First, start by creating a cylinder. Add editable poly modifier, and modify by your taste. At the end, use turbo smooth modifier to get smooth result.

Now... Add another cylinder on top to make it a stand. For details on designing, copy the one we first created, and re-size it to fit on top as some kind of bracket.

In this step, make a capsule. Re size it, squeeze it, do whatever you want to make the body of your turret. I made two, one for body and one for ammo storage (use your imagination :))...

For turret make bunch of tubes, re size few of them to make them "hold" the smaller ones (barrels). At the end put a sphere just to give it an interesting look :)

Make a box and place it as a "turret holder"... Duplicate the turret to the other side.

Now, the harder part, making the muzzle flash.

Start by making a sphere. Add editable poly in modifiers. Select the top poly dot and then go down in modifier menu and select "soft selection", now, play with options and make sure the blue color is on the bottom of sphere. Pull it up.

This is what it should look like... Now disable soft selection and randomly take some "poly dots" and pull them up to make it look more like a muzzle flash.

Place the modified spheres where muzzle flashes naturally are. :) Add materials.

In renderers, pick mental ray. I used few materials from mental ray. For muzzle flash, I used an architectural material type, made it yellow, added some red & yellow noise and increased luminance for glow effect. I also played with some other settings to achieve the stronger glow, cannot remember at the moment.

And for the end, to get results on materials that reflect, we should add a hdr image. I make big sphere over whole scene. Tick the 2-sided option, make diffuse and ambient black, and tick self-illumination color and make it black, click the button on right, choose bitmap and import a hdr picture and apply it to sphere. Oh one more thing, add a light source, I used omni light ;)

I found my hdr image in a youtube 3ds max mental ray tutorial, video description, so here's the download link sitebuilder.yola.com/sites/Dc44/D7eb/D501/Dc4e/U8a4986cc1fb781c1011fe4c105be744c/8a4986c92146f75801214a4e25712bf4/resources/office.hdr Good luck!