push button rifling

[john.k]

Some 40 years ago,I went to see button rifling ,first in Australia,he said......and the button was both pulled and pushed being brazed to rods at both ends.The tubes were also put in a furnace at 400degC,"to set the lubricant"...which I assumed to be some type of glass.....that being used in some high pressure steel drawing operations at the time........But button rifling of 22 barrels and liners is a lot older,back to pre 1900 .it was called swaging.........as to broaching..its well known the P14/M17 barrels were broached,and Ive seen a reference to the first broach being 3x10 foot sections,and costing $25,000..in 1916.The broached barrels were also notorious for cuts and scratches in the grooves.But the process did enable some 3 1/2 million barrels to be made between mid 1916 and early 1918.

 

[partsproduction]

But the process did enable some 3 1/2 million barrels to be made between mid 1916 and early 1918.

Which makes one wonder how many barrels they got between broach sharpenings. Obviously they can only sharpen a certain number of times, for key broaches I think it's 3 times perhaps?
My Karl Gustav Swedish Mauser came with a brass disk that tells the bore diameter among other things, apparently they came to the troops with some slight variety of bore diameter. I wonder if the Mauser barrels were broached?

 

[john.k]

The broaches had a few rows of sizing/finishing cutters, and as each cutting tooth was ground ,it became a little smaller,and the number of rows of sizing teeth reduced......but this was a fortuitous happening,because when .303" production ended,the undersize broaches were then good as new for .300 " production....Mausers were cut rifled until early WW2,then hammer forging was developed about 1940,and barrel production time reduced to a few minutes,with no wear on tooling.

 

[msalm]

Hart barrels pushes their buttons. Not sure how they specifically do it, but a barrel maker once told me one way. For the push rod 'guide', picture a drilled rifle barrel blank with a 90 degree slice cut out of it lengthwise. This is the guide as the hole through will capture the push rod. The pusher is machined to fit this 'keyway' of sorts and is able to push the button through without bending the push rod.

 

[HallBilly]

Hello.
I've made several 12" long barrels, but only for subsonic (Less stress, so hopefully they won't blow up ??)
My favourite is 9X19 Luger. I like quiet 22's so logically four times more projectile at the same speed must be good, right ?
I had a 223 bolt action that refused to shoot predictably straight, now there is only a few thou' difference between their respective rim diameters and that was enough to get me started.
Why 12" long ? In New Zealand rifles must not be less than 30" long and a 12" barrel meets that, also remember it's only subsonic pistol ammo.
I drilled and reamed 304SS to suitable diameter (Don't get all upset ! It's only subsonic so 304 is good enough).
Bought a Ukrainian button and pushed it down the bore using old 8.5mm drill shanks, I'm sure silver steel will be too soft.
It came out beautifully, the rifling is deep and defined, the twist is correct.
Didn't have a chamber reamer available, it's only 3/4" deep so bored it.
Receiver was designed for mid length 223, so had to mill chunks out of it to help eject the short pistol cases.
Mounted a 12" cheapy Chinese (Solvent filter) on the end, I can't buy the material for less than finished Chinese item.
168grain ammo makes some noise (Hollywood has lied to us) but quite acceptable.
Due to the locking lugs I haven't figured out how to fit a magazine and also hand feed is good enough.
This is a good fun, stealthy, 100yard (Max) rifle.

Then I made a 45-70 barrel and fitted to a 100 year old Winchester made British P14 (Don't worry I'm not an animal, the original barrel was rubbish).
Ukrainian button generated a very slow twist, but I still went ahead with finishing and mounting it.
Yes some subsonic projectiles do go sideways, but at 50 yards you get a combination of round and rectangular hole within a 3" circle (Good enough).
Then I made my own button out of an old HS tap and ground straight grooves at an exaggerated angle.
It worked and proved the concept is sound, though not good enough to use.
Got another piece of steel sitting on the bench and hope to find time to get started on the next barrel.

I'm quite happy to provide extra info if someone is interested, but be warned, for every successful barrel, you leave a pile of failures behind you.
Wonky holes, scratchy bores and wrong twist rates could be waiting for you.
Seriously it's probably cheaper to buy a finished blank barrel.

It's been good fun and I've had to experiment and develop technics to get this far, not bad for a grumpy old toolmaker.

 

[partsproduction]

Yeah the pre rifling bore size and finish are critical. I've already forgotten the formula for bore size to get full riflings. And yes, I also got some bad tries, because the bore wasn't right.

 

[john.k]

Its actually easier to cut rifle a barrel,as no dimension is critical ...you simply pack up the cutter until the depth is good.........incidentally,there is a famous series of total fails of button rifling on 45/70 Marlins made by Remington pre recent bankruptcy..........and backed by the fact that Remington refused to warranty the fails ....."they passed the inspection robot,so they must be good enough"

 

[MilGunsmith]

We had a bunch of button rifled .270 barrel blanks from a new to us manufacturer, that came in with .273" groove diameters instead of .277". The bore was correct at .270" for the chambering reamer pilot, needless to say test shots exhibited high pressures. Sent all of them back.

 

[HallBilly]

Yeah the pre rifling bore size and finish are critical. I've already forgotten the formula for bore size to get full riflings. And yes, I also got some bad tries, because the bore wasn't right.

Absolutely. With the last few barrels I've reamed to within a few thou' of finished size and then pushed a polished sizing button down. A little bit of grinding paste polishing and Bobs your uncle.
As an apprentice I worked in a Nut and Bolt factory, we made all our own cylindrical dies to support bolt shanks during forging.
So we had a lovely bore honing machine that would have easily finish a parallel 2 foot long hole all the way down to 1/4" dia.
Now I wish I had access to it ?!?!?! Just another missed opportunity ?!?!?!

 

[john.k]

For a one off or a few barrels,I would think the old process of spill boring would be useful for sizing a bore to suit a button.