"straggler" is probably an american term since onoda's autobiographical novel didn't use the term. but the american-authored book "the stragglers" did.

most stragglers knew the war was over and they decided to either stay in hiding or go native (for some reason or another.) some even resorted to canibalism. the most bizarre was the case in anatahan, involving a group that included one japanese woman.

what set onoda apart (aside from being a commissioned officer,) was that he believed the war was still on, and that he waged a guerilla war continuosly until his surrender in 1974. he was fighting (and killing) the preceived enemy up to the 70s.

'high-powered' is admittedly a journalist's term but someone familiar with firearms could easily understand the meaning to probably include any rifle cartridge capable of velocities well past 2,000 fps, or has a lethal range past 200 meters. that's my own convenient definition so it classifies the m-1 carbine round as a medium- to low power .30 cal.

30-'06, .303LE, 7.9mm mauser, your pick.