how does one create a round bottom Octagon barrel?

[JCKelly]

After hot rolling that 8620 bar is not very straight.
It is good practice to anneal the bar after hot rolling.
Now the steel mill has a wavy bar.
Couple of ways of getting it straight.
One is to pass it through a series of off-set rolls.
Regardless, to make a wavy bar into a straight bar it must be bent at more or less room temperature

That leaves residual stresses in it.
Machine it unevenly and it will bend.

Unless, of course, one stress relieves the straightened bar. For steel this is usually done somewhere around 1100 or 1200F.

[Don Getz]

I have been away from the forum for a while , but, I see nothing has changed......still getting a lot of wierd requests.   Over
the years we have made a lot of Harpers Ferry barrels, both 33" and 36".   If you want the bottom portion of the octagon
section of the barrel to be round, you should first make a complete octagon to round barrel barrel.  You could then remove
the "corners" on the bottom flats,  either two or four "corners".  Not sure what it would do to the side flats insofar as the
inlet into the stock goes.    My first thought was, why in the h____ would you want to do it?........Don

[Long Ears]

Welcome back Don! I've certainly missed you. We'll get some straight answers now. Bob

[JCKelly]

Steel Mill terminology.
"Cold Finished" means just exactly that. It means the final mill operation to that metal was done about room temperature. This might be pickled in acid to remove the heat treat scale. It might be centerless ground to remove scale & make that rough hot rolled bar nice and round. Or, it might be cold drawn, which means residual stresses. Everyone, including I formerly, assumes "cold finished" means cold rolled or cold drawn. Not to the steel mill.

No doubt Rayl knows what he has & treats it appropriately.

For the rest of us, I suggest that about any piece of steel you buy will have some amount of resiidual stress in it. Actual cold drawn or cold rolled steel has too much stress to machine anything decent where more is metal is taken off one side than the other. "Stress relieve" for cold rolled/cold drawn/welded steel is about 1150-1200F, about where steel becomes hot enough to just begin glowing in a room with midiocre light, e.g. my basement shop.

[Dphariss]

A couple of points...  I don't believe it's accurate to say that all modern muzzleloading barrels are made from cold drawn material.  I'm almost certain Ed Rayl uses hot rolled bar.  Rice also performs a stress relief heat treatment on their material.

I agree. "Virtually all" would be more accurate.

Dan

[Dphariss]

In short, if you take metal off one side, and the barrel looks bent, just file off same amount off the other. It will straighten out again.

There will be interior changes as well in a stressed barrel. The bore may well grow.

Dan