I have an Optics ready S&W AR15 that I would like to mount a green laser that I have on my 15-22. Nor lower or side rails present so I cant use current mounting system. Top mount would interfere with the optics. Any ideas on bottom mount would be appreciated. I know there is a hole for a front sling mount and wondered how this can be used.

Well, that hole in the gas block is for a QD (quick detach) sling swivel. And while you can find qd rail mounts to attach a sling swivel to a rail, I haven't seen any rails with a qd used for attachment.

Second, you might be interested in a GG&G UFIR (under forearm integrated rail) - see Under Foregrip Picatinny 1913 Rail - Mil-STD Forearm Rail Mount System

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S&W M&P-15 OR

Used the second option with great results. Now have my Lasar and light mounted on bottom.

Since the factory hand guard is quite tapered, how did it go with sighting in the laser? What distance did you sight it for and how much does your point of impact change when changing distance to target?

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Stu

I used a .223 laser boresight cartrige and matched up the external laser and red dot reflex sight at aprox. 30 yards (did this indoors at my Martial Arts school). The lasar has windage and elevation adjustments so the tapered hand guard was not an issue. I will be taking the gun to the range on sunday. Usually sighting in at about 25-30 yards tends to do fairly well for shots out to about 100 yards. Will test this on Sunday with this rifle to see how accurate it is and post results.
BTW changed my mind about the green laser and left it on my 15-22 and purchased a strong 635 red laser (good day visibility but not as good as green) and 150 lumen light compact combo that fits great on the rifle.