Materials with large caloric effects offer the opportunity to replace current refrigeration technologies that require the compression of hazardous gases. Whilst magnetocaloric materials driven using magnetic fields are currently the most developed for applications, barocaloric materials driven using hydrostatic pressure are advantageous due to the relative ease and cost of creating mechanical pressure. Giant barocaloric effects have recently been observed in the material Mn3GaN, however our recent measurements on the closely related Mn3NiN reveal yet larger effects. We propose to use MERLIN to measure the inelastic neutron scattering of Mn3NiN, which has not previously been done, to better understand both (i) the specific origins of the large barocaloric effect in Mn3NiN and (ii) the underlying physics within this family of materials to aid further investigation into improved properties