Guy's,

  I've got a bushmaster target model with a 20" barrel.

It's a A2, and I want to make it a flat top, so what I'm wondering is what's the best type of free float tube to put on it, and since it will be a flat top, where can I get a FSB that is cut down.

Of course I could go buy a new upper and put this one aside, but I think it would be cheaper to change out the upper reciever, and forearm.

   I'm just a bit concerned about head space but since the bolt /barrel will be the same I don't think it's an issue.

Any tips.. and what's the best type of tube & where can I get the cut down FSB.

Thanks,
Spot

the FSB that is on your barrel is now part of an assembly

When it was assembled, holes were drilled thought the FSB and thru the edge of the barrel

getting a new FSB to use the existing tapered holes in the barrel
requires Jedi magic

one option would be to grind the existing base down

Doc,

  That explains alot!  Cool..

 Hmm.. now it's either get a new barrel also OR just buy the new upper.

I'm thinking a second upper is the way to go, and if I really don't want the old A2 upper I could always sell it.

I don't think I could use a bolt on fold down front sight if I cut it down so if I want flexibility I really need to get a new barrel with that type of modular front Sight Base.

Thanks!  that's exactly what i needed to know.

Spot

there are also FSBs that are held on with set screws

they are not bayonet charge proof
but they do work well

for a FF tube i like the PRI model
www.adcofirearms.com/sprbuild.cfm?page=build