A.R.M.S. #50SC Bi-Level S.I.R. System - Plastic?

AR/M4 AR Technical Discussion
1

Hello Everyone -

I ran across a statement in an old post from 2009 dealing with the A.R.M.S. #50SC Bi-Level S.I.R. System. I know some don’t like old threads coming back to life so here’s a new one.

The statement in the old thread is:

“Non-Technical response: It’s a piece of shit. The bottom 1/2 is plastic and too many screws come loose.”

Are the bottoms really made out of plastic?

Thanks,
Larry

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yes…some type of polymer

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My dept issued swat rifle has the military version of the rail you are asking about. It is very heavy and yes the bottom rail is plastic. I will say that it has proven to be durable though. We have the rails on sim uppers and our regular uppers. They get beat up pretty good in training and to knowledge they have never failed.

Don’t get me wrong I would not choose this rail for any of my own rifles and I am in the process of having the arms rails replaced.

Matt

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Thanks for the responses!

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Forgot to ask - what would you recommend other than the ARMS rail?

To be honest, I like the way it looks but most of all I like how the BUIS is streamlined when folded down.

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I have one on my personal gun. So far, I like it but I have not been able to really put it though it’s paces like a military gun.

The bottom is some sort of plastic - sort of reminds me of what a Pelican case is made of. Swann does ship it out with red loc-tite for the mounting screws. I would call that a clue - use the loc-tite. The plastic piece is held on by Dzus type fasteners. They come off easily for cleaning but do not require loc-tite.

The two feature I do like about this system is it gives you a riser mount for an EOTech and it lowers a PEQ-2 below your FOV. In fact, it is the lowest PEQ mounting I have found. However, I don’t think most folks have this requirement.