"Unit of Fire" Modern Day equivalent

[The Alaskan]

Not sure if this going to be an acceptable topic of discussion, but here goes.

I'm reading With The Old Breed by E.B Sledge in preparation to teach the War in The Pacific next semester, and on page 88, Sledge mentions a "unit of fire" and discusses the meaning in a footnote: "Determined from experience, a unit of fire was the amount of ammunition that would last, on average, for one day of heavy fighting. A unit of fire for the M1 rifle was 100 rounds; for the carbine, 45 rounds; for the 45 caliber pistol, 14 rounds..."

This is the first I have ever heard of this concept, and I wonder if there is a modern day equivalent. 100 rounds seems low to me. In my day, the standard load out was 210 rounds (M16 using the old ALICE gear), but, as I have been blessed with not ever having to actually be deployed, I don't know how long that was intended to last.

Can anyone speak to how many rounds our guys burn through in a day these days, just to have a comparison?

 

[mdauben]

I think that was just their version of the modern combat load. You have to remember that the Garand and M1 Carbine were both semi automatic weapons, as opposed to the selective fire M16. The .30 cal rounds for the Garand were also both heavier and bulkier than those of the 5.56mm. It might also be argued that even during WWII the Marines considered themselves marksman so perhaps they were more frugal (and more effective?) with their ammo?

 

[Driftertank]

I've heard the phrase "unit of fire," but only when used to describe logistics of artillery resupply. An artillery battery was cut off on a hilltop, and the only means of resupply was by helicopter. Given the load and range limitations of the helicopters available, it took a couple days of flight ops to deliver one unit of fire...and the battery, in hard contact with ground forces, was burning through their ammunition as quickly as it was brought in.

My understanding is that, while Logistics tries to be liberal in it's definition of a unit of fire, once rounds start going downrange logistical estimates always seem inadequate...

 

[AlexanderA]

I'm reading With The Old Breed by E.B Sledge in preparation to teach the War in The Pacific next semester, and on page 88, Sledge mentions a "unit of fire" and discusses the meaning in a footnote: "Determined from experience, a unit of fire was the amount of ammunition that would last, on average, for one day of heavy fighting. A unit of fire for the M1 rifle was 100 rounds; for the carbine, 45 rounds; for the 45 caliber pistol, 14 rounds..."

I think there is some confusion here. These round counts have to refer to the ammunition that was routinely carried: The 10 pockets of the Garand cartridge belt would be 80 rounds, plus 8 in the gun = 88 rounds. But the same cartridge belt used with the Springfield rifle would carry 100 rounds (two 5-round clips per pocket). (And the Marines used Springfields early in the war.) For the carbine, the 45 rounds would be three 15-round magazines -- two in the belt pouch plus one in the gun. Now, for the pistol, he's counting two magazines, presumably carried in the belt pouch with the gun empty. A strange methodology indeed.

In "heavy fighting," the troops would use more than this, relying on bandoleers or resupply.

I would simply disregard that passage in the book. I think the author just made up those numbers.

 

[JohnBiltz]

I've read the book and Sledge was not on Guadalcanal and was a mortar man in any event. But by the time he was in the war the M1 was the rifle.

Basic load was 7 magazines for the M16, 600 rounds for the SAW, 800 rounds for the machine gun and I can't remember what the count was for the 203. In a light Infantry unit the company would keep a complete basic load on its vehicle. After that it would have to be pushed down from Bn. Different units have different ways to keep up with ammo and do ammo replenishment.

 

[USAF_Vet]

"Determined from experience, a unit of fire was the amount of ammunition that would last, on average, for one day of heavy fighting. A unit of fire for the M1 rifle was 100 rounds; for the carbine, 45 rounds; for the 45 caliber pistol, 14 rounds..."

Based on what I've heard from vets, 100 rounds for an M1 wouldn't last one hour of heavy fighting, let alone one day of it.

