Thank you for your input Grumpy.
For the record, my experiences so far, limited to only .380 ACP pistol length barrels 6 to 7 1/2" lth, 1" OD, 416 stainless (Living on the Oregon coast I've come to feel an affinity for stainless over carbon steel).
The buttons are carbide, made in Germany I believe, and sold on ebay from Slovenia. I also have three other calibers coming from Russia that are high carbon steel or HHS, said to be good for 500 barrels. The tool steel buttons are much cheaper of course.
I use "Moly Z" powder, very fine flour of molybdenum Disulfate, and mix it into a thick gooy paste with Napa silver bottle never seize, which I slather all over both the ID of the blanks and the buttons. A carbide rod anchored rigidly (Press fit) to the ram of a hydraulic power press pushes down into the blanks which are threaded into a larger platen, so that there is no capability of either pushrod or blank to kick out sideways, and the blanks are free bored 1" to the button diameter so that it also is forced to drive straight.
The gent who sold me the buttons said to bore the blanks .348" (
http://mail.centurylink.net/service/home/~/Tips to 380 ACP.pdf?auth=co&loc=en_US&id=139021&part=2) but I'm getting good results starting much smaller, .336".
The real difficulty came as a surprise to me, the pressing, which I imagined would be very difficult, is easier than expected, perhaps due to the extreme attention to alignment I've been giving things. But the real difficulty is the blank's pre pressing size consistency and smoothness, because if it isn't smooth and basically perfect at the outset it will be worse after pressing.
I'd expected that the button would "iron out" many flaws, and leaving flaws behind is much more difficult than I had expected. Also, learning how much to drill undersized to allow for lapping depends totally on the quality of the first pass with the drill.
So I bought a gun drill, which I haven't yet set up, as it has to have high pressure cutting oil pumping through it to flush out swarf. I have an old hydraulic reservoir and pump that should do fine, but at every turn I'm finding that things I assumed would be straight forward and simple are difficult and complex! But that actually adds to the fun
if the path is followed to completion.
I've rifled about 6 blanks and some have turned out pretty good, certainly acceptable for a self defense handgun's functionality. Of course the goal is perfection of course.
Once I get the gun drill set up (In a commercial repair and CNC production shop, finding time is another roadblock) I hope to have answers to how exactly to process from start to finish barrels that are high quality.
I'm just a plinker and target shooter but no way near as dedicated at shooting as many guys are with callouses on the tips of their fingers from pulling the trigger and placing their trophies.
I want invaders of America, enemies from outside and within, to know there are many many of us who will take their unconstitutional assaults only so far, and that we will
always find the means to resist.