Space Marine Weapon Conversions

Anyone familiar with this project will have noticed a lot of converted weapons present among my Space Marine models. I’ll detail the processes for creating them, the reasons why I created them, and share the in-universe fluff for these particular variants.

Horatius Pattern Bolt Pistol Sidearm

bolt sidearm

A defensive weapon, it has a six round magazine, and was named after a legendary Space Marine hero whose troops held a bridge for a day and a night against an onslaught of Orks before reinforcements could arrive.

The idea behind this weapon was to create a sidearm that actually fit in those holster bits that come with the Space Marine sprues. I wasn’t worried about it being an exact fit. I just wanted it to be close. The pose on the model above was based on classic pistol presentations for combat shooting. A Space Marine in power armor may or may not even need to worry about fundamentals when he has servo-assisted armor and targeting software, but hey, he had to learn as a Neophyte and Scout and old habits die hard.

What You Need:

  • Space Marine Bolt Pistol


  • Space Marine Vehicle Gunner Arms
  • Space Marine Bolter Left Arm

355969_md-Bolt Pistol, Holster gallery_64093_6671_4499


  1. Trim off the Barrel, Top Sights, and the under side of the pistol along the axis of where the Marine’s hand will meet the weapon.
  2. Carefully slice the bolter in hallf down its length from the top to bottom.
  3. Use a file to take an equal amount of plastic off both halves.
  4. Glue the two halves back together. Glue the magazine to the bottom of the weapon.

Pose Tutorial:

  1. Cut right arm free from Space Marine Vehicle Gunner Arms bit.
  2. Carefully trim thumb off the top, set aside.
  3. Shave/file trigger group away, then glue thumb back to the side of the hand.
  4. Cut hand free from left arm, rotate to grip front of firing hand.

Drum-fed Heavy Bolter

heavy bolter

I created this because I didn’t like the aesthetic of the giant backpacks and the unweildy belt feeds, and wanted my Tactical Marines to have a more portable, versatile support weapon. Subsequently, Games Workshop went and added this style of Heavy Bolter to the Sternguard kit. So you can technically just buy that kit, or the bit off EBay and save yourself the effort. But if you have the old style of Heavy Bolters lying around, here’s an easy and quick way to make them look cooler.

What You Need:

  • Space Marine Heavy Bolter (2 parts)
  • Space Marine Devastator Ammo Drum


  • Eldar Ammo Bit
  • Tyranid Hive Tyrant/Carnifex Claw

heavy bolter diagram


  1. Cut cabling and ammo belt away from Heavy Bolter housing.
  2. Cut handles off Devastator Heavy Bolter Ammunition bit.
  3. Attach Ammunition Drum to bottom of Heavy Bolter.
  4. Some fiddling with the firing arm will be required since the arm that comes with the Heavy Bolter has a bunch of cables built into it. You will need to file the cables off, or better, use a Space Marine Bolter firing arm and re-pose it.

Cerceus Pattern Boltgun

cerceus bolter

Based off the ruggedized frame of the standard Godywn-Pattern Boltgun, the Invectors Chapter Forges on Cerceus IV created the Cerceus-Pattern Boltgun in M35. Elevating the barrel and feeding mechanism served the dual function of simplifying the internal mechanism which increased reliability, and allowing the use of higher capacity sickle magazines without increasing the overall dimensions of the weapon. The slight increase to weapon recoil caused by the higher bore axis can be problematic for regular human troops, howvever it has proven manageable for the genetically modified Marines of the Scout Company, and is fully compensated for by the power-assisted battle plate worn by the line companies. The weapon features the standard targeter array linked to the Marine helmet’s auto-senses, and protected flip-up sights are contained in the weapon’s housing for unassisted aiming. While relatively uncommon, the Cerceus-Pattern can found service in other Chapters in the Ultima Segmentum.

I made this weapon because I’m a masochist and it doesn’t already take enough effort to build 40-part Space Marines. Well, that and the fact that I wanted a more “realistic” looking bolter. This meant lining up the barrel with the ejection port. I then decided to take off the exaggerated front sight post for aesthetic reasons.

What You Need:

  • Space Marine Boltgun
cerceus diagram
Tip: Always drill the barrel before cutting it loose. It will save you a ton of headache.

This one is fairly easy.


