I'm thinking of purchasing a Ultra Shot Pro Spec NV QD made by Sightmark.  It looks a little bit like an Eotech, but with a lower price tag to fit my budget.  My question is whether or not it will work with my AR15 with the fixed front sight post.  Its seems that the front sight would be in the way.  Does anyone know if I should get an additional rail for my flat top reciever to get the reticle up over the front sight post?  Or should it be okay?  Any advice would be appreciated.

The front sight post will be in view, same as an Eotech, Aimpoint or any other non-magnified optic. People just learn to live with it. Google some pics of Eotech or Aimpoint and you'll likely find that most ARs (and military & law enforcement) have fixed front sights.

If it bothers you that much you could replace the front sight with a folding front sight. If you have a quad rail hand guard then you could replace the front sight with a gas block and install a front flip sight on the rail. Some use a railed gas block and install a front flip sight onto the railed gas block.

FWIW I have the non NV ultra shot, but I think they are basically the same other than that.  I have a fixed front sight post and have the sightmark mounted directly to my flattop, no riser. I use the circle w/ dot reticle and the dot sits on the tip of my front sight post. If I flip up my rear sight, the reticle is pretty much centered in the sight picture.

I think this is what's called absolute co-witness. The front sight is always there in the sight picture, but you really don't notice it like you think you would.

I have the SM14000 QD sight and just took it back to the dealer today. I wanted a Eotech'ish sight as I run Eotechs on my rigs and this one was just for a suppressed 22 AR SBR that I will be plinking with at the range. (not finished building it yet)

So, I tested the sight out on my M&P15 shooting .223 Fed bulk ammo. Well, it worked well for about 6 shots and then it would turn off. It would turn on when I pushed the switch but after 2 to 3 shots it would do it all over and this went on for 2 mags. I checked the batterys and the spring pressure was good and every thing was tight. I am guessing it is/was in the electronics.

I called my dealer and he said he would trade it out for another one. I will be testing the new one out tomorrow to see if this one works. If not, it will be going back, and my dealer said that he will stop selling Sightmark sights depending on my results.

I will post tomorrow night after testing.

Side note: I did notice shooting at 200 yds yesterday with the sightmark it was tough to see the swingers (unlike the Eotech). It is due to the blue tinted glass in the hub. I took the sight off and was ringing them with my irons with no problems. This sight may be ok for any shooing at 100 or less yards and this is why it is going on a .22 and nothing for serious use.

Thanks for the advice.  Mine should be here in a few days.  We'll see how it does.

Ok, Got back from the range.

I am glad to say that the replacement sight did in deed work and worked well.

I sighted it in with the single dot floating right above the sight post and it was dead on with the first shot and held zero with repeated take off and back on.

The sight never lost function with 210 rounds of .223 Fed bulk ammo.

I can now trust it to run well on my 22LR upper later on.

I called my gun dealer and told him the good news and he was happy to hear of my findings. He will keep in touch with me to see if any other or same problems arise later. He will keep stocking the SightMarks as of now.

I still didn't like the blue tint keeping me from getting good hits out to 200yrds. It's like shooting with real dark sunglasses on. The dot is nice and bright but the tint on the hub is just too dark for a good sight picture out past 100 or so yards.

I will update if I run into some other problems down the road.

Thanks for the update.  Good luck.

I got mine in yesterday.  I slapped it on my upper and it lined up perfectly with the front sight post right out of the box.  The front sight is not a distraction at all.   Seems to be a good item.  Thanks for the comments.

Glad it's working for you so far. Just don't use this sight as a "go-to gun sight", It's fine for just playful range fun.

Actually I would prefer the 1/3 cowitness myself. I may get a cheap riser later for mine.