Basic load was 7 magazines for the M16, 600 rounds for the SAW, 800 rounds for the machine gun

This is correct based on what I carried, although sometimes we carried more, but never less. Anyone who had a pistol carried 45 rounds, 1 mag in the gun, 2 spare mags.

The one pretty major firefight I had, personally I burned up most of what I was carrying, and that lasted about 10 minutes. Never even used the happy switch on the M4, either. All rounds were fired in semi auto.

 

[The Alaskan]

Thanks for your input and thoughts. I expect to field a few questions on this from my class when the time comes.

I thought 100 rounds per day of combat was incredibly low, but I thought perhaps, in those days, with guns that only fired semi and held less ammo, and ammo that was larger and heavier, a smaller expenditure of ammo might be normal.

I knew that it wasn't related to the 10 pocket waist belt carrying 80 rounds because virtually every photo I've ever seen of riflemen in WWII, in both theaters, showed the men carrying bandoliers, so I didn't think it was connected to how much ammo they carried. (Incidentally, wearing two bandoliers is HEAVY, it feels like having an extra rucksack on.)

USAF_Vet, 7 mags sounds like what I carried back in the 90's. Have you ever heard anyone talk about how long that is expected to last? Seems to me (and all my experience is training only) even that would run out quick, especially doing a Final Protective Fire.

 

[1911 guy]

Final Protective Fire? Do I sense another SeaBee?

Same as you guys, our load was 210 rounds for the M16 and 3 mags for the pistol. Either 45 or 21 rounds, depending on what the armory coughed up. I actually got handed a .38 revolver for a shipboard watch one time. Navy isn't always fielding the latest equipment.

I'm not aware of any official word on how long the fighting load is supposed to last. I do know that an awful lot of us carried bandoliers in our rucks to reload mags.

 

[lysanderxiii]

Determined from experience, a unit of fire was the amount of ammunition that would last, on average, for one day of heavy fighting. A unit of fire for the M1 rifle was 100 rounds; for the carbine, 45 rounds; for the 45 caliber pistol, 14 rounds..."

Some days, you don't even shoot a single round. And, some troops, like mortarmen or red-legs rarely shoot their rifles.

It was a logistical number used to estimate the total amount of ammunition that was needed to be shipped in. It has nothing to do with actual ammunition expenditure per engagement, or how much the average infantry man needs to carry.

From FM 9-6 "Ammunition Supply" definitions:

unit of fire - A unit of measure for ammunition supply within a theater from a tactical point of view, based upon experience in the theater. It represents a specified number of rounds per weapon, which varies with the types and calibers of the weapons. The unit of fire is not synonymous with the term "day of supply".... In general, it represents a balanced expenditure by the various weapons under conditions of normal action. The unit of fire prescribed by the War Department may be modified by theater commanders as necessary for each individual theater.*

__________________________
* A "day of supply" is the "estimated average expenditure of various items of supply per day in campaign, expressed in quantities of specific items or in pounds per man per day. A day of supply for ammunition is expressed in rounds per weapon per day."
__________________________

The "unit of supply" also makes ordering ammunition easier at the company and battalion level. The Company gets on the phone and tells Battalion S-4 "I need 60 units of fire for M1, 10 units of fire for BAR, and 6 units of fire for Carbine."

Now, supply knows that he wants 6000 round in M1 clips, 7500 rounds in M1903 stripper clips or boxed, and 3600 rounds of carbine ammo.

Or, the Company could just request a "unit of fire" for a company, and he would get a pre-calculated, (sometimes pre-packaged) load of ammo with a unit of fire for each weapon assigned to a typical infantry company TO&E.

