Warrant Officer McMahon’s instructional postings include the Parachute Training School as a static line and freefall instructor, and the Royal Military College – Duntroon, where he served as a small group instructor and drill sergeant. Warrant Officer McMahon promoted to Warrant Officer Class Two in 2015 and returned to the Parachute Training School as the Senior Instructor – Freefall, and subsequently as the Warrant Officer Development.

In 2017, Warrant Officer McMahon was posted to the 5th Battalion, The Royal Australian Regiment where he served as a Company Sergeant Major and Operations Warrant Officer. On completion of his tenure at the 5th Battalion, Warrant Officer McMahon was selected for the overseas representational posting as the Sergeant Major of the Command and Tactics Directorate at the Maneuver Center of Excellence, Fort Benning, Georgia, USA in 2020-2021.

Returning to Australia in January 2022, Warrant Officer McMahon was promoted to Warrant Officer Class One and appointed as the Regimental Sergeant Major of the 12th/40th Battalion, The Royal Tasmania Regiment. In 2023, he deployed to Egypt as the Regimental Sergeant Major of Operation MAZURKA.

On the 3rd of December 2024, Warrant Officer McMahon assumed responsibility as the Regimental Sergeant Major of the 5th/7th Battalion, The Royal Australian Regiment. Warrant Officer McMahon’s operational service includes deployments to East Timor, Afghanistan and Egypt, as well as numerous overseas training teams to the UK, US, New Caledonia and Indonesia. In 2017 Warrant Officer McMahon was selected to attend the Apollo Future War Analysis course at CDSS. He has completed a Masters of War Studies (UNSW) and a Masters of Strategy and Security (UNSW).

Warrant Officer McMahon is married to Tammy and together they are blessed with two teenage daughters, Grace and Peyton. In his spare time, Warrant Officer McMahon enjoys cycling, working on his excessively high golfing handicap, supporting the ACT Brumbies, and travelling with his family.