Need advice !
First let me say Please, don't waste forum time telling me about costs or small ring action, yada yada yada....its a special project and its what I want... if its doable??....
I have a 96 swede that I have been customizing and am wondering if I have enough metal to have the barrel (or part of) machined from round to octagon. If I do, 1. What is the min OD. 2.what accuracy problems might this cause?
3. Any other problems ???

Seems you're set on this.....
1. Mark the top of the barrel with a scribe and remove the barrel
2. you need to decide how many tapers you have to use.....you may use three different tapers from muzzle to chamber but you must decide.
3. Mill the muzzle taper first to no less than .550 across the flats.....mill between Hardinge "C" collet dividers.

4. Mill the balance to clean up only...by that I mean to create octagons....and no more...

reinstall the barrel and tie to a tire and fire with the strongest loads you intend to ever use. Having miced across the flats in several places (well maeked) remeasure looking for any increased size.

Fire a dozen rounds looking for signs of the barrel bulging.

If it's not then you can shoot it....but even .001 growth and the barrel is scrap.

Personally, I'd mill a new barrel for it and start with a 1.250 blank.....and two tapers.

There is no right answer to your question but if you do this you can be reasonably assured that it'll be safe to shoot.

I did this once on a 222 barrel.....and it was a helluvalotta work!!!!

Vapodog, thanks for the info. Original barrel is stepped in 3 places. I had not planned to mill the first 2 inches from the receiver. But its something to think about. Second step is .788 OD and felt that if I kept it to .700 it would be safe. Last step is .688 and I was shooting for .615 as a min (flat to flat). Not sure how it would look with a straight octogan instead of a tapered. My main concern is how would this effect accuracy (current its shooting under .75 at 100 yrds.
As far as pressures, its a small ring mauser so I don't push it.
Helluvalotta work....thats the sweet part, I have an extremely talented tool maker at work that wants to do it for me and we have the programmable equipment available. Just need permission to work on it afterhours and thats never been an issue. Safety and accuracy are!!

quote:

My main concern is how would this effect accuracy (current its shooting under .75 at 100 yrds.

There is always a risk in this....it sure won't improve the accuracy!!!!!

My concern is safety.....and I outlined a method to check for yielding.

I have no clue what the barrel is made of and hense no clue what thickness is required to be safe.....so make sure you mike the barrel and check for any deformation in the firing.

If your accuracy goes to hell you can always rebarrel it.

Using a varimill cutter will help the chatter in the middle of the barrel but likely you'll have to restrain it somehow.....I'm sure you know ways of doing this.

Get some good mill files because you'll be doing a lot of draw filing.

You will need a minimum of .070 for stock removal to get the barrel down to octagon so I think you have plenty of barrel to work with. For example at the .788 you will end up about .715-.720 flat to flat. I just drew it in autocad and with .788 roun you would end up at .728 flat to flat if everything is perfect. It will be about the same on the .688 portion. Why not do round to octagon to round. If the barrel happens to distort in the middle from the machine work you will still have the end of it to give the bullet a good straight portion to exit from

On the old shooters forum there was a gunsmith in Pa. who machined the military bbl. to a partial oct. profile for his customers. I don't have any contact info but maybe someone on this forum might remember.
Bob

I've bought some M96 parts from a guy in Maryland - KEBCO - or something to that effect who made reference to someone in PA doing this. Same guy I suspect.

White Rock Tool & Die (guy rent Chamber reemers) has made 96 barrels into full Octagon barrel. His phone number is 816-454-0478, his name is Keith Rice.

Thanks for all the info. I had thought about the octagon to round because several of the older muzzle loaders barrels are that way. Nick, like you, we laid it out on autocad and the .788 (mid portion of the barrel) was a definate go. The last step left .002 still round, but the .600 is a minimum on new 22 inch sporter barrels (tapered) listed in Brownells and on other web sites so I am a little hesitant to push that far on a 24" straight barrel. Part of the reason for wanting to do this is that there are several nicks in the last part of the barrel that will be tough to eliminate. Weight reduction is another and something different is the last. Rifle will eventually end up in my Granddaughters hands, nuff said.

Roger, thanks for the phone number, I will try him this weekend