Archived-FU

This can be done for many many guns.  The idea comes from David_Bowie (something like that) and his Barretta Barrel.  This was done on my RF100 to detach the side of the gun.  Here is the writeup-

Materials-
PVC Pieces (1in) x2
(http://i75.photobucket.com/albums/i293/General_Cole/PVCPieces.jpg)
Guru
(http://i75.photobucket.com/albums/i293/General_Cole/141.jpg)
CPVC Sticks (1in) x2
(http://i75.photobucket.com/albums/i293/General_Cole/CPVCPieces.jpg)
Hot Glue
Manta Ray
(http://i75.photobucket.com/albums/i293/General_Cole/MantaRay.jpg)
E6000 (Adhesive available at Hobby Lobby)


Tools-
Ratcheting PVC Cutters
(http://i75.photobucket.com/albums/i293/General_Cole/PVCCutters.jpg)
Hot Glue Gun

First get your gun.  In this specific modification we will be using the Manta Ray and Guru.  I placed the CPVC sticks on the Manta Ray in the back, on the shield in the gap in the rear, and the other centered on the handgrip.  Use lots of hotglue. Then place a large amount of E6000 on the tow pieces.  It will make it incredibly hard   Then take your PVC cutters and cut the PVC pieces lengthwise at about a 60:40 ratio.
(http://i75.photobucket.com/albums/i293/General_Cole/PVCCutting.jpg)

The finished pieces will look like this-
(http://i75.photobucket.com/albums/i293/General_Cole/CutPieces.jpg)

Pop these pieces on the CPVC pieces on the Manta Ray.  Put a massive amount of Hot Glue on the PVC sections and press the whole gun onto the other gun, the Guru.  I placed it on the top, on the rail, with the back of the Manta Ray on the place where the original barrel of the Crossbow was.  Let the pieces dry and twist the Manta Ray off.  This is what it should look like-
(http://i75.photobucket.com/albums/i293/General_Cole/WithoutMantaRay.jpg)

This is what the gun looks like with the Manta Ray on-
(http://i75.photobucket.com/albums/i293/General_Cole/HeadOn2.jpg)

(http://i75.photobucket.com/albums/i293/General_Cole/Side.jpg)

EDIT-
Yea, I know its impractical.  I know it will not see use before I take it off.  It was a technology demonstrator.  Not a working weapon.  I mean, a Manta on a Crossbow?  No.  SMDTGs and 2Ks maybe, but I knew I wouldn't use this.  The point is that it allows for hardpoints to modify your weapons.

I think it looks sweet. It doesn't matter if it functions because everyone will be running away.

Probably the easiest way ever to make a bracket system.

The only problem that I see is the connection being able to slide apart somewhat easily. Or, is there enough friction between the PVC and CPVC to prevent that except in the worst case scenario?

If there is a good amount of friction you can add a layer of E-tape.  It is decently hard to get off the main gun.  But not take it apart difficult.