so many AR acronyms to get used too.. google answers a lot of them.. but MBUS stands for Magpul back up sight.. Back up for what?!?

 

like backup meaning "in the case that something fails"? Like send backup! or backup because it flips up? and when i see pictures of the front sight up, and an optic on the rail.. do you guys look through the optic and the front sight at the same time?

Back up sights are usually fold down and snap up into place should your red dot or other optic break. I fold down the BUS when using the red dot.

ahhhh..

 

thank you.

They are called backup sights because it is assumed you have some kind of optics (red dot, reflex, glass) as your primary sighting device.

Magpul had to come-up with their own acronym (MBUS), since their sights are polymer. The standard is BUIS - which, of course, is "Back-up Iron Sights"