Something's wrong with soldier unit addons with OFP: Resistances new pistols!
OFP addon maker MrCrispPacket filed this report regarding tests he made with his own addons:
I've found that for whatever reason my campaign addons which I created, a modified BlackOp and General Guba, were not able to use the new pistols properly. The pistol model didn't appear in its hands and the fire and muzzle flash came from where a normal rifle would fire from.
I assume this is due to the fact that the old models do not support the new pistol animations. Indeed, the problem was solved when I updated both of my addons with the new models from OFP: Resistance's Data3d.pbo file.
If this is true of all models, then it means the dozens of previously made unit addons will not work correctly with pistols and will need to be updated.
My squadmate, Veit, sent me a more detailed technical explanation of the problem:
Whenever some model is added to another model it can only show up on the other model if there is a so called 'proxy' on the other model defined. For instance: If you mount a car in OFP the game engine displays you as a driver. It would not do that if there weren't a driver proxy in the car model.
Human models have a number of proxies: one for the rifle, one for RPGs, LAWs etc., one for the binocular, one for the night vision glasses, one for the flag you can carry in capture the flag missions and one for the handgun (I hope I have not forgotten anything). All this is necessary to get the above mentioned items to show up on the soldier model, if used. All pre-Resistance human models are missing the handgun proxy, therefore no handgun will show up if you add it to a pre-Resistance model. As MrCrispPacket already said, you have to redo your addons with Resistance models or if you have the means to edit old OFP soldier models, you have to add the pistol proxy.