Hello all -

I have a question regarding MagPul BUIS front sights.  The sights that I have seem to be missing a part, a detent to keep the post from moving (a guess).  Please see the attached pictures, notice in yellow.  I think it is missing a detent for the post so it does not move when zeroed.  Am I missing a detent or is that how these sights come?  Any advice on what exactly I need to fix these sights?  It seems that when I fire the zero is lost since the post is moving freely.  See pics.







I did a search and did not find an answer on this question, my apologies if this is re-post.

If you bought the sight new it should have came with roll pins you can put in that hole to lock the sight.

Negative. Do you have any suggestion on where to get them?

According to the instructions that came with mine, the sizes are 3/32x3/8 and 3/32x1/2.  You use the longer one if your sight is cranked way out.  I bet if you contacted Magpul they'd stick some in an envelope for you, or you could look at a hardware store.

They come in a small baggie along with the sights. Try Magpul to get replacements.

If Magpul won't send you one for free PM me your address and I'll send you one.

Is there anyway you can scan those instructions to me?  I contacted MagPul and got this response.  

Thank you for your inquiry.  The MBUS instructions can be found on our website here:

http://store.magpul.com/downloads/MBUS%205x7_090514_Update.pdf

The Front MBUS does not utilize a detent for the post since simple friction will keep it from rotating on its own.

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Is there two generations of these BUISs?  My sight does not stay in with friction.  It will rotate on a single fire.  I am going to have to stop by the hardware store.  

I got a 3/32 x 1/2 tension pin at Home Depot and it is secure now.  Thanks for the advice all.