Newbie AR FSB Questions

[Fish609]

OK. I have built my lower and would like to finish this upper before summer is over. I am starting to get serious but I have quite a few questions about how to build this thing. I guess I will just ask and please reference the question number if you have any advice. As always THANK YOU SO MUCH in advance for all your help!!!

Here is my planned upper:
Std Flat Top Upper
16" Barrel
Phantom Hider
Std gas tube
Flip up front site or standard F marked (not sure)
MI Car Length FF hand guard

1. Flip up front sites, such as YHM or MI brands -> Do I need to cut holes in my barrel for these? Do they pin on like a standard FSB? If I get a barrel with a standard FSB and switch it out later for the aforementioned ones am I going to have a ton of holes in the barrel?

2. BUIS -> Do these specifically relate to the front site? Am I going to have to get a matching set depending on what flip up front site I get?

3. Standard sights + Optics -> Will the standard F marked FSB get in the way of a scope, aimpoint, or ACOG style optic? Are you pretty much forced into getting a flip up front if I go with one of these options?

Well I guess all my questions relate to the FSB. Confusing little buggers. Any help will be appreciated!

[SandmanKC]

1. If you get the style that replace the FSB, you should not need any other holes. They'll mount right were the FSB is (just make sure it's for your diamete barrel). A lot of flip up sights mount on rails, so you may just have to get a new gas block with a rail on top to mount the sight.

2. As far as I know, you should be able to "mix and match" most any front sight with a rear sight. The ones made for ARs should all mount at the same height.

3. The standard front sight should not get in the way depending on what mount you use. EOTechs will co witness perfectly with stock front sights. Aimpoints (depending on mount) usually have the stock sight in the lower 1/3 of the optic. I'm personally not sure of the ACOGs, but would imagine they'll at least mount as high as stock sights (if not higher). Don't worry about scopes either. With the zoom of a scope, the front sight should be blurred out, and a non-issue.

[Fish609]

I'd like an ACOG but boy are those expensive lol.

Can you replace the tritium when it burns out?

[mvician]

Originally Posted by Fish609

I'd like an ACOG but boy are those expensive lol.

Can you replace the tritium when it burns out?

$650 is the most I've paid for a "like new" TA31A
and yes the tritium can be replaced

3. The standard FSB is not in the way with an optic, with a red dot the dot will be
above the front sight post, and under magnification will blur out.

2. you can match brands or go different front and back.

1. The flip ups FSB usually "clamp" or hold with setscrews
if you start with a standard FSB and switch to say the YHM, yes there will be 2 pin holes
under the barrel that will be covered.

[Fish609]

Great information. Any other suggestions?