this idea for a progression tree could be far better than what we currently have; progression tree for each campaign.
with this new progression tree, it will be a single tree of weaponry that you can research regardless of what campaign you play as, meaning you can play any campaign, and still be able to grind xp for whatever weapon you’ve selected for research.
now there will be a issue where people would grind XP for weaponry that obviously will not be available for the campaign they play in, thats not a big issue, the weapon can still be unlocked/researched, but it will not be buyable or obtainable in that certain campaign. for example the stg44 can be researched by playing in tunisia or any other campaign, but you cannot obtain/use it until you switch to the appropriate campaign, such as normandy or berlin
in the following graph, i made a crude progression tree for german weaponry (i possibly left some stuff out, forgive me on that, and i added some weapons that i personally think should be added)
in some cases like assault rifles, i added multiple, basically same variants of the german stg lineup, but they will be used for exclusivly various soldier classes (mp43/1 for assaulters, stg44 for riflemen, mp43 for AT gunners/engineers, mp44 for the rest)
the idea is, you will progress from the top of the graph (the oldest dated weapons), right up to the latest weapons, in some cases it will have to be opposite due to obvious reasons.
starter weapons will not need to be researched, they will be already available, and unlike the current system they will be buyable, and wont be classified (gewehr 33/40, kar98k, kriegsmodell)