Interesting find. Naval Board of Ordnance (The Bureau of Ordnance (BuOrd) was a United States Navy organization, which was responsible for the procurement, storage, and deployment of all naval weapons, between the years 1862 and 1959.) 
Can you take and post a picture from the front looking at a slight angle down on the anvil of the press?
Famco still exists today making presses that look about the same. I guess if you have a good product, why change.

That was my thought… it was designed as an arbor press then adapted to priming and designated as such.  The basic shape resembles a basic arbor press too much to be coincidental. 
It looks like it might actually be too strong.  I’d be concerned about crushing primers.
JMHO - Froggie

Bureau of Ships ( BUSHIPS ) and Bureau of Ordnance 
( BUORD) were supply branches of the USN I believe were created before or at the start up of WWII and liquidated during the Vietnam era. Both of these branches are now rolled up into NAVSEA which oversees all branches of the USN.   

Famco, Greenerd and Dake made arbor and other presses for general shop and production use. But along with just plain arbor presses they would contract to supply special ram tooling for specialized applications. I would guess they made hundreds of special presses for the USN, aircraft companies, you name it.  One thing for sure,  you won’t wear your press out, maybe you arm. I had a small Greenerd made from Beryillium Bronze. Came off a decom MSO class minesweeper so was non-magnetic. 

Rick

Also, those four holes on the legs would make it simple to securely locate any kind of adaptor plate needed.  Of course I’m looking at that beast and dreaming of how well it could be used for case forming… even the most severe case forming.   
Froggie

Just looked up your Famco E model and it’s a 3/4 ton press. I’d guess a 1/2 to 3/4 ton press would easily resize any brass without too much power. Nice catch

Rick

I've had a machine shop, since the mid '70's so, I've had a arbor press for a long time.

This is my first one, a 2 ton Greenard. In about '88, I bought a 3 ton for the shop and moved this one, into my loading room. Years before, I reamed a .501 hole in the ram, with a set screw to hold punches and put two 3/8 x 16 threaded holes, in the base and made the 2" die holder for it, to punch holes in aluminum sheet, for a job I had. After bring it in to the loading room, I made 3 dies and punches (30, 32 & 45 cal) for it, to punch out 1/16 LDPE wads. The set screw, next to the punch hole, is to auto index the LDPE so, that there is no waist. It works well and pretty fast for that. I've also used it to swage cast and jacketed bullets.

The aluminum plate, has a .501 reamed hole in it, that was done to hold the CH style shell holders, that have a 1/2 x 20 thread, on the back side, as seen. I did most of my case forming with it. I just took a piece of 3/4" to 1" HRS or CRS, turn a 1/2" shank on the length I needed and made a cavity, either with a chamber reamer or a boring bar to size brass, to fit my chambers.

L to R, on the arbor press, is a piece to protect the hole and face of the ram, for regular press work, a expander  for necking up cases and a adapter to hold Lyman sizing dies. In the tray are a few of the dies I've made, for case forming and some misc punches. I also used it for pushing pins, in and out of actions and other parts.

For me, I think a 2 ton press, is a ideal size. It gives you lots a room, to work around for reloading things and is very versatile for other things, when set up like this.

As for pressure, you can exert as much or as little, as you want or need by extending the handle, to different lengths, or even adding a cheater bar as opposed to a press that works on over center, linkage leverage. Actually you can feel very minor changes in the pressure needed. The gear, acting on the ram, has much less direct press, than a loading press. It's the leverage distance, exerted on the gear, with the handle, that creates most of the pressure.