Okay, look, if you already know everything and just want to see the spreadsheet, here is the link. It was far too large to try and stick all the information within a single table in this guide or take a screen shot of it and paste it in here, so it's on Google Sheets. I tried to set it up to keep panes frozen, but it doesn't look like it wants to work on a shared file, so if you know how to fix that, let me know. Freezing panes should be working, looks like it was a published file issue.

https://docs.google.com/spreadsheets/d/1vUTNGAC8VTqsA0BnFe7mrbMz6JMeR3XH9Z5J6fKnojs/edit?usp=sharing

Alright, now that you are back from looking at that monstrosity, I can break it down into smaller pieces and try to explain some of the fusion process.

Weapon fusion cores are created by taking a weapon and merging a secondary weapon with it. This destroys the secondary weapon in the process, but what you get out of it is a "Core" that enhances the stats of the primary weapon in some way.

These cores are another way to augment your weapons like the modules do, BUT unlike modules you cannot double stack them like putting an Armor piercing IV and an Armor piercing III on the same weapon to get a stacking armor piercing from both modules.

While this kind of sucks, the way to upgrade Cores is a bit simpler than having to craft and combine 8 level I modules to create a single level IV module. Now, I say simpler, but it can be hassle sometimes with the RNG nature of getting the core you want, but hopefully some of the information I am writing down will be of some use.

This is also a good point to mention that if you happen to get a core that you don't want you can drag it out and trash it and try your luck with the RNG again by sacrificing another weapon.

Now, I have all initial core offerings documenting back in that previous spreadsheet, but in order to explain it a little bet better we need to segue into...

Why do weapon types matter?

Well, the whole fusion system seems to be based off of these weapon types. Just like only certain modules can be equipped to certain weapon types, only certain fusion cores can be generated or equipped by certain weapon types.

Now Common sense will prevail here and the majority of the fusion cores makes sense, like, the ammo cores would come from weapons with a large ammo capacity and you would be right. HOWEVER the chart I generated is hours of frustration because why would I settle for a High capacity magazine core when the Super Large Capacity drum magazine core is so much better? How come I cant get a kinetic splitter core A or B on my service rifle A3? Well, I'll tell you why, it's because not all cores work on all weapons, and all weapons are not created equal.

Kinetic - Over 50% of the weapons fall into the kinetic category, but this is what I'm calling a super-type and it has several sub-types that fall under it. There is However a single weapon that is purely kinetic that falls into this category and that is the AMAZING Service Rifle A3 and its subsequent upgrades.

Guide Rail - All guide rail weapons are kinetic, making it a sub-type. Excluding the A3 family, guide rail includes all rifles and submachine guns, even the electromagnetic and water bullet gun. There is also one sniper which includes the guide rail sub-type and that is the Rapid Firing Gun which is currently the only 3 type weapon gun in the game. NOTE* while going through and creating my spreadsheet I noticed there are 2 pairs of submachine guns that have the same names but different stats.

Sniper - Once again, all sniper weapons are kinetic, making this a sub-type with the only outlier being the Rapid Firing Gun previously mentioned.

Machine Gun - All machine guns are kinetic as well, making this a simple sub-type.

Spreadshot - There is a decent amount of spreadshot gun variety. This is a sub-type with all but the howitzer and its upgrade being the kinetic super-type.

Explosive - There are only two pure super-type explosive weapons (and their upgrades) with the third being the howitzer, which is an explosive spreadshot.

Sprayer - All sprayer weapons are self contained

Ray - All ray weapons are self contained.

Arc - All arc weapons are self contained.

So.. now that you take a look at the weapons we can see that their types affect what modules can be equipped and that affects which cores can as well. For example, only the Guide rail weapons can equip the grenade attachment module, so it makes sense that only they would be the ones to be able to use the mounted grenade core.

Clear as mud right? Well there is more!

Lets show an example of a basic weapon merging.



I've got my weapon that I want to enhance in the upper left, my sacrificial merging weapon in the upper right, and my initial core offerings on the bottom with their RNG percentages.

Lets merge them aaaaaaaaaannnnd!



I got one of the reloading cores, nice right? Now... before we look at the next picture go back up. Remember that each core had a 25% chance? So... makes sense to think that if we buy another merging slot and stick another Identical rifle in to be merged the next offerings would be 3 choices at 33.33% chance each right?

Well, lets take a look!



Suprise!

Here you can see that there is a hidden chance to upgrade that core to level II that wasn't initially offered to you. Now lets say we really wanted that level II upgrade instead of the other cores. Lets take a step back and NOT buy another merging slot and do the same thing again with the same rifle.



Look at that! 100% chance! You can force certain core upgrades by limiting your slots. When you are all done here you can go take another look and see that maybe sacrificing your cheaper weapons to RNG to get an initial lower level core can guarantee you a high level core that you want by sacrificing a higher weapon later on while avoiding the RNG nature and potentially losing out on tons of money trying to get the right Core

Now here is where you might be thinking Ilikerice... that seemed pretty easy, maybe all the cores have a hidden chance to keep upgrading to max? Well, some do go up a level, others stop, others do weird stuff. Lets look at another example below.



