You need the piercer in the centre to pierce and the correct holder to screw on the valve and hold it tight against O-ring.. I did use the 10gm bulbs, but find it more practical and much cheaper to use the larger CO2 bulbs. You need a schrader valve on your cap, this cycle inflator adapter will give total control on CO2 injected. I can get 10 x 16gm bulbs on amazon for £8.99 delivered.
pic - 12gm bulb attached and 16gm bulb.