The unit of fire for the army was slightly different than the USMC, for the Army this is the listed Units of Fire:

.30 cal Ammunition
per Inf Div - 1,783,200 / 2,446,900

per Arm Div - 4,813,080 / 10,049,500

.30 Rifle, M1 - unit of fire - 150 / day of supply - 5

.30 Automatic Rifle, M1918, BAR - unit of fire - 750 / day of supply - 45

.30 Light Machine Gun, M1919 - unit of fire - 2000 / day of supply - 150

.30 Heavy Machine Gun, M1917 - unit of fire - 3000 / day of supply - 150


.45 cal
per Inf Div - 26,002 / 68,232

per Arm Div - 580,420 / 1,727,040

Pistol - unit of fire - 7 / day of supply - 0.4

Submachine gun - unit of fire - 200 / day of supply - 20


.50 cal Heavy Machine Gun Ammunition

per Inf Div - 127,800 / 426,000

per Arm Div - 203,720 / 1,986,000

Ground - unit of fire - 900 / day of supply - 100

Antiaircraft - unit of fire - 1200 / day of supply - 90


60mm mortar

Unit of fire - unit of fire - 100 / day of supply - 7.5

per Inf Div - 8,100 / 18,225

per Arm Div - 11,400 / 12,825


81mm mortar

unit of fire - 100 / day of supply - 5

per Inf Div - 5,700 / 8,550

per Arm Div - 3,402 / 4,050


37mm gun

unit of fire - 100 / day of supply - 10

per Inf Div - 10,900 / 32,700

per Arm Div - 40,397 / 129,300


75mm gun

per Arm Div - 11,600 / 69,600


75mm howitzer

unit of fire - 300 / day of supply - 40

per Inf Div - 5,400 / 21,600

per Arm Div - 12,600 / 50,400


90mm gun

unit of fire - 125 / day of supply - 10


105mm howitzer

unit of fire - 225 / day of supply - 30

per Inf Div - 9,420 / 37,800

per Arm Div - 12,150 / 48,600


155mm howitzer

unit of fire - 150 / day of supply - 20

per Inf Div - 1,800 / 7,200
__________________________________________________

 

[JohnBiltz]

For those thinking 100 rounds of M1 as not being enough, M1s were 30:06. Those 100 rounds weighed more than 210 rounds of 5.56. Its not just about how many bullets you think you need, having to carry that ammo figures into basic load as well. When loads on soldier's backs are over one hundred pounds weight of ammo becomes important.

I did twenty years and never heard the term unit of fire. Terms of Art change over the years.

 

[lysanderxiii]

Even in WW2, 100 was considered light, if you were going to be out on your own for a while.

The first wave usually carried at least two bandoleers per person, it addition to what was in the belt.

Airborne troops usually jumped with several in their pack.

As they established a good supply line to the rear, the load lightened up.

In Vietnam, the ammunition load was increased mainly because, in general, patrols were of longer duration without resupply.

 

[The Alaskan]

So....what I'm getting from the group is "unit of fire" is essentially a meaningless term?

I guess I don't understand if 100 rds per day is NOT the average ammo consumption for an average GI in an average day of combat, then why order and deliver ammo in multiples of 100 rd "units of fire?"

That said, I have no problem agreeing that 100 rds per day would be incredibly light. (I shoot that in one Service rifle match.)

So something is clear as mud.

 

[rcmodel]

So, a Unit of fire would be the same thing as a 'Unit if food' for one solder for one day??

Commander on the phone:
I want to place an order.
Yes Sir!
I want to order 3000 units of food for my 1000 men for breakfast, dinner, and supper tomorrow.
Yes Sir!
3000 units of food on the way sir!!

I never heard the term used in six years in the Army.

I think we called it the TO&E.
https://en.m.wikipedia.org/wiki/Table_of_organization_and_equipment

Then when the SHTF, we called for re-supply.

rc

 

[Vern Humphrey]

"Unit of fire" is a standard military term. It relates to the ammunition supply carried by the individual soldier, by his unit, by a tank or self-propelled howitzer, and so on. While there is a recommended "unit of fire" commanders have the authority to establish units of fire for their units.

TO&E is "Table of Organization and Equipment." It is a list of things issued to a unit, excluding consumables, such as food, ammo, fuel and so on.

