Boomerangs that reached RAAF training and frontline units were delivered under three different CAC production contract numbers: CA-12, CA-13 and CA-19, incorporating various minor improvements and modifications. A total of 250 aircraft of these marques were built: 105 CA-12s, 95 CA-13s and 49 CA-19s. The CA-13 and CA-19 are sometimes known collectively as the Boomerang Mark II. On 19 October 1942, CA-12 A46-6 (bu. no. 829) became the first Boomerang to reach a training/conversion unit, when it was transferred to No. 2 OTU, from 1 AD. No. 83 Squadron (83 Sqn) became the first fighter unit to receive Boomerangs, when several were delivered to it – replacing Airacobras – at Strathpine Airfield, in Strathpine, Queensland, on 10 April 1943. A few weeks afterward, CA-12s were also received by a frontline air defence unit, No. 84 Squadron which was stationed on Horn Island Airfield, in Torres Strait. The third Boomerang fighter unit, No. 85 Squadron – like 83 Sqn – was performing home defence duties, at RAAF Guildford (known later as Perth Airport); the Boomerangs replaced the squadron's Buffaloes.
On the evening of 20 May 1943, Flight Lieutenant Roy Goon became the first Boomerang pilot to scramble on the Australian mainland against Japanese bombers. Goon, part of an 85 Sqn detachment at RAAF Learmonth, near Exmouth, Western Australia, undertaking air defence of the Allied naval base at Exmouth Gulf (codenamed "Potshot"), took off to intercept Japanese bombers. After Goon had sighted them, the bombers dropped their payloads wide of their target and left the area. 84 Sqn had been deployed to Horn Island – a US Army Air Forces bomber base – in an attempt to address Japanese air raids and the continuing shortage of fighters in this area. The squadron was only modestly successful however. The Boomerang's low top speed and poor high altitude performance meant that No. 84 could drive off enemy attacks but rarely could get close enough to Japanese aircraft to bring their guns to bear. On the only occasion that a Boomerang did close on a Japanese aircraft, its guns jammed. There were not many air raids in this area, and after using Boomerangs for eight months No. 84 Sqn upgraded to the Kittyhawk.