The Orlando nightclub shootings that left 49 people dead confirm terrorists’ increasing preference for guns over bombs, according to catastrophe modeller RMS.

Off-the-shelf military weapons are “inherently more reliable” than improvised explosive devices, it says.

“For example, a vehicle bomb… against the Tiger Tiger nightclub in London in 2007 failed to detonate for technical reasons,” RMS Catastrophe Risk Expert Gordon Woo said.

“In addition, ‘lone-wolf’ attacks, as appears to have been the case with Omar Mateen in Orlando, have a comparatively small chance of being detected and stopped by counter-terrorist agencies monitoring communications.”

Dr Woo says while terrorist attacks seem random, there are patterns that mean the risk can be modelled.

As previously reported by insuranceNEWS.com.au, Aon’s latest Terrorism and Political Violence Risk Map shows that since the start of last year, 52% of terrorist assaults in Western countries have been “armed attacks”, compared with 34% bombings.