Tutorial: Converting an Umbra Pattern boltgun

From top to bottom: Primaris Auto Bolt Rifle, Umbra Pattern Bolter (MKVI HH marines), converted Umbra Bolter.

Over the years I have converted multiple more realistically-scaled boltguns, including a SMG styled one based on a Delaque flechette pistol and one from a Primaris heavy bolt pistol. I even created a tutorial showing how to convert a boltgun scaled to suit a Sister of Battle. Despite all of these conversions, I never actually made a tutorial showing how to create a boltgun variant for Space Marines. With the recent release of the Horus Heresy MKVI Space Marines, I thought it would be a great opportunity to take one of the new beakie marines and convert their Umbra pattern bolter to be smaller and ultimately more sensible.

Using a razor saw, cut off the upper section of the bolter.

Using a razor saw, cut off the rest of the bolter muzzle extending from the foregrip.

Using a pinvise, drill a 0.8mm hole at the front of the bolter. This hole is where the new barrel for the weapon will slide into.

Using a razor saw, cut off the rest of the bolter above from the foregrip.

Using a hobby-knife, cut off a section of 0.8mm brass tubing to serve as a new barrel for the bolter. An additional piece of 0.6mm brass tubing can be cut and slide into the 0.8mm tube to add additional detailing. To safely cut brass tubing without crushing it, simply apply the blade of a hobby knife to the tube and slowly roll the tube while applying pressure with the knife. This will allow you to get a controlled cut around the entire circumference of the tube.

Using a razor saw, cut off the barrel brace under a Delaque lasgun. Layer the piece of the lasgun on top of the barrel to partially shroud the barrel.

Carve away some of the front of the bolter magazine to make it better scaled to the cutdown bolter. Use plasticard and other bits of plastic to add additional details like a rear sight.

Using a razor saw, cut off the stock of the Delaque lasgun used earlier.

To finish off the conversion, glue on the stock and add any additional details, like a front sight.

From top to bottom: Bolter variant converted from a Heavy Bolt Pistol, Bolter variant converted from Umbra Pattern Bolter.

I hope you were able to follow this tutorial and find something useful with it! It is nice to finally create a tutorial for a Space Marine sized bolter. Ultimately, the bolter is still pretty large. Maybe I will make an even smaller one?!

- Adam Wier