helical dented pipe for rifling a barrel

[ROMEOHOTEL]

Imagine a straight pipe which by means of a narrow roller set oblique to the pipe's longitudinal axis a continuous helical dent is made to spiral along the pipe's length. The roller rides on the outside pipe diameter while the pipe is rotated. The dent is transferred to the inner wall. By means of indexing, a series of such dents are made to the pipe. Thus, the lands are made and the interstitial spaces become the grooves.

That pipe is then sleeved inside a thicker walled straight pipe. The assembly is then quenched. Voila, a rifled barrel.

This idea occurred to me after I watched a video on Viktor Schauberger's work. Actually, the genesis is the E. Neumann spiral.

[ROMEOHOTEL]

A picture of several pipes with one helical dent each.

[Dark Hunt]

It's easier to pull a rifled button through a thick walled tube,

[Walking Fire]

I have seen the Alfred E. Neuman Spiral......

[M1NM]

It's easier to pull a rifled button through a thick walled tube,

Your method would not leave sharp rifling in the inside'
Button rifling is sharp but tool chatter or poor chip clearing and cause defects. Hammer forging the rifling and barrel is best.

https://www.youtube.com/watch?v=oALJDh43K3I