#### Scott Martin

##### SOC-13

Hello

I've been playing around with the FF&S small arms design sequence, and after crunching the numbers for a shotgun shell got a mass per round over 2 kg. Now admittedly this was a *big* shotgun, but the weight seemed a bit extreme to me, so I did some hunting and tracked down the mass (shipping weight) of some various 12 Ga shotgun rounds, and compared them to the weight of the same 12 Ga shotgun round according to FF&S (and the formula is *exactly* the same in FF&S-2):

Solid shotgun rounds for a 12 Ga:

B&P Big Game Ammunition 12 Gauge 2-3/4" 1-1/8 oz Rifled Slug Box of 10

Box of 10 2-3/4" rounds have a shipping weight of 0.9 lb

Pellet (#8 birdshot) rounds for a 12 Ga

Bismuth ECO Ammunition 12 Gauge 2-3/4" 3/4 oz of #8 Shot Box of 10

Box of 10 2-3/4" rounds have a shipping weight of 0.8 lb

00 Buckshot rounds for a 12 Ga:

Fiocchi Ammunition 12 Gauge 2-3/4" 00 Buckshot 9 Nickel Plated Pellets Box of 10

Box of 10 2-3/4" rounds have a shipping weight of 0.9 lb

According to FF&S, the wieght of a single 12Ga shell should be:

70x3.14159*18.5*18.5*0.003 G = 225g per round. Note that this assumes that the round is 70 mm long, not ~76 mm long

Actual weight is ~40g per round

So this seems to be out by a factor of about 6, fairly significant if this is true across other firearms as well.

Anyone out there have comments on what kind of densities I should be expecting in "real world" ammunition, so that I don't have to go hunting this down for other ammunition types? I'm pretty sure that there are folks out there who can give me the weight and dimensions for .45 APC ammo (for example) so I'll promise to do the calculations for what FF&S says the ammo should weigh, and compare to Real World ammo weights and see if there's a consistent error, or even just a trend across ammunition types. Just so we have a reasonable basis for comparison, FF&S uses the following ammo types:

Shotgun

Straight

Necked

FF&S assumes pistol ammunition is straight, so if it's necked pistol ammo I'll compare both ways to see if "straight" is a good assumption

What I need are the length and diameter of the ammunition, and the weight per round (including the brass / case / whatever)

<EDIT> Of course if you have slug weight, propellant weight and muzzle velocity, I suspect that I'll be doing some work on reverse engineering these as well... </EDIT>

Thanks

Scott Martin

I've been playing around with the FF&S small arms design sequence, and after crunching the numbers for a shotgun shell got a mass per round over 2 kg. Now admittedly this was a *big* shotgun, but the weight seemed a bit extreme to me, so I did some hunting and tracked down the mass (shipping weight) of some various 12 Ga shotgun rounds, and compared them to the weight of the same 12 Ga shotgun round according to FF&S (and the formula is *exactly* the same in FF&S-2):

Solid shotgun rounds for a 12 Ga:

B&P Big Game Ammunition 12 Gauge 2-3/4" 1-1/8 oz Rifled Slug Box of 10

Box of 10 2-3/4" rounds have a shipping weight of 0.9 lb

Pellet (#8 birdshot) rounds for a 12 Ga

Bismuth ECO Ammunition 12 Gauge 2-3/4" 3/4 oz of #8 Shot Box of 10

Box of 10 2-3/4" rounds have a shipping weight of 0.8 lb

00 Buckshot rounds for a 12 Ga:

Fiocchi Ammunition 12 Gauge 2-3/4" 00 Buckshot 9 Nickel Plated Pellets Box of 10

Box of 10 2-3/4" rounds have a shipping weight of 0.9 lb

According to FF&S, the wieght of a single 12Ga shell should be:

70x3.14159*18.5*18.5*0.003 G = 225g per round. Note that this assumes that the round is 70 mm long, not ~76 mm long

Actual weight is ~40g per round

So this seems to be out by a factor of about 6, fairly significant if this is true across other firearms as well.

Anyone out there have comments on what kind of densities I should be expecting in "real world" ammunition, so that I don't have to go hunting this down for other ammunition types? I'm pretty sure that there are folks out there who can give me the weight and dimensions for .45 APC ammo (for example) so I'll promise to do the calculations for what FF&S says the ammo should weigh, and compare to Real World ammo weights and see if there's a consistent error, or even just a trend across ammunition types. Just so we have a reasonable basis for comparison, FF&S uses the following ammo types:

Shotgun

Straight

Necked

FF&S assumes pistol ammunition is straight, so if it's necked pistol ammo I'll compare both ways to see if "straight" is a good assumption

What I need are the length and diameter of the ammunition, and the weight per round (including the brass / case / whatever)

<EDIT> Of course if you have slug weight, propellant weight and muzzle velocity, I suspect that I'll be doing some work on reverse engineering these as well... </EDIT>

Thanks

Scott Martin

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