Why does one 9mm bullet plunk and the other sticks

rwsmith

rwsmith

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Here's a picture of two 9mm cartridges, reloaded in 2 different batches one day after the other.

The bullets are both Missouri Bullets 125 gr. SWC, both measure .356" dia.

The diameter of the case at the mouth is:

.3775" (red bullet) and .3775" (gold bullet)

The case length (best I can measure an assembled cartridge) is:

0.7430" (red bullet) and 0.7440" (gold bullet)

OK, given that info, both of the cartridges plunk well in my Shield barrel. If I press on the gold bullet cartridge, it bottoms out hard on the rim in the chamber and drops back out when inverted with a little shake. The red bullet cartridge however plunks well, but sticks a little and if I press on it it feels like it's engaging the rifling (a soft lead feeling) and then I have a lot of difficulty getting it out with my finger nails and I have to wiggle the cartridge to get it out of the chamber.

I've had this problem forever and have improved my technique to where I get consistent ammo that plunks reliably, but this problem is only on SOME rounds.

Can anybody enlighten me?

I just had an idea. I'm going to plunk a sample of bullets and measure the depth plunking by the cartridge weight alone, then press the bullets in to see if and how many aren't bottoming out hard metal on metal.
 

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"Plunk" or close to it is fine, but it's not necessary that they "plunk". What's more important than "plunk" is that they feed and chamber flawlessly 100% of the time.
 
I never had any issues of this kind until I set out to load for an auto.
Ammo was hit or miss at first, often failing the plunk
Then it dawned on me that the taper crimp action acts like a brake, stopping the motion of the bullet you're still trying to seat.
So, I adjusted for no crimp and seat to desired depth, then readjusted for the crimp, with the seating stem removed.
The results were perfect
 
Hi Tek...

-BTM- said:
What’s the red coating?
Click to expand...

They are Hi Tek coated bullets from Missouri Bullets. They are clean and you can push the velocity in pistol into the over 2000 fps. range. I understand they work in rifles, too, but I think the limit is somewhere around 2400 fps, but don't quote me on that. You load them just like hard cast, or even gas-checked hard cast up to a point. And, they're PURTY. I don't specify the color but I alway end up with dark red but when I broke open the new (old) box for the next batch they were gold.

The cost is around 55 bucks/500. Economical in my book. And I've never had a problem with them. And I have shot MANY thousands of them of different calibers and styles.

Oh, PS: I use Missouri's 95 grain .380 in what I call 9mm Screamers. A hot load gets over 1700 fps out of my Ruger carbine.
 
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I think this...

venomballistics said:
I never had any issues of this kind until I set out to load for an auto.
Ammo was hit or miss at first, often failing the plunk
Then it dawned on me that the taper crimp action acts like a brake, stopping the motion of the bullet you're still trying to seat.
So, I adjusted for no crimp and seat to desired depth, then readjusted for the crimp, with the seating stem removed.
The results were perfect
Click to expand...

..is what I should do. Ideally, the cartridge should stop in the chamber when the cartridge mouth headspaces on the rim of the chamber. I need to sit there with a barrel and adjust the crimp until it plunks reliably and stops.

And probably if I pick up a different barrel, the rounds either won't plunk or will get stuck!::):D

And yeah, I've been reloading 9mm for about 10 years and it's the only cartridge that I've been unable to debug.:confused:
 
I think it's because...

-BTM- said:
Could just be the picture angle, but the shoulder on the red bullet looks to be extending farther out.
Click to expand...

The case is a little shorter and OOPs, I forgot to put in the overall length, but the red one is 4/1000 longer than the gold one:

1.082" (gold) and 1.086" (red)

In my thinking, that shouldn't make a difference because if it were a round nose bullet there would still be some bullet wall at the mouth of the case. unless you seat the ojive of the bullet below the case mouth like some 'smallball' bullets I've used that you have a short COL, something like 1.06" or they WILL give chambering problems. I don't have a problem with seating them a tad deeper if that is a problem, but I'll have to determine if it is a seating depth problem or a crimping problem.
 
