what kind of finish ?

[GGaskill]

I can't grip it in the chuck securely without marking it.

Turn a bullnose center in the chuck and use a dog on the barrel to turn it between centers.  Make a simple clamp dog like this one.

[and7barton]

I can't grip it in the chuck securely without marking it.

Turn a bullnose center in the chuck and use a dog on the barrel to turn it between centers.  Make a simple clamp dog like this one.

Thanks for that info.
Richard

[GGaskill]

Actually, thinking a little more about it, do you already have a center drilled hole you were going to cover with the welded on cascable?  If so, use that, then weld on the cascable.

[and7barton]

Actually, thinking a little more about it, do you already have a center drilled hole you were going to cover with the welded on cascable?  If so, use that, then weld on the cascable.

The cascable hasn't been welded on yet, but there's no hole on the rear of the breech end, the barrel was bored leaving around 4 inches of solid steel behind it. but I could drill a short locating hole. Thanks for that hint.

[dominick]

I use a 4-1/2" disc sander [36 grit] while spinning the piece in the lathe to remove millscale.  Then run a belt sander with finer [120] grit paper to align the sanding grain pattern around the tube. 
I machine 'Hot Roll Steel' millscale with the lathe.  It is usually very difficult to remove by sanding.

[Frank46]

There is a chemical process or two part system thats sold under the name "tool black". Leaves a black oxide finish similar to that found on pin wrenches. One part is what I believe is actually the tool blackening solution and the other is the preservative. I used to get a british machinists magazine and I believe its sold by G.L.R
Distributors LTD unit C1 Geddings Road Hoddesdon Herts EN11 ONT Web Site www.glrmodelsupplies.com
Tel 01992 470098. They list it as KOOLBLACK good for steel, cast iron and iron. Simple immersion at room temp, permanent heavy duty blackening. The name of the magazine is model engineers workshop. Hope this helps. Frank

[and7barton]

There is a chemical process or two part system thats sold under the name "tool black". Leaves a black oxide finish similar to that found on pin wrenches. One part is what I believe is actually the tool blackening solution and the other is the preservative. I used to get a british machinists magazine and I believe its sold by G.L.R
Distributors LTD unit C1 Geddings Road Hoddesdon Herts EN11 ONT Web Site www.glrmodelsupplies.com
Tel 01992 470098. They list it as KOOLBLACK good for steel, cast iron and iron. Simple immersion at room temp, permanent heavy duty blackening. The name of the magazine is model engineers workshop. Hope this helps. Frank

I know the store....a really marvellous aladdin's cave of stuff.
I've bought stuff off them before.