Combined with the TO&E is the Table of Allowances (TA) which adds things like tents, packs and so on.

I used to make TO&Es -- it's a complicated process, which involves balancing out related items.

 

[lysanderxiii]

So....what I'm getting from the group is "unit of fire" is essentially a meaningless term?

I guess I don't understand if 100 rds per day is NOT the average ammo consumption for an average GI in an average day of combat, then why order and deliver ammo in multiples of 100 rd "units of fire?"

That said, I have no problem agreeing that 100 rds per day would be incredibly light. (I shoot that in one Service rifle match.)

So something is clear as mud.

Not meaningless, roughly defined in FM 9-6 and adjusted based on local experience.

Why? It saves the S-4 from having to do a lot of math when ordering ammo... If you have 50 effectives and plan on being out of contact with supply for 5 days and expect light enemy contact, how much ammo do you want? If you expect heavy contact with the enemy how much do you want?

And yes, there were "units of food" aka a ration. A K-ration came in breakfast, lunch and dinner packs. A daily ration was all three. So, you asked for one ration per man, per day. Now, they do not differentiate between the meals so "one daily ration" is 3 MREs. (unless you have a mobile kitchen, then it's one MRE, and the Mess Sergeant is stuck with doing some math when ordering food.)

 

[Vern Humphrey]

Logistics in combat operates on the push system -- it's all pre-packaged and pre-loaded, and you'll get it automatically, with no need to send in a detailed order. That's why we use concepts like "units of fire."

 

[lysanderxiii]

"Unit of fire" is a standard military term. It relates to the ammunition supply carried by the individual soldier, by his unit, by a tank or self-propelled howitzer, and so on. While there is a recommended "unit of fire" commanders have the authority to establish units of fire for their units.

TO&E is "Table of Organization and Equipment." It is a list of things issued to a unit, excluding consumables, such as food, ammo, fuel and so on.

Combined with the TO&E is the Table of Allowances (TA) which adds things like tents, packs and so on.

I used to make TO&Es -- it's a complicated process, which involves balancing out related items.

Not quite, (see my above post) the amount of ammunition actually carried (by a person, tank, unit, etc) is defined as the "basic load", and this is set by local SOP, and has to be transportable by organic means.

A 'unit of fire' is no longer listed in the current FM 9-6, as the current doctrine calls for ammo to be 'pushed', rather than 'pulled' from subordinate units. How much ammo gets pushed is based on the calculated resupply rate (RSR).

FM 9-6, MUNITIONS SUPPORT IN THE THEATER OF OPERATIONS

 

[Vern Humphrey]

Not quite, (see my above post) the amount of ammunition actually carried (by a person, tank, unit, etc) is defined as the "basic load", and this is set by local SOP, and has to be transportable by organic means.

How does this differ from what I said?

A 'unit of fire' is no longer listed in the current FM 9-6, as the current doctrine calls for ammo to be 'pushed', rather than 'pulled' from subordinate units. How much ammo gets pushed is based on the calculated resupply rate (RSR).

Ammo has always been pushed -- as I noted in an earlier post. The question is, how much ammo is carried initially. That's the unit of fire.

 

[MagnumDweeb]

My grandpa was a Marine Raider that fought at Guadacanal. Most everybody burned through their ammo and had to pull ammo off of their dead and wounded comrades as he told me. When he burned through the last of his 12 Gauge, another guy a few minutes later caught a round through the chest and my grandpa ran over to him under fire till the medic got there. Once the medic got to work my grandpa sifted through his pockets look for shells because the guy had a Winchester pump action and my grandpa had an Ithaca that he had sent to him from home (his Lt. didn't mind it he said).

After the guy got carted off, my grandpa realized he had nearly gotten shot for looking for 12 gauge ammo. Another guy did a similar thing to feed his Reising.

Guadacanal was a mix of desperate defenses and running battles. I can't imagine anyone getting through a single day with just that load.