I will be purchasing a rear sight for my flattop upper by the end of this weekend and I was going to get the ARMS #40 for my BUIS but then I started to think about a fixed rear sight like the LMT.  If it matters, I'll be putting an Aimpoint ML2 on for my optic setup.  This is my first experience with BUIS so I need the experts to weigh in on which is better, or maybe better put, the pros vs cons of each.  Thanks for the help!

LMT will be more durable, but heavier and it will be in your line of sight through your optics. Its also more adjustable. ARMS is out of the way, and light.

I am no expert.... but I like flip ups... my shooting is recreational... I am not going to the sandbox anytime soon... so I like the unrestricted view of a flip-up...

And thus far, from all the choices I have seen, I like the ARMS#40L the best.

This is an ARMS#40 (non L) with the ML2, like you are thinking:

I like my ARMS #40. I don't really understand this fixation on speed of deployment some people have, thus ruling out using one on their rifle. It's their choice, and I will admit that an LMT sight is more durable by design, but I wouldn't get one because it's "faster" to use. It takes all of half a second to pull the retaining lever on an ARMS #40 sight. Most people primarily use a red dot or some other optic anyway when they're using a BUIS on their rifle.

You need a folder to fit under scopes:


For non-magnified optics like this ML2, I use a fixed LMT buis.   It doesn't really restrict my view, since non-magnified optics like the Aimpoint are meant to be used with both eyes open.



My LMT buis is for sale for $90 on the Equipment Exchange .