Hey all, i've been wanted to do a pistol build for some time, finally settled on 10.5" for 5.56 (going to do a 7.5" 300BLK next). I saw that PSA has a deal going for their 10.5" without a handguard - $180. It's not quite what I want but it's a good price since a stripped upper and barrel alone will cost about that much. How difficult is it to take off the front sight posts and flash hider on something like this? Is the flash hider typically welded on? Also, I have another PSA upper that I like just fine, but does anyone have experience with this one?

Easy. Just clamp the barrel in a vise. Use  a piece of rubber hose and wood blocks to protect it and hold it in place if you don't have barrel vise jaws or an extension rod. A 3/4" wrench will do the trick as far as the flash hider. Remove from vise and use a 5/16 punch and/or a carpenter's nail set to remove the taper pins off the FSB. Just hit opposite of the ejection port. Do this on a hard surface like a basement floor, and on top of a block of wood to support the barrel. Have a friend hold it in place. You can then shave the FSB which is arguably the best gas block you can use.

Some cut/dremel the sight post/block without removing it from barrel.

Maybe a bit more cumbersome to do, but advantage in having it staying perfectly tightly pinned.

- OS

I wouldn't bother taking out the pins to cut down the FSB.  That's a lot of extra work with no benefit.  Just tape off the barrel, and go easy with the Dremel.  It'll be done in no time.

that's a shame you want it off.
with that PSA, I'll just add Centurion C4 9 rail, save the sweat and dollars on ammo
Like kaneljo3000 saidm best gas block.

to each his own. good luck

here's another option
Centurion Arms C4 12 FSB