Without you maxing out your lockpicking skills and coming back for it later, Dogmeat can somehow just fetch it for you. Completely proven. Might want to try now before a patch decides to fix this little shortcut.

Pretty sure is already fixed. Dogmeat was unable to go down the elevator yesterday, even by telling him to "Stay" at the center of of the platform.

Don't think that matters as companions will teleport to you after a while.

That's because Dogmeat has Locksmith Rank 3. He's cool like that.

This still works. I just tried it. Go down the elevator. Dogmeat will be waiting for you at the bottom.

Doesn't work for me either. Tried it an hour or two ago. He'd go and pick up the ammo in that room when I tested it, but wouldn't get the gun.

Doesn't seem to work for me. I'm on PC

Get your dogmeat near the Criolator cabinet and ask him to bring you items.

I tried it as well, and it didn't work on PC. Asking him to find items caused him to walk over to the case and point it out, but he didn't actually grab the gun itself.

I'm on pc. I was standing on the outside of the cage when I asked him to fetch. Try standing just between the metal cage and the overseer's desk. Don't stand near the door or he just goes down the hallway.

Thanks for the post, I am on Xbox One, and just got it. In most cases I think I would have forgotten this when I leveled up my lock pick skill. Now to find some ammo for this baby.

Trade with Dogmeat. He should have the ammo in his inventory. I rewarded him with a nice red bandana! Good dog!

I finally got it to work. Tried telling Dogmeat to open the case, and he wouldn't, so I finally tried having him search for an item. He grabbed it on the first try. Thing is, this was on my sister's character. Now to do the same on my character. Probably not going to use the thing, but it's unique, so I have to have it.

You must have your Dogmeat INSIDE the 'cage' with that weapon on the wall and ask him to fetch via 'talk' dialogue.

Then you'll get your weapon.