octagon vs. oct/rnd in larger caliber "accuracy"

[Salkehatchie]

Given two barrels:  1.) octagon to round, .58 caliber rifled, 44"  and 2.)  full swamped octagon, 42", .58 caliber rifled.

Which one will be more accurate?  Now, me thinks that conventional wisdom dicates the full octagon rather than the octagon to round.  Reason being more weight at the end of the full octagon barrel.

Yet....when I look at total barrel weight, there just ain't a whole lot of difference!  Colerain has them @ 4.36 and 4.55 pounds respectively.  I mean IF weight at muzzle makes a difference ["barrel whip"] there can be no great difference between the two.  Mere ounces, maybe.  Maybe that does make a difference.

Any experience with this issue?

Thanks, as always.

[Dphariss]

If the steel in each is properly normalized there will likely be no difference in a cut rifled barrel.
Button rifled barrels that are 1/2 octagonal are often tent stakes. Again care in annealing can change this but I don't trust them.

Dan

[Salkehatchie]

Button rifled barrels Dan?  Got so much to learn.

Thanks.

[Levy]

It's the corners of the octagonal barrel that give it more rigidity.  When you turn then off on a lathe, it makes the barrel less rigid.

James Levy

[Daryl]

The only place I can see for buttoning a barrel would be a large bore, slow twist in a heavy octagonal barrel.  With around 90" to 100" of twist and .004" deep, a buttoned barrel would be OK for a patched round ball.  i could live with that, I'm sure - for anything else, make it cut rifled.

[Dphariss]

It's the corners of the octagonal barrel that give it more rigidity.  When you turn then off on a lathe, it makes the barrel less rigid.

James Levy

Ah yes, but some (many?) claim that round barrels are more accurate.
There is no absolute answer to many such things.

Dan

[Pete G.]

Depends on whether you're talking practical accuracy of match winning accuracy. It seems to me that if its a matter practical accuracy then whichever you like better. I've noticed that quite often we tend to shoot better with our favorite guns. Perhaps it is merely a function of shooting our favorites more often, nevertheless it still seems to be a factor.

[Paddlefoot]

For Salkahatchie. The button rifled barrel is rifled by pulling a "button" that has the profile of the rifling machined into it through a slightly undersized,bored blank. It works well if there is not too much profiling to be done on the outside of the blank. Because of the stress involved in pulling the larger button through the smaller bore, many people have experienced accuracy problems if they do much machining on the outside surfaces of a button rifled barrel. This releases the stress in the metal unevenly and causes the bore dimensions to change somewhat. Mostly happens now in modern guns after fluting or some reprofiling operation. Not aware of anyone still button rifling in the ML world. I think Douglas was the last, at least in the custom barrel market. Look up Precision Shooting magazine articles for more details. They argue about the merits of barrel manufacturing constantly in there.

[Daryl]

If octagonal barrels of the same weight as round barrels were more accurate, modern bench-rest for close range (100 to 300 yards)and long range 1,000 yard)  barrels would not be round, but octagonal.

[Dan]

Boy oh boy, this subject can turn into a can of worms quicker than a politician can put his hands in your pocket on a cold day.

My opinion:  Without getting into the merits of different methods of  rifling a barrel, the essence of external barrel form is one of style preference, so far as muzzleloaders go.  If all else is equal barrel stiffness is a function of column diameter and length, and in that regard octagon barrels are lighter for a given major diameter than round barrels...sorta like fluted barrels vs. round. Only thing I'd say 'bout accuracy potential is...less machining is better than more and round barrels are easier to produce than octagon.  I don't think there is any inherent advantage between one or the other.  Mixing profiles on one barrel might not be to your advantage if high precision is the objective but that's an opinion, not sworn testimony.

Fact:  I got no more to say on the subject 'cause it can get way too deep, way too fast.

[Salkehatchie]

Wow, good bunch of postings Gentlemen.  Thank you, as always THE place to go to get info.

[Daryl]

Oh, did I forget to add In My Honest Opinion, AGAIN!!!