Hello all,

I was wondering the other day why Colt does not make a flattop carbine utilizing
the government carbine (6520) barrel. SO, I decided to make one for myself. I notice
that the 6520 barrels don't have the F-marked front sight. I was wondering what the
implications are of putting the 6520 barrel on a Colt M4 flattop upper. I know there
are sight height differences, but will this combination work together?
Do I simply need to get a taller front sight pin? Or what?

Thanks in advance for your kind responses,

Mark Papineau
Loveland, CO

There's a difference of about 0.040" higher in the F marked front sight tower.

So, in other words, don't worry about it?

Thanks,
Mark

I bought a .040" taller front sight post from Bushmaster when I installed the ARMS 40 rear BUIS.  I found that the front sight post on my Bushmaster was out a little too far when I cowhitnessed.

I also have a Colt with the fixed front sight tower.  Like I said, there's a .040" difference.  Some people don't have a problem with adjusting their standard front post up.  I just didn't like the base of the sight post being almost passed the spring loaded pin.  Plus it wobbled a little when I touched it.

Just personal prefference.