Hi everyone,
I am contemplating getting a set of 9.0 Larue rails. I have a carbine length gas system with a standard front sight base.
The upper is a factory LMT upper. If I were to cut the Front Sight base down, would it be possible to buy a new front sight base later on if I wanted to go back to the carbine length handguard setup? Or is each front sight base cut specifically to its corresponding barrel?
Thanks for any help you can offer.
-B:D
The answer to your question is yes, but… 
If your front sight base is attached with taper pins, then you will have problems. The base is installed, and then the tapered holes are drilled and reamed through the base and the barrel. If you want to revert to a standard FSB, the best solution would be to drill and tap the new sight base for four setscrews, and mill corresponding flat spots on the barrel for them to bear against. This is how most ‘match’ FSBs are installed, to allow for windage compensation.
As you’re probably beginning to realize by now, you’d be time and money ahead to simply remove your existing FSB and install a gas block. That way if you ever decide to revert to the original FSB, it’s simple to reinstall it.
+1… sound post.
get a low-pro and save the FSB… it’s the only one on earth that fits.
Thanks guys. Low Pro gas block is the way I’m gonna go. That way if I want, or if I have to, then I will be able to put on the old FSB.
Thanks!
-B:D