I have a Colt rifle with the Surefire M500 full forend light.  What I want to know is if a 0.5 inch riser would place the Eotech 552 too high for the fixed A2 front sight.

What I'm ultimately trying to do is push the eotech forward enough to fit the Larue magnifier flip mount behind it.  As it stands currently, the handguard is slightly above the flat top rail limiting real estate on receiver top.  

Any suggestions would be appreciated.  I don't want to have to buy a railed forend and new light.

The standard height of the iron sights is 1.4" above the rail.  With an absolute co-wittness, the EoTech reticle and the iron sight line-of-sight are in the center of the EoTech glass screen, or 1.4" above the rail. The "screen" on my 552 is approximately 1" high.  If you elevated the EoTech 1/2", the iron sights would be at the very bottom or even below the field of view of the EoTech, and if my arithmetic is corrrect that would make the iron sights unusable. It's late and I could be FOS, but that's how I would call it.

Added:  Take a look at GG&G's website. GG&G It states that a half inch riser prevents co-wittnessing of an EoTech.  They're trying to sell their Accucam, with the selling point being that it doesn't raise the EoTech, whereas other alternatives raise the EoTech 1/2 inch or more which prevent co-wittness.

It that is the case, what are my options to mounting an eotech and a magnifier while retaining the standard handguard?

If your objective is to mount an EoTech 552 and an optic multiplier, and a fold-down BUIS within the confines of just the receiver rail, I'm nowhere near smart enough to know how to do that.  I had to mount forward railed grips so that I could push the 552 forward enough to get good access to the EoTech buttons with a BUIS installed behind it.  I believe that I could install an optic multplier behind the EoTech, but there wouldn't be any room for any kind of rear sight that I'm aware of. Currently, my 552 extends approximately 2" beyond the fwd edge of the receiver rail, and there's also about 2" between the EoTech and the ARMS40L mounted behind it.

There's plenty of folks who post here that know all the options so until one of those guys checks in with some suggestions that's all I can do .  Good luck.