Take a look at this 4" swivel vise at Enco:
http://www.use-enco.com/CGI/INSRIT?PMAKA=425-7541&PMPXNO=952025&PARTPG=INLMK32
I bought one similar to it 40 years ago from MSC. It was $25 plus freight then. The one Enco has looks to be a little heftier than the one I got from MSC. I have always been happy with the one I have and use it a lot. It says 100 on the side meaning 100mm or 4" I assume. Weighs 26 pounds. I think they are still around but I do not know where to look at the moment. The one at Enco has a covered screw. Mine does not. So that is going to add some to the weight. I would assume it to be around 35 pounds.
Also, take a look at:
http://www.tools4cheap.net/proddetail.php?prod=tilt4
Here, this 4" Vertex machine vise appears to be very nearly identical to the 4" vise I have that came from MSC so long ago:
http://www.ebay.com/itm/ACCURA-VERT...0?pt=BI_Tool_Work_Holding&hash=item5659f00668
It looks like it has the same cast iron handle that mine had. The handle fell off, as a milling machine vise crank handle will do if you forget to turn it around and put it on backwards, and broke when it hit the floor. I replaced the broken handle with a nice forged steel Fairmount handle but those I believe are no longer available. You will look for a long time to find the right Fairmount handle on eBay and then likely have to pay a somewhat hefty price to get it. Great vise otherwise and the price is right! This vise will weigh about 26 pounds.
I see Martin Tool acquired the Faimount product line and the 9/16" bore x 4" C to C x 5-1/8" OAL crank handle, just like my Fairmount handle, is still available as Martin Part Number CH4B. It is available at McMaster-Carr for only $61.02. McMaster-Carr's drawing is dimensioned a bit differently than the drawing in the Martin catalog.
See Martin's Industrial Hand Tools Catalog at:
http://www.martinsprocket.com/products/industrial-hand-tools
and the crank handle in McMaster-Carr's catalog, which certainly must be the Martin product, at:
http://www.mcmaster.com/#6040k15/=oapxj0
The genuine forged steel handle costs half as much as the Vertex 4" Vise. You will need the new handle the first time the cast iron handle hits the concrete floor. At least then you will have a nice Made in the U.S.A handle to go with your nice Made in China Vertex 4" Vise. The forged steel handle will not break when it hits the floor which it is bound to do.
Kent in Toledo