There are really only two big secrets to this conversion: Secret number one is the diameter of the plastic rod used for the barrels, which is 2.5mm. Secret number two is the length of the new barrels, which is 1.25 inches.
Trim your barrels with four cuts in the floowing places. When you cut the side closest to the ammo drums be sure to watch out for the little black nubs - you dont want to cut those off on accident, it will make it look funny later. So be sure to slow down and take your time. Here you can see the original barrels cut out and the new barrels placed under them.
Now you need to use your pin vice and 2.5mm drill to counter sink the flash supressors and the other side of the barrels by 1/8th of an inch. This is why the new barrel inserts must be 1.25 inches long, becuase you are going to use .125 inches on either side to get the rod glued into the weapon assembly so that the conversion looks seamless. Here you can see where the 1/8th of an inch deep (.125 inch) holes were drilled on either side.
After your holes are drilled, dry fit the new barrel extensions and then glue them in place as you can see from the measurement markings on the mat (each square is one inch by one inch) the overall extension ends up being one inch, almost 3 times longer than the original.
This is a very simple a straight forward conversion that hides all the glue points, cut lines and makes the modification look like it was built that way - which is exactly how we want our modifications to look!
In total converting both weapons took about 20 minutes, allowing me to go from stock:
I hope this helps give some of you guys some ideas!