Rifling vs Lathe Work

hawk18

In a previous post, about fluting an AR barrel, the comments led me to believe it was a bad idea to do lathe/mill work on a finnished barrel. And I thought that made sense. Now, MHS makes reference to it being OK for cut rifling and hammer forge rifling. So, now I'm not so sure.

I need an expert too straighten me out!

Hawk

tennmike

Here's an article that goes into the steps of barrel making that should answer some of your questions.

http://www.firearmsid.com/feature%20articles/rifledbarrelmanuf/barrelmanufacture.htm

Removing material from a barrel that has been through the entire process can set up stresses in the barrel. The stresses can cause the barrel to warp slightly requiring straightening. These stresses must be relieved if significant material is removed from the barrel. Taking a bull barrel and removing the amount of material required to flute the barrel exterior will require stress relieving and possible straightening.

woodsrunner

Mike, not sure that I understand what "fluting" a barrel means.....and probably don't even need to know, but: are we talking about the same thing as "swamping" a barrel for balance and better sighting ability?

breamfisher

Fluting is cutting grooves in the outside of the barrel, supposedly for cooling but really it's more for weight reduction and looks from what I've read.

woodsrunner

Now I understand. Similar to "swamping" as far as weight reduction goes, but done totally different. Thanks, Bream!

tennmike

Thanks for the picture, Earl. I'm lazy today. :tooth: Cutting straight flutes in a barrel is bad enough, but those spiral jobs, and some of the cross check patterns are worse as far as releasing stresses in the barrel goes. Anyway, stress relieving the barrels during the manufacturing process is an important step; just as important as the hardening and tempering steps.

Without going into a lot of mind numbing detail, barrel steels are NOT the same consistency throughout the barrel. Barrel steel is a mixture of different metals like a cake is a different mixture of ingredients. There will be hard spots and softer spots along it's length. They are minor differences, but they are there and cause stresses in the metal. That's why it's important to relieve any internal stresses to make the barrel 'relaxed' so it behaves the same throughout it's length. Any machining done to a piece of metal relaxes some stress points and sets up stress in others.

Teach

I had this discussion with one of the country's best muzzleloader barrel makers, Ed Rayl of Gassaway West Virginia. Occasionally, he will get a batch of steel stock that just won't machine accurately due to alloy variation and hard/soft spots he encounters during the machining process. Ed doesn't do fluting, but he offers such things as the "swamping" process on an octagon barrel, where the barrel has a curved shape in the octagon flats for weight and balance purposes- - - -thinner in the middle than at both ends. He also does various round/octagon shapes. Occasionally, Ed has been known to reject an entire shipment of barrel steel because of machinability concerns, and I'll bet another barrel maker with less-strict specifications just might buy it.

If someone attempts to do a major reshape of the contour of a barrel that's already been finish-machined and stress-relieved after the rifling process is done, I don't see much of a possibility of a good outcome.
Jerry

hawk18

Thanks again guys. I had read that article, or one similar, and gathered that re-profiling was something you couldn't do with reliable results. Thanks for the "post operative support".

Hawk

snake284-1

While a cut rifle barrel has less stress in it due to the way it was rifled, I think even cut rifled will be stressed by major removal of metal. When I was shopping for a barrel for my .250 Savage, I spoke with a tech rep at Shilen. They are totally against any flutting. Maybe that's because a Shilen barrel is button cut.

Linefinder

Here's a way to get a "cool" look and actually do enough good to help cool the barrel a bit....Scooter did it with one of his rifles and the end result was pretty neat.....

He left the nylon shipping net on the barrel, then had it bead blasted. Looked like a diamond snake-skin pattern. Imparts no stress to the barrel, either.

Mike

Teach

Hmmmm- - - - - -I've got a couple of takeoff barrels stashed away with those shipping sleeves on them. I just might do a mirror polish on one of the project barrels I'm working on, slip a sleeve over it, do a beadblast job, and then blue it. Thanks for the tip!
Jerry

SirGeorgeKillian

That's cool as all get out!

snake284-1

Yeah, that sounds really neat. I have three aftermarket barrels, one moly and two stainless that are all bead blasted. The Chrome Moly barrel is blued and the stainless ones are in the white, but the bead blasting makes them all look really good. And I hear tell it cools them faster than fluting without the problems.