3D Modelling on J.A.C.K.

Recently Erty released a program capable of turning RMF and JMF to SMD, wich is pretty cool. I had the idea of attempting to make a 3D model entirely on J.A.C.K., to test and see if it was a good idea, or if it was better than normal modelling with standard 3D modelling software.
So, to start this, i tried to make a v_shotgun, and after some time i created a very basic model Wich is based on a random stock picture of a Remington (it looks more like the TF2 shotgun). Anyways i "compiled" the thing and honestly it did looked better than i expected: The only thing left now was rigging and testing, however i found quite a lot of issues when doing this (that luckly were not caused by the converter).
1. The pump-thing was incorrectly placed.
I forgot that the pump is located really far away from the barrel end, and that the hand would not be able to grab it. I could edit the model in MS3D, however i wanted to fully model the thing in J.A.C.K, so that was definitely not an option.
2. The barrels are too short and the rest is very large
In the pumping animation, Gordon cocks back. This was an issue, since the pump was very far away from the hand, and i did not wanted to edit the animation. So, i had to edit the reference to make the barrels longer and the rest shorter: I edited the reference and added some more details: Now it was time to rig and compile, but during the rigging process i ran across a problem. I dont know exactly what i did, but i "erased" the backfaces in the pump after i converted. At this point i was very tired and it was really dark outside, but i needed at least a reference or a concept. So i quickly deleted the hands, moved the viewpoint, and compiled. CONCLUSION/TL;DR: Most of the problems i encountered were a skill issue of mine, but an experienced mapper and modeler should be able to use mapping tools to create 3D models easily.