Sure fits. Thanks to some quick work by reader RM, check out this Bebo page on a certain Michael Dwyer.
Let's check the points in common
1) Is Irish
2) Loves guns and fancies himself as a sniper
3) Is definitely in South America and according to messages left by friends is in Bolivia
4) Has Bruce Willis's "The Jackal" as the answer to his "What kind of Assassin are You?" profile box
5) Thinks he's hard
6) Member of an Irish battlefield simulation club
UPDATE: I've been told that Bebo has now pulled his page, but I took a swipe of it yesterday and saved it on my PC. Here's a link to the PDF copy. I've removed the comments from friends out of respect for third parties but the rest is how it was. For your information, several newspaper journalists have been mailing and asking questions on this story, including Irish, US and world media. I haven't told them a thing of use and they get the same treatment as the people that really matter, i.e. the grassroots readers.
UPDATE: Yep, it was him alright.