The Bolt Pistol used by Space Marines in Warhammer 40000 table-top combat game is as iconic as the Bolter in the science fiction world. Today, when I am building the airsoft Bolter (see "Cross-Reference" below), I realize how easy it is to build an airsoft Bolt Pistol using the M4 as base.
In this article, I will walk through the process of building a functional airsoft Warhammer 40K Bolt Pistol through the use of off-the-shelf M4 parts. You can then use the M4 Bolt Pistol as-is, based on the resemblance, or continue to improve the base through sculpture modeling.
To test the feasibility and perform a rapid prototype, I have used the Pimp My Gun site (see "Related Links" section below). Pimp My Gun allows you to assemble guns virtually using a selection of models. I have used its list of standard M4 parts to assemble the base of the airsoft Bolt Pistol. The result is shown in the design below.
As you can see in the comparison images below, the assembled M4 pistol has a huge resemblance to the Bolt Pistol. The only thing that the airsoft version is missing is the short butt stock.
So far, all the parts in the design are off the shelf airsoft parts. Therefore, you can see that is quite feasible to build an airsoft Bolt Pistol. How closely you want it to resemble the Warhammer 40K Bolt Pistol depends on how much sculpture modeling you are willing to perform afterward. In the next section, I will show you all the off the shelf part that are used in the design.
The exploded parts view below shows all the parts for this airsoft Bolt Pistol. Keep in mind that it only shows the external parts, not the internal parts.
The first part was the receiver. In this case, I picked the HK416, because it had a great resemblance to the Bolt Pistol receiver. Next, I picked the AG-43 handgrip, because it had the finger indention similar to the Bolt Pistol handgrip. It was difficult finding a matching magazine. The HK417 20 round magazine is about the closest part I can find it. The KX3 flashhider will match the Bolter quite well, but will require modifications.
As you can see, all these parts are readily available in airsoft or real firearm versions. In the next section, we will look at making this Bolt Pistol an airsoft reality.
Just getting all the external parts to make it look like a Warhammer 40000 Bolt Pistol is one thing, but to make it work as an airsoft pistol is quite another. For example, where are you going to put the battery if you go the electronic route?
There is really no space anywhere for the battery. Your only choice is to add a battery box to the outside of the pistol. But that would defeat the purpose of this replica. Therefore, I suggest you go the gas route. Maybe that's why most airsoft pistols are gas blowback (GBB).
If you go the gas route, your work is done. You just get gas internals and gas magazines and you are ready to play.
The flashhider is a problem. The KX3 flashhider is far too long compared to the flashhider on the Bolt Pistol. But with a hacksaw, you can cut it down to size. Then you'll have to glue--or perform alternate modifications--it to the receiver.
You can make the base M4 airsoft Bolt Pistol look more like the real thing through sculpture modeling. Sculpture modeling is the working of material to build up form and shape. You'll want to keep in mind of the airsoft functionality, so the shape you model should be easily removable from the airsoft base, yet won't fall apart on the airsoft battle field. Keep in mind how the receiver separates (see image below). When you model, be sure to account for serviceability of the airsoft gun.
I am not a sculpture modeler, so this is as far as I will go with my airsoft Bolt Pistol. But if you are inspired to make a model for it, please feel free to expand this article on design and on instructions.