Ball Burnishing??

Ball burnishing simply smooth's the radial grooves from the top of the lands from the boring process creating a surface that is less likely to strip lead or jacket material creating metal fouling. The amount of metal displaced is so minute that the lands will not mushroom. I have seen boroscope pictures that comparing a regular bore to a ball burnished bore and the difference is night and day. On a regular run of the mill barrel the lands look almost like files, while a ball burnished barrel I suspect displaces metal from the high spot into the low and was done from the breech to the muzzle.

Pictures would be good. Ta

Mmmmmmm, interesting theory Mr Moose but, pray tell, exactly how does this 'transfer' or 'displacement' of metal take place in a squeezed-down area? During which time, while taking into account............ Nope. I'll leave the second part for when the answer to the first part comes in!

Please don't think that I don't enjoy and respect reasoned argument but so far........... Nope, its what used to be called sheer quackery.

I have a question! How is the ball forced through the barrel?

It will be drawn through a barrel I should imagine, liberally sprinkled with fairy dust and ju-ju paste during a full harvest moon for good measure

Quote:

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Originally Posted by 30Three

I have a question! How is the ball forced through the barrel?

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IIRC compressed air was used.

Compressed air...................!!!!!!!!! Impossible I'd say because the air would be venting forwards all the time via the 5 rifling grooves. Unless the volume/pressure of the air was soooooooooo great that it would.......... Nope, I'd say drawn through as button rifling might be today

Barrel makers who use the button-rifling process use something vaguely related, but NOT after the barrel is "finished"

After the blank is drilled and reamed, (a whisker "undersized"), they run a "button" that is essentially a polished, tungsten-carbide "rugby ball", through the barrel. This is intended to "iron out" any fuzzy bits before the rifling button passes through. The more precise the blank is before rifling, the better, and that applies to all rifling methods.

Probably more useful with stainless-steel barrels, as that stuff is weird.

Folks making hammer-forged barrels don't do it, but prefer to concentrate their efforts on producing a blank that, after a basic drill and ream,is machine-lapped to a mirror sheen internally, before it goes anywhere near the big, noisy, rotary-hammer gizmo.

And as for "ball burnishing a standard, "mil-spec" SMLE barrel. They seem to have ALL been hand lapped, as per manufacturing instructions.

Early ones were also "taper-lapped, but in a weird way. The rifling lands were deliberately lapped to form a slight taper that belled slightly outwards towards the muzzle.

Apparently the goal was to reduce the "resistance" of the lands on the bullet, in order to try to increase muzzle velocity closer to the "proper" Lee-Enfield rifles.

Probably kept a lot of skilled tradesmen "off the streets" for a while, until the Mk7 bullet came along and all bets were off. HOWEVER, I have TWO MINT Lithgow "Heavy' barrels here that display slight but measurable "belling" towards the muzzle. Did Lithgow maintain the practice across the board til the bitter end, or was this another bit of "target-rifle Voodoo"?