a metering device is disclosed for use in a plastics moulding machine having a mould cavity , relatively movable platens and a feeding passage for feeding a plastics melt into the mould cavity . the metering device comprises a heated block interposed between the feeding means and the mould cavity . a cylinder with a moving piston is formed in the block . a first passage in the block connects the cylinder to the feeding means and a second passage connects the cylinder to the mould cavity . valves in the passages enable the cylinder to be filled by the feeding passage without the plastic melt entering the mould cavity and subsequently enable the desired dose of plastics melt , when ejected from the cylinder by the piston , to flow from the cylinder to the mould cavity without being returned to the feeding passage .