A constrained Ik rig built in Blender.Aimed at A2/A3. Intended for use with Alwarren's Arma toolbox. Static and hand anims can be exported direct to PBO. Dynamic animations like walk/run cycles can be also be exported directly with some extra work.    I'm not an expert on the internal workings of Blender.Nor would I consider myself a grade A rigger/animator.So bear that in mind if you find mistakes or bugs. 

ArmaRig V6.2 at sendspace.com   ArmaRig V6.2 at Filedropper.com   ArmaRig_V6.2 at Armaholic.com   VIDEO
A brief video where the rig is used to generate a couple of rtms.I use Alwarren's
Arma toolbox.     Another short video describing how to use one of your own meshes as a reference within the blend file. The process can be applied to any of the reference meshes.   This video describes my own method for "zeroing" out an animation before exporting. This helps to avoid the distance doubling and also looping back on itself. Which happens as a result of the step value being added to the animation on the relevant axis.   https://www.dailymotion.com/video/x3dx5ai_zeroing-out-your-animations-for-export-to-the-arma-series-games_videogames   Naming convention: As Pufu pointed out, you may need to switch the bone name for the weapon to lower case for A3.   "weapon" as opposed to "Weapon".   This is easily done from the bone tab in the properties window, with the armature selected. Either in edit mode or pose mode. It can also be done from the outliner window.