I have recently ordered a ST 15 16" M4 LE Carbine w/7"S.A.R. What I would like to know is if I will need to get a riser to ensure that my sight won't be blockd by the forward sights.

Thanks in advance.

What type of optic are you wanting to mount? Depending on the type of optic, you may want to co-witness with your front sight.

Yes, it is the Leapers UTG 3-12X44mm SWAT (http://www.opticsplanet.net/leapers-utg ... scope.html)

I want to buy a see through quick release mount, but wanted to make sure I did not need a riser first...

Thanks for any info.

Depends on the mount you get. That sight doesn't appear to include a mount, so the mount system you buy will tell you whether it is absolute co-witness (front sight is center of optic), lower 1/3 co-witness (front sight is in the bottom portion), or no co-witness (front sight is at the very bottom).

The optic you linked has a mil-dot reticle, which is tough to see a front sight post through. This means co-witnessing is somewhat pointless and you should go for lower 1/3 if you want to keep the profile of the weapon low and retain the maximum sight picture in the optic.