I have a Bushmaster style disapator, the 16" bbl, full length front sight radius, with the carbine length gas system, with a Hogue monogrip fore end.

It's a nice set up, but I'd like a full length top rail for my 552, Mag, BUIS, an Pez dispensor.

What replacement options do I have?

When buying a replacement fore end, which lenght do I need, the 12"?

Any problems you see fitting the new forend over the shaved sight post that's in the middle of the fore end?

And what one piece, free float, quad rail fore end would you recommend?

Thanks,

I built a dissy style carbine a while back, I used a Denny's Operator midlength, midweight barrel and a DD Lite 12" rail.  I cut down the original FSB for use as a low profile gas block, it required a lot of grinder work to fit under the rail.  I bored new holes for the pins to accomodate the FSB in it's new position.  I am very pleased with this build, and would do it again the same way.  My two favorite rails are the LaRue and the DD Lite, both are solid, well made and are easy to install with rudimentary skills and equipment.