There's a couple of parts that make up the "connector" (and different SG builds handle it differently, of course).
For a few pics of the currently-believed-to-be screen accurate method, check out the thread Moosh linked too.
Quoted from Pg 11 -
M56 Smart One wrote:
... Matsuo has addressed fitting the C-clamp to attach the L-bracket to so that I can attach the gun to the steadicam arm...
Attachment:
Adam Marsh-Smartgun clamp.jpg [ 93.88 KiB | Viewed 1911 times ]
Also check out this thread (as it shows off the L bracket you [probably] need to clear the drum mag) -
http://forum.alienslegacy.com/viewtopic.php?f=3&p=242975Quoted from Pg 3 -
bigbisont wrote:
... For the gun bracket I will be trying to get screen accurate, for the attachment to the vest...not so much.
Attachment:
Bigbisont SG L-bracket 01.jpg [ 125.01 KiB | Viewed 1911 times ]
On the other end to connect to the gun, I layered up a "C" bracket. It hugs the gun in a screen accurate location. 2 tiny screws are in the top 'legs' and one large bolt runs through the 'counterweight' cylinder and up into the barrel cover.
Attachment:
Bigbisont SG L-bracket 02.jpg [ 145.74 KiB | Viewed 1911 times ]
Attachment:
Bigbisont SG L-bracket 03.jpg [ 183.83 KiB | Viewed 1911 times ]
And for my own, I've bolted a Kessler Crane ball joint straight into the gun body (doesn't quite have the clearance around the drum mag, but SGs are always I work in progress, I reckon -
Attachment:
septic SG - Kessler Crane ball joint.jpg [ 479.66 KiB | Viewed 1911 times ]
I'd recommend reading through all of the build threads linked here -
http://forum.alienslegacy.com/viewtopic.php?f=7&t=17377 (the two threads mentioned in my/Moosh's posts are also listed here).