Adjusted Minimum powder charge calculations for reduced OAL: 9x19 OAL 1.040"

T

TheGuyOfSouthamerica

Moderator
Adjusted Minimum powder charge calculations for reduced OAL: 9x19 OAL 1.040"

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I thought I would start a new thread with this question I have (I posted it here originally https://thefiringline.com/forums/showthread.php?t=584046)

Vitha Vhiouri states 4.4 grain minimum powder for VV N330 using an 124 grain LSWC (I assume this is some sort of Trucated Cone. Which I am using) in the 9 mm Luger for an OAL of 1.142".

My OAL is 1.040".

So I saw on another forum an calculation to adjust minimum powder weight for reduced OAL.
Like this:
4.4 grain VV N330 divided 1.142" OAL multiplied my own reduced OAL of 1.040" = New minimum powder charge for the reduced OAL (deep seated bullet).

4.4 / 1.142 * 1.040 = 4.00 grains of N330.

Is this calculation correct?

The Lee 0.5 powder measure dipper gives me (scraped of) 3.8 grain to 3.9 grain of powder by volumen. The Water weight of the powder space in the case is 6.3 grains.

What you guys have for experience with OAL deep seated lead bullets?
 
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If you are working with listed starting loads your way is likely as good as any.
If you are working with near maximum you will need to figure the internal volume with the bullet seated for both and multiply the charge by the ratio of the volumes.
V1 = larger volume
V2 = smaller volume
......................V2
large charge x ----- = smaller charge
......................V1

What we are doing here is interpolating a charge and it is not recommended as a safe way to determine a reliable powder charge.
 
ShootistPRS,

That is supposed to be the 9mm Luger starting load for 124 grain bullet with 4.4 grain VV N330 powder for an OAL of 1.142".

How do I determine the large volume and small Volumen? What is that referring to?
What do you referr to large Charge?
 
GuyOfSouthAmerica,
To get V1 mark a case at the book seating depth for the bullet and fill the case to that level - weigh that powder charge that is V1 the larger volume.
Get V2 by marking a case at the shorter seating depth and fill to that volume - weigh that charge - that is V2
Divide V2 by V1 (7/9 for example) to get the ratio (.778).
Multiply the recommended load by the ratio (5 x .778 = 3.89) to get your new powder charge (3.89)
The numbers above are just for an example and in no way real. You will have to make the measurements to get the actual numbers.
Remember that you are extrapolating a load and there is no guaranty that the pressures will be the same or even safe. Take appropriate precautions to protect yourself from injury.
 
There is no such thing as "Adjusted Minimum powder charge calculations". There is Max OAL and Minimum OAL. SAAMI Max for 9mm(that works extremely well for the 121 grain cast TC's(Truncated Cone) I've used for eons) is 1.169". Minimum is 1.000".
There's no need to fiddle with some internet calculation.
You really don't need to fiddle with case water capacities either.
 
An Lee lead cast 124 grain Truncated Cone bullet, 9mm Luger, will NOT chamber an 9mm Luger pistol unless seated to OAL 1.040".

Seated with more OAL than I have to foreward assist like in an AR15.

That is my experience.
 
Iv'e been loading my Truncated Cone bullets at 1.040 for years and never used a reduced load. Go down a little from max load and work it up.
 
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