Not sure with a 15mm hole.  I asked a friend of mine that is heavy weapons and still active duty.  He told me it could possibly be a 20mm APDS (Armor-Piercing Discarding Sabot).  These rounds are usually used by the Navy's Phalanx system MK149 but have a 15 mm (0.59 in) penetrator encased in a plastic sabot.   But it could be some ATEC weapon that never made it past trials.   Either way, I would not want to be on the business end of that weapon.

Hello and welcome to the forum!

Great you have the jacket. And other patches. Both are worth a lot for someone who remember a family member.

I agree with GatorDoc. DU round.

Just picked this up. The name came right up in an obit. And the card it's pinned to is, I think, a high school calling card.   I got these when I was graduating high school. Even got a scrapbook to keep other kids' cards. I think the deal was you gave them to whoever opened the door, like your maid or butler, and they'd bring the card to the master of the house and they'd decide if they'd let you in. Did everybody get calling cards with high school graduation?  

It's likely a M-H 3rd  model,single action "pocket army" in 44-40 Winchester centerfire, with some original blue finish left on it. Blue was the standard finish and nickle was optional.  The 2nd model had a barrel wedge, no top strap and "scooped" cylinder flutes. The 4th model was made in mostly 5-1/2 inch barrel lengths.  There was no 1st model of the pocket army.  Interestingly, these models could be ordered with two different barrel sets, such as a 3-1/2 in. and 7-1/2 in. Judging by the looks of the bolt wear on the cylinder, this pistol has worn or broken internal parts. Sadly, parts for these pistols are almost non-existant! I have a 2nd model with 3-1/2 in. barrel that had a broken trigger return spring when I bought it. With no parts to be found, I made the spring myself and had a buddy heat treat it and it works perfectly now.  Until you disassemble it, you won't know what is wrong with it and it will diminish the value greatly.  Take a look at GunBroker to get an idea of the value for it, I've had mine for about 25 years and haven't kept up with prices on them. They are pretty cool pistols and have almost a cult-like following today, so it would be worthwhile to repair it for achieving the maximum value.  Merwin-Hulbert tried to secure government contracts for these pistols but unfortunately never did. They were very well made and have become quite collectible in the last 30 years or so. Here's a not too good photo of mine: Thanks for posting this--even if not military!      Steve

. Emmanuel is not only a Jeep fanatic, he is also an amphibious vehicle fanatic, he has owned two DUKW's, two or three amphibious Ford Jeeps, German Schwimmwagen and and at one time owned an extremely rare German amphibious Trippelwagen, an example attached below.      Norman D. Landing, Forum Normandy Correspondent, May 18  2O25.    ….    

On EBAY this morning.  Currently $15.58 with three days to run.  Philippine made?   Medical Corps officer?       

Travelling in style, looks amazing. And good job preserving one of these, can't be many left now. AG