A Practical Examination of eBay Rifling Buttons
Contributed by: PRKR
I’ve been on a personal quest to make rifled barrels from scratch for several years now. Starting with a drill press, I’d eventually buy a lathe with barrel-making as the primary reason to justify that purchase. While I overcame many challenges that come with hobby barrel production, the one thing that has continued to haunt me for years is producing the rifling.
Rifling is the helical grooves on the inside of a barrel. They are what imparts spin on the bullet to give it stability in flight. Everything about making a barrel is simple and pretty much boils down to making a hole. That is, until you get to the rifling. Rifling involves making multiple grooves of a uniform depth, width, and twist, down the entire length of the bore. This is not something that’s easy to accomplish with standard shop tools or by hand.
I’ve personally tried broach cutting each individual groove with a custom mandrel using a rifling attachment designed for my lathe, and I’ve tried electrochemical machining (which is using an electrode that has a negative of the rifling to create grooves in a barrel with electricity and chemical reactions). These methods were not satisfactory, and I looked towards alternatives.
Button rifling is a forming process in which a hard piece of metal with rifling grooves is pushed through a bore, causing the metal in the barrel to flow into the empty spaces in the button and move away from the raised portions of the button. As the button moves down the barrel it turns on its own, creating helical ridges known as rifling. For the same reasons it’s hard to make helical grooves inside a bore, it is also difficult to make them on the outside of a cylinder. This, coupled with the difficulty of machining the incredibly hard material that buttons need to be made out of, made it impossible for me to simply make my own button.
However, cheap foreign rifling buttons have recently appeared on eBay. Since I was rapidly running out of alternatives, I decided to pick one up and give it a try, and in the process talk a little about them. If you’re considering purchasing one read through the whole article because there are some pretty important details you should be aware of.
NOTE: I purchased this button with my own money and am in no way being influenced by any eBay seller.
What’s Out There
There are two main types of buttons you can get from eBay: Ukrainian and Chinese (Hong Kong). The Ukrainian buttons are made out of tool steel and have a “nano coating”. The Chinese buttons are made out of carbide and have a titanium nitride coating. As carbide is very hard, and therefore brittle, it does not work well with shock. You cannot hammer a carbide button through a barrel without risk of shattering it. You need to use a hydraulic press or some other method that does not shock the button. Since I already had a hydraulic press, I decided to go with the carbide.
I ordered from the seller ‘topestore48‘. They had 7 different calibers to choose from; 5.5, 5.56, 5.6, 6.35, 7.62, 9.0, and 11.43 and four different styles of buttons in those calibers. Style one and two were 6 groove buttons, one had a boss above the rifling itself and two did not. Three and four were 12 groove buttons, and like the 6 groove options, three had the boss and four did not.
I ordered option one, a six groove 9mm button with a boss. 16 days later the button arrived in the mail.
Since there were no advertised dimensions other than “9.0mm” I took some measurements when it arrived. I wanted to see what the rifling was checking at. The pilot diameter was .350 and the rifling diameter was .368. This was strange to me as I already knew that the SAAMI spec for 9mm was a .346 land and .355 grooves. I took a moment to consider this, recalled that China is a combloc country, and came to the realization that I had a button designed to rifle a 9mm Makarov barrel.
Rifling the Barrel
Despite the size snafu I pressed on and worked within the new parameters. Instead of reaming to the SAAMI spec of .346 for 9mm Parabellum, I reamed to .351. Just large enough for the pilot to fit in the bore. (Do not try to press a button through a hole if the pilot won’t fit)
With reaming completed we can press the button through the barrel. This is a pretty simple operation so I won’t go into too much detail. Make sure you put the pilot in barrel so the rifling and boss remains on top. Make sure to lubricate the button! I just used some cheap Walmart brand multi purpose grease.
After you press the button in to the point where the boss is flush, use a small disc to press it below flush.
Once the small disc has been removed switch to a longer pin.
Now simply push the button through.
The rifling produced.
There was only about .002 of engagement with the rifling. I decided to push a pulled .380 projectile through to check the engagement.
The projectile would not fall through the barrel, which is a good sign. However, I only had to use light taps with a ramrod to get it to pass all the way through the barrel. The projectile should resist more than just light taps as it’s supposed to be digging into the rifling. It appears that the rifling was deep enough to only significantly engage one side. This is not optimal but it’s serviceable enough. Additionally, when a round is actually fired the projectile may expand a little due to the pressure. This should help it engage the rifling a little more.
Coming into this I didn’t have very high expectations, and right off the bat the eBay seller did not inspire much confidence. The lack of technical details didn’t help either, but I bought it understanding that there was a high chance it wouldn’t work at all. As it turned out it actually does work… for 9mm Makarov barrels.
As far as 9mm parabellum barrels go, it may work if you use a .3501 diameter reamer and if the projectile expands when fired. At the very least it will fill the requirements that need to be met for non NFA builds.
All in all this venture was technically successful, but not something I would say I’m satisfied with. Keep an eye out for more gunsmithing articles, as I will be trying out further buttons and methods!