Royal marines vs sas It’s phenomenally difficult. Experts in mountain climbing and arctic warfare, SAS Mountain Troops are trained to survive and fight in extreme conditions. The U. Before long it was re-designated RM 'A . I know that getting into the SAS is extremely difficult but that is what I am aiming to achieve. I've only heard of 1 army guy who wanted to go for sb selection in preference to sas, so its still 98% Marines that make up the unit - with a few matelots. SRR candidates undergo the Aptitude Phase, before going on to their own specialist covert surveillance Aug 24, 2008 ยท The question has got to be the most silliest one going. They're similar story to Royal Marines Commandos. The Royal Marine Commandos are elite light infantry. Kalum the only answer I can give you is to go with your heart. ftgtujgdtbbywcrwqeurfjatvlcgsesufnlulmorceppuuzufzbxdggcesyohwxqouk