Perhaps, at a stretch, his admitted behaviour was/is normal for the Army.
Things have obviously changed, when I was in the mob, (pre IRA activites 1969), as a member of the regimental shooting team I kept my weapon with me in barracks or at home in a WD Hiring. We didn't put them in the armoury as they had all been zeroed to ourselves and we didn't want them mixed up with others.
Also, in those days, being a member of HM military was considered as a licence to sensibly and safely carry and possess firearms, no police licence needed.