Posting for a friend here. I didn't take the pictures or see this in person. It's what I have to go on. Any ideas?

Sure would be a whole lot easier if some measurements were taken with calipers.

Measurements, clearer pics of the case head and writing on the bullet, Steel or brass case all might help. Primer is unusual though and looks like it could be crimped. Bullet looks like it could be lead with some writing on it, but cannot read all of it.

Quick run through in Cartridges of the World it looks somewhat like 460 A-Square Short or JDJ 500 Whisper as far as the case but not exactly on either.

Looks a lot like the 13mm German M131 machine gun round from WW II. It's definitely of military origin based on the head stamp and matching writing on the bullet.

Put some paper over the end and rub with the side of pencil lead for a better peek at the stamp.

Gas Guzzler posted this for me as I'm not techy enough to post the pictures.

Asking for info for a friend, I DONT HAVE THE ROUND. The friend says the head stamp looks like nhr 26 44 the bullet looks like.4u7 & auv. The case and bullet test as magnetic, all steel.

No big deal here so dont get your drawers in a wad.... I just figured some of the spurts on THF might know the answer.

Thanks for looking.

Looks like you could be right. dnite, maybe get your friend to buy that if it's still where they found it.

He did buy it................ $40.00, but if you are collecting that may be cheap.... like land they're not making anymore.