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rwsmith said:
The case is a little shorter and OOPs, I forgot to put in the overall length, but the red one is 4/1000 longer than the gold one:

1.082" (gold) and 1.086" (red)

In my thinking, that shouldn't make a difference because if it were a round nose bullet there would still be some bullet wall at the mouth of the case. unless you seat the ojive of the bullet below the case mouth like some 'smallball' bullets I've used that you have a short COL, something like 1.06" or they WILL give chambering problems. I don't have a problem with seating them a tad deeper if that is a problem, but I'll have to determine if it is a seating depth problem or a crimping problem.
Click to expand...

It would seem to be one or the other. I would try crimping as a separate step as outlined above. Then run some others with oal exact. Ten or twenty of each should be enough.
 
Thinking is good. On the other hand, over-thinking...

They are cast, coated bullets; to find two in 500 that have IDENTICAL dimensions would be a miracle. There is no reason why two loads SHOULD be identical. Do they both work? That's enough to know.
 
I have pistols from Beretta, Glock, S&W and Walther in 9x19. The Walthers have the tightest chambers and shortest leades, so they get used for the plunk test. I've used (and like!) those Missouri Bullets SWCs, and there's hardly any shoulder sticking out of the case because of the Walther barrels. They run fine in my other guns too.

Note that those SWCs and current "no lube groove" RNLs require shorter-than-usual overall lengths, like ~1.05-1.06". That means there's more bullet inside the case, which means you may have to reduce the powder charge to keep pressures safe. I've gone from 5.6 grains of BE-86 for 124-grain FMJs at 1.14" to 5.1 grains with the NLG RNLs I'm loading now. Keep the chronographed velocities - from your gun, not a loading manual - about the same and you should be good.
 
Without looking at your loaded ammo, we are all just guessing. My guess is that your plunk problem is not the bullets you are using, but the brass.

If you want to find your contact areas, get out the magic marker. My opinion is that the bullets are identical enough that they are not the factor in this equation that causing your concern.

Now brass from different manufacturers, There’s some real variation! Start looking at headstamps. Some brass is a lot thicker than others. You want variation? Start weighing brass.

*I am being nit picky here. It’s your AMMO that is failing your plunk test. Non shooters call loaded ammo “bullets”. Reloaders separate the 2 terms for clarity.
 
Too much of the bullet's top driving band is sticking out .

You want the thickness of your thumb-nail sticking above the cartridge mouth ... no more .

Seat the bullets just a little deeper .

Cast bullets in the 9mm Luger are the most difficult to get all the "bugs" worked out ... The 9mm Luger is a cast bullet ... Stinker and I hate loading them ... buttt , once you get all the freaking bugs worked out ... they are Okay !

I don't care what all them book numbers say ... the problem is you are loading cast lead SWC's and you have too much bullet sticking out , Top driving band ... the thickness of your thumb-nail , no more ... Trust me on this one !
Keep On Keeping On and Load Safe ,
Gary
 
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Not sure if this technique has been covered here but you can use a unsized 9mm shell with a bullet started in it. Press the shell into the barrel chamber until it head spaces against the chamber mouth. Remove the cartridge and check the OAL. Reduce this by .001-.0015" and you should be golden.
 
One post mentions brass. 9mm brass seems to have the widest dimensional variations (thickness, case head dimensions) of all the handgun cartridges. Long ago I found that using a .38 Super or 9mm/.38 Super shell holder necessary. There may be something there, but I don't think so.

OTOH, you're using a SWC bullet with a shoulder, that isn't typical for the 9 mm and the chamber leade isn't cut for it. Back in the last century, recutting the leade (wadcutter throat) was part of adapting a 1911 to reliably work with an assortment of SWC ammo.

Based on experience with 1911s & SWCs, you've got too much shoulder out of the case. However, if they function, and an unfired chambered round extracts, I wouldn't worry too much about it, one color coating might be a hair thicker than the other. Might want to check your seating die for gunk buildup.
 
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This is very interesting as I am experiencing a similar issue with my 9mm loads. Just loaded 500 rounds and, using an EGW Major gauge, about two dozen were sticking in the gauge. All measurements were similar to the un-sticking rounds. According to my loading manuals, OAL=1.125” . Seems long. What was very curious was some longer rounds (1.130”) did not stick while some shorter rounds (1.120”) did stick. Head scratcher…….
 
OP how did you determine your OAL? Did you just go with whats in a manual or did you measure it like Tazz666 mentioned?
 
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