How do they come up with bullet weights?

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Prof Young

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So, last time I was able to find 9mm bullets on line I settled on 147 gn plated round nose.

They load and shoot fine. I can find formulas for them in my load data books.

But how the heck does one decide to make bullets that weigh 147 gn. It just seems like an odd number . . . pun sort of intended.

Life is good?
Prof Young
 
Why do you think bullets should be an even number? There’s no logic to trying make bullets come out to a specific weight because the number is even, rounded up, or any other factor.
 
The 147gr 9mm standard is awfully close to the 158gr 38 special. You could load 158s in 9mm but powder volume is low and max velocity is too due to lower powder volume. 110 is a common bullet weight for 38/357 caliber compared with 115 for 9mm and 124/125 grain for both. 9mm bullets run about .355 but some are .354 and some may be .356. That's compared with 38 caliber at .357 or .358. For all practical purposes the bullet diameter and barrel dimensions for each "caliber" is basically the same depending on what a common barrel diameter or twist diameter is in a particular country or factory. What is more significant differences are features specific for each caliber such an a cannelure for revolver bullets vs no cannelure for auto pistol bullets and more rounded bullet noses for auto pistol vs. more blunt bullets for revolver/lever guns. I'm sure the different standard weights for each caliber are probably more to help distinguish bullets with the correct features rather than the correct weight and diameter. No reason you can't load 147s in a 38 but you may not have the correct crimp groove so roll crimp may not work with those bullets designed for 9mm.
 
I suspect it started with a bid request from some government agency. POSSIBLY, note I chose my word carefully so as not to be corrected. Possibly someone decided that the bullet needed to have certain ballistics, range, speed and/or penetration value. The math magicians did their thing and the projectile weight was the allowed variable. In order to make the mandated numbers work, the weight ended up odd value out...but who really knows. I like blaming it on a federal contract. We are always told to follow the money.
 
I have another theory.

What is the first thing that comes to mind...230. How about 158, or 147? 255?

I suspect many bullet weights are set to help prevent confusion between calibers. Not always, but a fair amount.
 
The 147 grain loading for 9mm is subsonic, intended for use with a suppressor. Probably the 147 grain weight was selected to give similar energy levels as the supersonic rounds, while also feeding reliably and meeting the maximum cartridge length.
 
To prevent caliber confusion I suggest folks might try to remember the 230 little bullets go in the little gun on your belt and the 405 big bullets go in the big long one in the truck. I hope this helps.
 
I suspect the engineering comes up with a standard form,but then the scales determine the weight.
Magazines,feed ramps,rifling twist,and the tradeoffs of aerodynamics ,and mass vs velocity from a given bore dia all factor into a bullet design.

But maybe,in the end,the toolmaker makes the dies,the dies make the bullets,the scale weighs the bullet,and they write the numbers down on the drawing.
 
I think at one time the goal was to achieve a particular weight. Today the emphasis is on achieving a particular shape to optimize performance. Bullet weight is secondary and whatever the weight ends up being is just what it is.

My experience is more with rifles, but the 165 gr bullet weight is pretty popular in 30 caliber rifles. But lately the emphasis has been on developing much more aerodynamic bullets. To achieve that goal many manufacturers are now offering 167 or 168 gr bullets. The weight is close enough to use the same powder charges, but the long range performance of the much more aerodynamic 167 and 168 gr bullets are enough better to justify a bit more weight.

Hornady has a 140 gr 6.5 bullet, but the 143 gr bullet has higher BC's. Several companies are now offering 155 gr 30 caliber bullets instead of 150's for the same reason.

The 147 gr 9mm bullets are pretty close to, if not the same length as 124 gr bullets. But with a flat point instead of a round nose to make them heavier. I'm guessing they were trying to get a heavier bullet in 9mm that was the same length as 124's and 147 gr is just where it fell.
 
I never designed bullets but designed a lot of other ITAR equipment. The engineering process is the same:
Define a requirement - caliber, min & max dimensions, purpose, cost, other factors (jacket, tracer, effectiveness meeting expected results, etc)
"Balance" all the requirements and decide on the best parameters windows.
Design prototypes, try, tweak, repeat until you get the formula right, the boss / customer stops, the project runs out of money, etc.
Start limited production, minor tweaks follow.

