For the next few days, all Adrian did was fail at making a simple brass shell.

It was annoying as hell. Still, he didn’t let the crafting grind take over his day completely. He always saved at least three hours to hang out with Aria.

Whenever the she got back from Claire’s training sessions looking like a sweaty mess, he just stopped working.

He cooked her favorite meals, listened to her stories about the sweaty uncles who cheered for her, listened to her complain about the heavy wooden swords, and spent time teaching her the basics of mana engineering.

These three hours kept his mind completely fresh. It stopped him from burning out in the underground room.

The daily routine continued and days turned into weeks.

By the time Adrian finally held a successful product, three entire weeks had passed.

He stood in the dungeon and held a single brass casing up to the light.

It looked absolutely perfect. It shined exactly like the modern bullet casings he had seen on Earth.

’Finally.’ Adrian thought, letting out a massive breath.

Now it was time to make the actual projectile. He needed the piece of metal that would fly out of the barrel when the gunpowder burned up.

This took another massive chunk of time.

Adrian experimented with different base metals and alloys that the dungeon had on record. He tried pure brass, pure bronze, copper and various mixtures of everything he thought could work.

He created multiple variations of them, adjusting the weight and and shape of each one.

This testing phase took him another four days.

Once he had all the pieces, he happily walked over to his assembly table.

He didn’t have to pack the bullets by hand. He used his authority as the Dungeon Master to automate the process.

He commanded the dungeon linked though the system to pour the exact right quantity of gunpowder into the brass casings. Then, the dungeon perfectly seated the metal projectiles into the top, sealing them tight.

He made sure to create a test batch for every single variable.

He had a handful of bullets for every type of tree charcoal. He also had those bullets topped with every single variation of brass and bronze projectiles.

He didn’t know which charcoal would burn the cleanest or which metal would fly the straightest. He needed hard data.

Adrian gathered his large pile of experimental ammunition and walked deeper into the secret room.

He approached a solid stone wall. With a single thought, he commanded the dungeon to open a gap in the stone. He stepped through into a long, empty tunnel and closed the wall right behind him.

This was his personal firing range.

He spawned a thick wooden target at the far end of the tunnel.

Then, he spawned his bolt action rifle. He had put in a lot of work into this since he got bored pretty easily while he worked on the cartridge and the bullet itself. It’s barrel was thicker, had rifling, and the bolt action mechanism itself was in a working condition.

Compared to testing out different materials and metals for the bullets, this took considerably less time.

He didn’t hold the gun himself. He wasn’t stupid enough to test experimental explosives right next to his own face.

He walked up to the side wall and pressed the rifle against the stone. He willed the dungeon to mold the rock around the weapon. The stone shifted and hardened, fusing perfectly with the wooden stock while leaving the rest of the weapon free.

The rifle was now completely fixed in place. It couldn’t move or kick back from the recoil.

After shoving a bullet into the chamber, Adrian backed away.

He moved to the far corner of the room and hid behind a stone pillar he made recently just in case the gun blew up.

Poking his head out, he pushed some mana forward.

He grabbed the trigger with a basic telekinesis spell and pulled it.

A loud bang went off inside the tunnel.

Fire and smoke shot out the front of the barrel. At the other end of the room, pieces of the wooden target chipped off and hit the floor.

Adrian grinned. It actually worked.

He pulled up the dungeon system screen. Since the rifle and the target were both being used inside the dungeon, the systemcould easily track the physical data of the interaction as long as the two of them were linked, which wasn’t really a problem.

A blue window popped up in front of him.

It listed the maximum velocity of the projectile. It calculated the maximum effective range based on the bullet’s drop. It even showed a microscopic durability report, detailing exactly how much damage the explosion did to the inside of the barrel.

Since adrian had added spiral rifling to the inside of the barrel while he was making the bullets. The system reported exactly how much the bullet gripped those grooves and how fast it was spinning.

’This is incredible.’ Adrian thought as he read the numbers.

He didn’t stop there. He used telekinesis to work the rifle’s lever, ejecting the spent brass casing. He loaded the next experimental bullet into the chamber and took cover again.

He fired the gun over and over.

The underground tunnel smelled like heavy sulfur and burnt wood. The pile of empty brass casings on the floor slowly grew larger.

Adrian tested every single bullet. He tested the oak charcoal powder. He tested the pine charcoal powder. He tested the bronze tips, brass tips, copper tips and the other alloys and metals.

He recorded every single result using the system’s tracking feature. He compiled a massive list of bullet performances, comparing speed, range, and barrel damage inside a book.

It took hours to get through the entire batch.

When the final shot rang out, Adrian wiped the sweat from his forehead. He opened the book and looked through the results.

"Dungeon, take this book and compile the list for me. I’ll need the results to be sorted so I can make a proper choice." he said and the book disappeared from his hand.

The screen appeared in front of him with the list and he scrolled past all the failures, the slow bullets, and the rounds that caused too much friction inside the barrel.

"Make separate copies of the list and sort them at a descending order of maximum projectile distance, damage taken by projectile, damage taken by the rifle itself and damage that the bullet can deal."