How BBs are made
by B.B. Pelletier
This report was requested by blog reader Wulfraed in one of his comments.
For the benefit of those who shoot airsoft guns, the BB I am addressing today is the steel BB that historical BB guns shoot — not the 6mm plastic ball that Asian-made airsoft guns started using in the 1970s.
The first BB used in an air rifle was BB-sized lead shot used by shotgunners. In the day when it was popular (the 1880s), shot was sold in bags in hardware stores and came in various numerical and letter sizes, including sizes B, BB and BBB. BB shot was supposed to be 0.180 inches in diameter and weigh more than nine grains.
At the turn of the 20th century, Daisy reduced the size of what they always called air rifle shot to a lead ball 0.175 inches in diameter. That saved them lead and also went faster because it was a lighter ball.
In the 1920s Daisy discovered that some boys in Minneapolis were using steel ball bearings that they were salvaging from a reject pile behind the American Ball Company. They checked the sizes of the balls they wanted to shoot by dropping them through the bores of their shot tubes. If they passed through, they were fired. If they stuck, well, a huge influx of stuck steel balls in shots tubes was what got Daisy’s attention in the first place.
Long story short, Daisy bought American Ball and started making their own steel air rifle shot. It was sized 0.171-0.173 inches, nominally. They had to change the size and design of their shot tubes to accommodate the new shot, and some time late in the 1920s BB began rebounding from hard targets with great force — something the soft lead balls had not done. This started the mothers of American warning against shooting your eye out.
So, how do they make a perfectly round sphere of steel? You can’t afford to cast steel into balls, nor can you afford to forge or swage the balls — again, because of economy.
So, how is it done? Pretty simply when you understand how it works.
Ever roll a piece of clay into a ball? You hold it between your palms and rotate each hand in the opposite direction. Has anyone not done this as a child?
So, short of being Superman, how do you roll a piece of steel into a ball? Well, it helps to have hands of steel, and that’s exactly how they do it.
The first step is to get a piece of steel that’s close to the right size, which means the same mass as the ball (BB) you wish to make. An easy way to do this is to take a spool of steel wire and cut it into precise chunks, then feed them between two hardened steel plates that have spiral grooves cut in their mating faces. Each plate is several feel across.
Each large spool of steel wire weighs about a ton (2,000 lbs.). These are fed into a precision wire cutter that slices off exact chunks the right size to make one steel BB. You can see by the amount of wire on hand that they intend making millions!
This wire-slicing process is called heading; and if it isn’t done precisely, the finished BB may be spherical, but have one or more small flat spots in its surface. This defect comes from improper heading and is very difficult to sort out during the manufacturing process.
The plates are smooth on their surfaces, except for the spiral grooves. The chunks fall into the grooves as the two plates rotate in opposite directions — like your hands rolling a piece of clay into a ball. The spiral grooves catch the sharp edges of the cut steel pieces and roll them around as the plates turn. Once the pieces fall into a spiral, they cannot get back out, so they remain in the groove, tumbling and rolling around.
The spirals also become more shallow as they spiral in the plates, so the balls can’t stop tumbling and rolling, and they cannot back out. As the steel plates turn, the balls are forced in the same direction, which makes them smaller and rounder as they go. In the end, most of them roll into near-perfect spheres — just like the clay balls you rolled in your hands.
I would like to show you these steel plates; but this part of the BB-making process is considered proprietary, and I was not allowed to photograph it.
These balls are not yet BBs. But back to this rolling process a minute. The manufacturer feeds thousands of chunks of steel each hour into each set of plates they have working, and when the chunks are rolled into near-perfect balls, they then drop out of the plates. Some kinds of imperfect balls will also drop out, but they’ll be caught later on.
So, thousands of round balls per hour come from each set of rotating steel plates. The balls that exit each set of plates are carried by conveyor to a metal-plating machine where they receive a very thin coating of rust-inhibiting metal. As raw steel balls, they would start to rust almost immediately; but when uniformly plated with copper or zinc, the steel is sealed from the air and the BBs can last for years without oxidizing.
Once they’re plated, they’re sorted by several processes. One process rolls them down a spiral channel where the smooth BBs pick up speed and roll up on the sides of the channel from centrifugal force — much like a bobsled going downhill, while those that have some rough spots roll slower and more bumpily, staying in the center of the slide where they eventually drop through holes and are eliminated. What passes this test are finished BBs.
They may be graded by size at this point, by passing over holes of different sizes and then being sent to different places for packaging into different products. If any are too small or too large, or if they have any flashing or other imperfections, they’ll usually be caught in this last test.
Start to finish, the process takes some time, measured in hours because of queing and transit time. The actual manufacturing time is much less. Crosman runs three shifts a day and cranks out 4 million finished BBs every 24 hours.
Daisy used to make its BBs this way, or by a process that was very similar, but they have now moved the manufacture of their BBs offshore. They receive 55-gallon drums of finished BBs from their foreign manufacturer, which they then sort before packaging. Their BBs are extremely uniform, so the process works regardless of where the BBs are made.