First off this is very much a work in progress. So use as you like, but if something doesn't really work let me know.
Second the why I made this. I didn't like buying a shotgun at level 1 and not having another avialable until so much later. With all the tech available and skill it seems really odd to me that there is no way to actually improve an item. I imagine that Paizo will eventually get to this but for the time being I figure this should help.
Finally as I mentioned its still not finished. I have not put in a DC for skill check because I am uncertain what it should be. I am thinking the (new item level x 1.5) + 10.
Now I apologize for taking so long but here it is: Upgrading Weapons (for fun and profit).
I like the concept. I think 4 upgrades might be too many, since the cost per upgrade isn't scaling and the points gained per upgrade increases (at least as I am reading it).
The range/radius of the weapon templates (Line/Cone/Burst) need to be defined and are vastly under costed. In truth they should probably be limited to improving weapons with those properties already as they tend to have Reduced Damage/Increase Ammo Consumption/Unwieldy built in.
The cost is supposed to scale but I see how I failed to word it correctly. Say I am upgrading an azimuth laser pistol. Upgrading to level 2 costs 350 credits. Upgrading to level 3 is supposed to cost 700 credits. Upgrading to level 4 will cost 1,400 credits. The final upgrade to level 5 will be 2800 credits. This means a fully upgraded azimuth laser pistol is going to cost you about 5,600 credits. You will get 14 points total for upgrading.
Line, and burst are already explained in the base rules, I don't have to repeat that in the document, but I can put in a link so there is no confusion. Please note if you do upgrade to one of those properties you will only be getting that one property. But I do agree that the range for a burst upgrade needs reduced; a level 2 azimuth laser pistol shouldn't be producing an 80 from cone. Probably adding the burst ability should quarter the normal range of the weapons and probably the same with the line.
I have updated the document to reflect these changes and added bit about upgrading ammunition.
Combination Weapons have been added to the document.
Barring feedback from other people I am likely done with my upgrading weapons document. The only thing I have left is to adjust the damage progression chart to account for the different dice in Starfinder. Next will be a rebuild/upgrade document for armors.
I really hate how starfinder armors are literally just "spend money get another +X" my intent will be to have different armors be focused on different areas and include a section on upgrading armors much like this does for weapons.
In regards to combi weapons, I had a notion of how they might exist in the setting without everyone simply buying one of them.
So lets say I have a combigun particle beamer that does 'acid' damage due to molecular disruption, cold damage not through streamed gasses but due to a stasis effect that slows down the molecules of the stuff it hits, 'freezing' it, and then a general plasma damage setting.
The way I figured to balance it would be it has the cost of a normal tier gun, but the functional damage in either of its settings of a weapon around 5 levels/tiers less. So if you wanted an acid gun, you'd be potentially better off just buying an acid gun, or frost or plasma weapon. In this regard you pay for convenience and adaptability but lose out on the default specificity/focus of a general weapon.
At the same time, having such a combigun would be cheaper than having to pay for 3 separate weapons.
As it stands, yeah for Armor its kinda ridiculous. Half a million more creds just for another +2? when you get to the upper end of the chart.
Well until I do an actual weapon building system I went along the lines of existing underbarrel weapons.
I do need to add a line about a single combo limit. I don't think there is any cheese to be had but for aesthetic reasons I don't think a 3 in 1 is going to fly well.
To some extent I understand if why the last couple of +1~2 costs so much (law of diminishing returns), but even so the armors are simply too much alike for there to be reason for.
My idea for custom or upgraded weapons was more to give them something that sets them apart from similar weapons. For example I think my party is about to find a choked utility scattergun that changes the cone to be longer and narrower. Power armor with a cruising mode for lower consumption, requiring a move action to be combat ready. That kind of thing.
It's not something I intend to create a system for, and more invent them as they come up.