When I posted the picture of my truescale terminator the other day, I was asked how I converted his stormbolter. I'd made it look like the older metal ones with two individual gun barrels instead of that one piece blob that's on the front of plastic stormbolters these days.
The conversion is quite simple and takes no time at all. The idea came from the post I did a while ago showing how you can repair a gun barrel if you happen to damage it while drilling it out.
I figured if I could repair one by making a new one, I could make two new barrels and change the look of the a current stormbolter back to the old school style.
What you'll need to pull this off
Aside from your hobby tools and a stormbolter, you're going to need two different sized rolls of greenstuff. I suspect you could do this with plasticard tubing as well if you went hunting and found the right sizes.
One roll needs to be the same thickness as a normal gun barrel and the other roll needs to be much thinner so it can be used as the small stud mounted in between the barrels on top of them.
Converting the stormbolter
The first step is to carefully cut away the barrels on your existing stormbolter. Be careful not to damage the small, flat mount on the underside of the barrels. One thing to pay particular attention to is the surface of the front of the weapon once you cut the barrels off. You want that to be as smooth and flat as possible.
One you have the weapon modified, it's a matter of gluing two new sections of greenstuff rolls in place of where the gun barrels were located. Pay attention when lining them up. You want them to stick out straight from the weapon. If they're off or they're angled, the effect will not work and the gun will look weird.
You don't have to worry too much about them being the same length since you can cut the fronts off once they are glued in place so they match up perfectly. Make sure to cut the muzzles off nice and straight as well. If need be, use a file to get them as close to perfect as you can. The slightest irregularity and they will look "wrong."
Once you have both of the new gun barrels in place, you can add the smaller piece on the top in between them. This is just a shorter and smaller diameter piece of greenstuff that is glued down right in between both barrels.
Once everything has had some time to dry, you can drill out your gun barrels. I start with the side holes and then do the fronts. I also expand the front ones slightly to give the gun a more menacing look. The larger muzzle openings indicate a larger caliber weapon to me and that just looks way cooler.
The end result is a subtle conversion that can be overlooked quite easily. But it adds additional detail to the weapon and makes it look a little more believable I think.
Make sure to check out these posts as they might help:
How to make terminator combi-weapons
How to fix damaged gun barrels