Author Topic: Popular 9mm Bullet Lengths  (Read 41636 times)

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Offline romukom

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Re: 9mm Bullet Lengths
« Reply #75 on: July 14, 2017, 06:58:35 PM »
Adding into the list:
RMR 124 gn Plated Round Nose Flat Point (RNFP) : 0.527"

RMR 124 gn New-in-house FMJ Flat Nose (FMJ-FN): 0.552"

Offline RSNO

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Re: Popular 9mm Bullet Lengths
« Reply #76 on: February 07, 2019, 02:18:09 AM »
Gentlemen, here?s a set of ?equivalent? lengths for Rainier Plated HP.

115 gr HP, 0.515
124 gr HP, 0.547

Rationale and methodology: The Rainier HP bullets have concave bottoms. Physical length isn?t meaningful because there is a concave volume down there. For the purpose of figuring out bullet seating depth, the length of an equivalent flat bottom bullet is good enough to calculate the remaining case volume.

You can check my math.

1.   Average of 5 bullets is 115.0 gr. The length is 0.525, BUT the bottom is concave.
2.   I sanded off the concave bottom of a 115 gr Rainier HP. The bottom is now flat. The bullet weigh in at 111.7 gr and 0.503 long.
3.   That means the removed lead from the concave bottom is 3.3 gr.
4.   Question: We want to add that same volume of lead back to the bottom of the bullet in the form of a 0.355 diameter disk. What would that length be?
5.   1 gm = 15.4 gr.              So 3.3 grain = 0.214 gm
6.   Lead has a density of 11.34 gm/cm3.   So  0.214 gm =>0.0189 cm3.     
7.   1 in3 =16.39 cm3.          So 0.0189 cm3 => 0.001153 in3
8.   The area of a 0.355 disk (added to the bottom of the bullet) is 0.0989 in2. 0.001153 in3 would fit in 0.0117 in length.
9.   Add that 0.0117 to the 0.503 from the shortened 111.7 gr gives 0.5147. round off to 0.515.


Do the same thing for the 124 gr bullet. You need to shave off 12.3 grain. That extra length comes out to 0.0436. Add that to 0.503, we get 0.547.


Offline Wobbly

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Re: Popular 9mm Bullet Lengths
« Reply #77 on: April 16, 2020, 10:03:01 AM »
Missouri Bullet Co  (MBC)
135gr  "IDP#8"  0.622"  Coated lead RN


Post #1 was re-formatted as a "list" for easier editing and searching on 4/17/2020
« Last Edit: April 17, 2020, 08:58:24 AM by Wobbly »
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Offline recoilguy

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Re: Popular 9mm Bullet Lengths
« Reply #78 on: April 16, 2020, 10:55:14 AM »
forgot about this thread.
I like this one....great info
What I lack in speed , I make up for with inaccuracy

Offline recoilguy

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Re: Popular 9mm Bullet Lengths
« Reply #79 on: May 08, 2020, 08:23:06 PM »
I just bought some 124g round nose projectiles from Bayou Bullets. They have change the profile of their bullet considerably, their new bullet is much shorter and has no grease ring in it and I measured it today at .572. I don’t know if anybody looks at this thread anymore but I thought I’d put it in there

RCG
What I lack in speed , I make up for with inaccuracy

Offline Wobbly

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Re: Popular 9mm Bullet Lengths
« Reply #80 on: May 09, 2020, 10:15:36 AM »
List edited today. Thanks !
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Offline Duke Nukem

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Re: Popular 9mm Bullet Lengths
« Reply #81 on: May 19, 2020, 01:39:38 PM »
Armscor 124 grain round nose fmj measures an average of .594

I got an order of Missouri Bullet Co. 124 grain "small ball" round nose coated bullets yesterday, a sample of 25 ranged from .590 to .601, for an average length of .595 (this one is already listed, but my sample does not agree with what is on list). 

These also varied in weight from 122.5 up to 126.6, fwiw.

 

anything