Q&A for How to Make a Gun Barrel

It depends on the type and caliber of the weapon. The The Sporting Arms and Ammunition Manufacturers' Institute (SAAMI) has standardized dimensions for bullet casings and chambers to ensure safe interchangeability of rounds from one manufacturer to the next. For muzzleloading firearms, the diameter is typically the same as the barrel.

Forge a billet to the length that is needed. The barrel will need to be perfectly square. Then, twist the square billet. Make sure that it's 1-4 inches wider than it needs to be. Then, cool grind to your desired shape, heat treat, and etch.

The Idahoan says yes, but admits he was trying to make a pistol barrel using simple tools, as shown by the roughness of the finished product.

First, find a tube that fits into the barrel. Next, get a long drill rod and cut measured grooves into the barrel. If you're having difficulty, go to a blacksmith instead.

You would need a forge and blacksmithing experience.

Titanium has a melting point of 1668 degrees C, but tungsten can withstand more. However, tungsten also has greatly reduced strength at those temperatures.

Yes, shotgun shells generally don't generate much pressure. At least birdshot 12 gauge 2 3/4 inch shells can be withstood in PVC piping less than half an inch more thick than the shell itself (still wider than the rim).

Use a drill press to drill out a piece of round rod (clamp really good, start small, work your way up the sizes, go slow, be careful, use a lot of lube/oil, use quality bits), use a reamer to finish the bore, make a rifling button, push down the bore, once rifled make or buy a reamer to drill the chamber, then crown the end of the barrel. It would be the cheapest and easiest way. There's a way now to use electricity to make barrels that anyone can do, you might want to look into it.