Looks like some weapons go full hog and will offer you tons when you pass the initial cores and dive into looking at hidden cores. Now, my spread sheet is not complete on hidden cores, because I am exhausted just doing the normal initial ones, but I will try to keep it updated whenever I'm bored at work or whenever I play more and get back into the groove of the game.

Look at my sheet, it will give you specifics, but if you don't here are the basics.

Kinetic / Guide rail weapons will give out reload and kinetic based cores.

Sniper weapons give crit, dmg, and crit dmg. They also give the delayed fuse core for explosives.

MGs give Ammo cores, bipod and rapid ray firing cores.

Spreadshots provide splitter cores, ray trident cores and some arc cores and spread constriction.

Sprayers seem to offer a little of everything to each weapon type following spreadshots splitting.

Rays gives some ray centric cores and offers a couple other cores to other weapon types.

Arcs gives some arc centric cores and offers a couple other cores to other weapon types. (Except the healing gun, it kinda sucks)

Thank you for reading, hope it helps!

1/25/24
Minor grammar corrections.
Verified and updated the spreadsheet for the hidden cores for the following weapons.

• Service Rifle A3 - and upgrades
  
• Antique Rifle - and upgrades
  
• Antique Rifle A1 - and upgrades
  
• Armor-Piercing Rifle - and upgrades
  
• Service Rifle - and upgrades

2/1/24
Verified and updated the spreadsheet for the hidden cores for the following weapons.

• Service Rifle B1 - and Upgrades
  
• Service Rifle B2 - and Upgrades
  
• Submachine Gun - and Upgrades
  
• Submachine Gun A2 - and Upgrades
  
• Submachine Gun B2 - and Upgrades

Started to collect data on the Workshop HEWS weapon, added at bottom of spreadsheet.

3/1/24
Haven't played in a while since I gave away my steam deck.
Verified and updated the spreadsheet for the hidden cores for the following weapons.

• Rapid-Firing Gun - and Upgrades
  
• Electromagnetic Sniper Rifle - and Upgrades
  
• Heavy Sniper - and Upgrades
  
• Light Sniper - and Upgrades

3/26/24
While testing the machine gun cores I noticed that I missed some Chamber Pressure Overload Core and Super Large- Capacity Drum Magazine Core that were initial core offerings. I apologize, I am not data mining these results they are from in-game tests and I must have missed them.
Verified and updated the spreadsheet for the hidden cores for the following weapons.

• Heavy Machine Gun - and Upgrades
  
• Vulcan Cannon - and Upgrades
  
• Light Machine Gun - and Upgrades

I have now tested 66/123 ranged weapons in the game and am over 50% complete with finding all of the hidden cores available.

5/25/24
Been doing a lot of traveling for work, but I saw the update so I'm trying to get back into it.
Verified and updated the spreadsheet for the hidden cores for the following weapons.

• Standard Pistol - and Upgrades (New Kinetic Sniper)
  
• Gauss Sniper Rifle (New Kinetic Sniper)
  
• Howitzer - and Upgrades
  
• Cannon - and Upgrades
  
• Rapid grenade - and Upgrades
  
• Miniature Hand Cannon - and Upgrades (New Explosive) Think this is bugged, gives no cores.
  
• Magnetic Railgun (Sounds like a Sniper, but it's a new Explosive)
  
• Lava Spray (New Spraying) Added but not complete
  
• Purgatory Ray (New Ray)
  
• Thor Burning Cannon (New Arc)

I'm going to do the spreadshots last, because they have the largest core offerings.

5/26/24
Verified and updated the spreadsheet for the hidden cores for the following weapons.

• Flame Thrower - and Upgrades
  
• Frost Spray - And Upgrades
  
• Oil Spray Gun - and Upgrades
  
• Water Spray Gun - and Upgrades
  
• Lava Spray

6/18/24
Saw the Update, so I took another look at the upgrade slots for each weapon. Unless I had some wrong before It looks like a couple have changed.

• Antique Rifle A1 - 4/6 -> 4/3
  
• Antique Rifle A1S - 5/4 -> 6/5
  
• Armor-Piercing Rifle B1 - 9/3 -> 9/5
  
• Submachine Gun A2 upgrades in game names have changed from A2 - A2S - A2S - A2S12 to A2 - A2S - A2S1 - A2S12
  
• Submachine Gun upgrades still incorrectly named in game as Submachine Gun - S5 - S5M - S5M - S5M10, the 2nd S5M upgrade name should probably be S5M1

8/11/24
Apparently publishing the sheets document was the thing not causing the panes to freeze so I swapped out the spreadsheet with a shared document instead.
Verified and updated the spreadsheet for the hidden cores for the following weapons.

• Shotgun - and Upgrades
  
• Pump-Action Shotgun - And Upgrades
  
• Double-Barreled Shotgun - and Upgrades
  
• Buckshot - and Upgrades
  
• Rapid Spreadshot - and Upgrades

Only Ray, Arc, and workshop weapons remain for hidden cores.