Viola! you have the perfect 147.3gr 9mm bullet. (till someone tweaks the requirements and you start over)
 
I believe Browning designed the 45ACP around 1900 with a 200 grain bullet at 900 to 950fps and the military said, WHHHHHHAAAAAAA, We want a heavier bullet in 1902 after shooting at cadavers and slabs of beef with rounds from 30 Luger to 45 Colt and watching them swing. Then Browning designed the slower 850fps 230 grain bullet around 1904 or 1905 and the military trial board said, "genius" but the gun needs some work. I have wondered over the years if they would have been better served with Browning's lighter original design! By 1910, the whole package came together and 230 became the "standard" ball loading for 45 Auto.
 
jmr40 said:
The 147 gr 9mm bullets are pretty close to, if not the same length as 124 gr bullets. But with a flat point instead of a round nose to make them heavier. I'm guessing they were trying to get a heavier bullet in 9mm that was the same length as 124's and 147 gr is just where it fell.
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Nope. 147 grain bullets FN are longer than 124 RN bullets.
 
In short, I suspect we have odd weights because we have kept somewhat traditional projectile designs/profiles and combined them with modern materials to make the bullets...

If I had to guess it all started with round ball.... Bullet weight was dictated by bore diameter.

After that minie ball, probably tried to keep similar weight as round ball to keep powder loads consistent and safe in the rifles

Going to traditional lead bullets, they kept the traditional proportions and filled in the skirt area

Going to modern bullet, they kept the same profiles/sizes as traditional lead so they would function in the current designs, but ended up with odd bullet weights due to the copper jackets reducing over all weight.
 
But how the heck does one decide to make bullets that weigh 147 gn.
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That's a 9.5 gram bullet. Most of the world uses the metric/SI system of grams, kilograms, meters, kilometers. It's not a strange weight, it's just a sensible step up from 7.5 gram/115 grain and 8 gram/124 grain 9mm bullets.
 
Scorch said:
That's a 9.5 gram bullet. Most of the world uses the metric/SI system of grams, kilograms, meters, kilometers. It's not a strange weight, it's just a sensible step up from 7.5 gram/115 grain and 8 gram/124 grain 9mm bullets.
Click to expand...
This makes sense. Then I’m guessing because our scales are calibrated in grains for accuracy in weighing powder the bullets were listed this way to avoid confusion and the need for conversion tables.
 
Scorch is right. It's the same reason 147-grain bullets are in 7.62 NATO ball ammo. Both cartridges are NATO, both throw that same bullet weight for some purposes. 10-gram bullets are 154.3 grains and that number is where (within max tolerances) the 155-grain .308 Palma bullet weight came from. 112-grain 9mm bullets are 7¼-gram bullets. 115s are within tolerances for 7½-gram bullets. 124-grains is within tolerances for an 8-gram bullet.

A logical progression would be whole numbers of grams, but either they had some specific criteria for each weight to meet or they got a medium to hold a seance and spoke to Thompson or LeGarde or whoever was ultimately responsible for changing Browning's 200-grain 45 Bullet to 230-grains.

Code: 
 Grams	   Grains
 1.00 g =  15.4 grn
 2.00 g =  30.9 grn
 3.00 g =  46.3 grn
 4.00 g =  61.7 grn
 5.00 g =  77.2 grn
 6.00 g =  92.6 grn
 7.00 g = 108.0 grn
 8.00 g = 123.5 grn
 9.00 g = 138.9 grn
10.00 g = 154.3 grn
11.00 g = 169.8 grn
12.00 g = 185.2 grn
13.00 g = 200.6 grn
14.00 g = 216.1 grn
15.00 g = 231.5 grn
 
As I understand it, the 230 gr .45 1911 was all they could get in the short case with good velocity at reasonable pressure; they would like to have had the 250 gr of the 1873 and 1909 revolvers.
 
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