I know it's been asked before but I want to know how durable the M900a's are.  

Is it able to handle muzzle strikes and still function?

How about a hard shot on the vertical grip base if it hits the ground when quickly going prone?

If I go with the M900a it will be mounted on my SIR 50.  When on the SIR I noticed that the vertical grip seems to hang about as low as the magazine.  Has the M900a's low vertical grip got in the way of things or make gun handling awkward?  I like using vetical grip but I was concerned that the length and bulk of the M900a would be a hinderance compared to the standard KAC vertical grip.

Thanks!

thats why I went with the dieter grip and the 962 light, the 900 was making it difficult to shoot barricades and some prone and I can take the grip off and leave the light or vice versa, it gave me more options to keep them seperate.  Its a fine product it just didnt suit my needs.

After thousands of rounds on a 900 equipped M4 I've had only one problem. What occured was I was using the optional turbo head at the time. I had equipped it with the IR filter tip off and when I did so the top of the IR cover was toucing the bayonet lug. Under fire the recoil or barrel vibrations transmitted to the cover and caused the bulb to disintegrate. But that was kind of a fluke example perhaps. I've since switched to a different RAS system than the normal one and it avoids contact at all with the turbo IR setup. But I've recently been running the 1.6" bezel anyway.

Other than that, no problems.

Have you done any muzzle strikes with it yet?

Nope. But I did mean to add that when using a 30 round magazine the light has never hit the ground due to length. But I'm using the RAS instead of the SIR.

Wes:

A bayonet would block the light on my M900.  Just use the Vortex flass hider.

S/F

Sub