[LivingUpNorth]

It looks like an M80 ball round (7.62x51 NATO). It has the NATO cross-circle stamp, and WMA, which I believe makes it Winchester Military Ammunition.

 

[EthansG19]

It looks like an M80 ball round (7.62x51 NATO). It has the NATO cross-circle stamp, and WMA, which I believe makes it Winchester Military Ammunition.

That's what I was leaning towards, but I don't own a .308 or 7.62x51, so I was only going by the limited amount of time I've held the cartridge in the past. Interesting that it doesn't give a clearer caliber marking on the back of the casing.

 

[DirectDrive]

That's what I was leaning towards, but I don't own a .308 or 7.62x51, so I was only going by the limited amount of time I've held the cartridge in the past. Interesting that it doesn't give a clearer caliber marking on the back of the casing.

It's the norm for military ammo headstamps.

 

[EthansG19]

It's the norm for military ammo headstamps.

I don't want to take up too much of your time, but why is that exactly?

 

[garya1961]

Looks like it had a light strike on the primer.

 

[DirectDrive]

I don't want to take up too much of your time, but why is that exactly?

My Internet Guess...
The military uses brief designations probably more for quick identification.
If your M240 needs ammo, you reach for the can that says M80.
If you M4 needs ammo you grab the can that says M855A1.

 

[MarkCO]

Looks like it had a light strike on the primer.

Common with both small and large frame ARs that have floating firing pins.

 

[Villuj_idiot]

https://afte.org/laravel.php/gallery/index/17866

2017 production.

 

[Cav]

It looks like 7.62 mm M118 special ball ammo, used in the M24 and M110.

 

[Bradley T]

AR 10 or SFAR's firing pin bumped the cap a little too.
Military cartridge. The "17" likely means "2017," and probably came in a white box from the ammo cabinet at Walmart.
Probably loaded at East Alton. I have some Winchester M1152 (9x19mm) "MHS" cartridges that have WMA 20 stamped in the head.

 

[e150gt]

Common with both small and large frame ARs that have floating firing pins.

Interesting. The M1A is somewhat known for slam fires that can occur with non military commerical ammo with less hard primers. Hasn't happened to me but I'm shooting mostly military or military clone type ammo.

 

[Lt. Donn]

I don't want to take up too much of your time, but why is that exactly?

Lowest bidder...cost cutting

 

[PEC-Memphis]

Looks like it had a light strike on the primer.

Just means that it has been chambered in a rifle with a floating firing pin (like an AR-10), it doesn’t mean that it has tried to have been fired.

 

[Yoursupremecomander]

The neck is crimped. Typical of ammo intended for use in a semi or full auto.

 

[garya1961]

It looks like 7.62 mm M118 special ball ammo, used in the M24 and M110.

I have quite a bit of 762x51 surplus but would love to have a case of that ammo.

 

[Cav]

I have quite a bit of 762x51 surplus but would love to have a case of that ammo.

Years ago I bought a few boxes at a gun show. Ammo shoots nice tight groups. Still have maybe 20-40 rounds left. Black Hills made some highly rated Military 7.62 ammo, not sure what it was designed as.

 

[collim1]

Chamber a round in most any AR15 and then extract the cartridge out of the chamber and give it a look see. They will all have a dimple from the firing pin.

 

[garya1961]

Years ago I bought a few boxes at a gun show. Ammo shoots nice tight groups. Still have maybe 20-40 rounds left. Black Hills made some highly rated Military 7.62 ammo, not sure what it was designed as.

Some of the best surplus 762x51 I ever shot was Australian F1. It's really good ammo and I shot up about 500 or more rounds just plinking before I knew what I had. Hard to find now but I do have a couple hundred rounds left. I have lots of so so ammo I could have used for plinking.

 

[Jarhead Al]

The real question is how does that round identify? What are his/her/their pronouns?