I am going to build up an M4gery and will likely add an ARMS SIR and eventually optics.  My question is how much interference will the standard front sight assy cause me?  Since the upper will be .22LR I won't be shooting at long distance.  
Thanks

rocketman, I asked the same question a few days ago:

[url]http://www.ar15.com/forums/topic.html?b=3&f=18&t=164621&w=myTopicPop[/url]

I went with the flip front sight from Gunsmoke:
I use a Reflex sight and don't like the front sight sticking up.  I use a few other red dot type sights and have gotten use to just looking at the red dot. That's only my opinion, some people like to CO-witness there red dot. I use them for back up only.

The flip down front sight also gives you the option to mount a low power scope low on your upper. I don't like the high rise mounts. I offend use a 4x scope when shooting out to 100 to 200 meters and like to get a good cheekwell. It offers a few more options.  

The sight is very well made and reasonably priced. It uses three set screws at the bottom to hold it in place. I recently put 200 rds nonstop and used a 120 rds drum magazine and had no problem.  By the end of the day there was well over 500 rds and no loosening. It was also 98 degrees and perfectly sunny.  I left the rifle out in the sun all day long, so hot the only thing you could touch was the vertical and pistol grip. The sight is great.   [img]http://www.gunsmokeinc.com/modules/PostKart/product_images/269.jpg[/img]