so it will fit your freebore well. It is blatantly obvious your freebore is larger in diameter than your groove diameter. You need the bullet to fit that dimension.

I load the Cowboy #2 to 1.040" OAL which makes the case mouth cover the crimp groove. I have loaded them as light as 3.2-3.8grs of Bullseye in my G17, but they also shoot well with 3.8-4.1grs of 231.

No leading. Ever! Listen to me. I've been doing this for a while.

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