  1. Drill the Barrel.
  2. Optional: File/Shave Front Sight Post.
  3. Cut Barrel and Targeting Nub Free.
  4. Glue Barrel back in line with the ejection port as shown.
  5. Glue Targeting Nub below Barrel.

Graia Pattern Storm Bolter


This weapon is named after the Forge World in the Warhammer 40K: Space Marine video game. I had actually created this variant independent of the video game, but it seems fitting to name it after the game’s planet since the planet was a Forge World, and they share most of the same design cues.

What You Need:

  • Space Marine Terminator Storm Bolter
  • Bit of Sprue or Grip from Space Marine Bolter

stormbolter diagram


  1. Cut Space Marine Terminator Arm free.
  2. Cut Ammunition Drum off, move back in line with gap behind housing. Line up feed with the gap, as the gap will serve as the weapon’s ejection port.
  3. Using bits of Sprue, fashion an under-barrel grip, and then add a length to the rear of the weapon. Texture as desired.
  4. Drill out Barrel
  5. Optional: Shave off Front Sight Post.



I created this for two reasons. First, Space Marine close combat weapons are comically huge. Second, the Gladius is Roman and thus fits the Space Marine aesthetic (well, except maybe the furry ones) and I love that period of history. I based this on the classic wasp-waisted Mainz and Hispaniensis style weapons. This will look small until you realize that it would, to scale, still be like four feet long.

What You Need:

  • Space Marine Power Sword Arm
  • High Elf Archer Command Sword

gladius 1


  1. Cut blade free of High Eld Archer Command arm. Shave/File remainder of Gem.
  2. Optional: Carefully shave off Skull and Power Cables from blade of Space Marine Power Sword Arm. Set aside.
  3. Cut blade free of Space Marine Power Sword Arm.
  4. Attach High Elf sword blade to Space Marine hilt.
  5. Optional: Reattach Skull and one Power Cable (two will be too cluttered)

Cerceus Pattern Assault Flamer

331471_md-Special Weapon Marines

This was one of the first weapons conversions I made. Really, I just wanted a shorter, more compact flamer because I thought that the base model was too long, with pointlessly long tubes. The Rogue Trader and 2nd Edition flamers were much more compact, which befits a force like the Space Marines who wil do a lot of fighting in tight confines like space vessels (where it probably isn’t a good idea to use oxygen-consuming weapons like flame throwers, but hey, Rule of Cool right? Besides, Space Marines have contained life support). Like the Cerceus Pattern Bolter, the weapon is named after the home system of the Invectors Chapter of Space Marines, where the Chapter Forges that invented it reside.

What You Need:

  • Space Marine Flamer

space marine flamer diagram


  1. Cut Nozzle off of Flamer.
  2. Cut tubing off flush with grip.
  3. Glue Nozzle back to the body.

Do you have any exciting weapons conversions you’d like to share?  Questions? Comments? Leave one below!

Related Article:

Space Marine Conversions

Tutorial: True Scale Space Marines


Space Marine looking at Facebook

2 thoughts on “Space Marine Weapon Conversions

  1. ‘Leave no model unconverted’ – there’s a slogan I could live by! Cheers for the tutorial, some useful tips here that I might be trying out myself. Especially like the Horatius bolt pistol – as you say it may not be strictly required for a Space Marine to hold a pistol like that but it looks good and adds a little ‘real world cue’ that helps make the model that bit more gritty and believable.
    Rather like the stubbier, more aggressive look of the flamer as well, it makes the model look that bit more bullish – just right for a Space Marine. Cheers!


    1. Glad you like them. I definitely like the shorty flamer. It makes it more compact (which is good considering how much space the Marine takes up by himself. For a lot of people, you’d want the flames being thrown as far away from you as possible, but I feel like that’s less of a concern for a power armored Space Marine. The smaller bolt pistol was more of a “How do I make a bolt pistol that fits in the holster” concept. Mostly important because I have a ton of Space Marines with holsters (and a ton of holster bits sitting around waiting for a new Marine to be assembled to have them). I’ve only ever made the one, but the concept holds up. I’d love to make slimmer bolters, but the idea of cutting apart that many bolters is fairly daunting. And I don’t need any more excuses to put off painting them. I’ve finally gotten the liquid green stuff working on doing the final gap fill and smoothing on some of them.

      I’ve got some more weapon conversions to post up that I’ll get around to eventually.

      Liked by 1 person

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