Can a scope go on any upper without a handle?

TH3180 · 04-05-2011, 21:20

I got the bug I want an AR-15. I have been researching for the last couple weeks. I still haven’t decided what I am going to get. I am confused about something and I am hoping you guys can help me out. I have a picture here that I circled the part in question. If I bought this upper or any other that looked like it wouldn’t the circled part get in the way of a red dot or scope? From everything I can find, part of the gas system runs through that so I assume I can’t remove it. I’m sure I will have many more questions but this is the only one for now.
Any good advice you can add please do so. There is so much info out there it is hard to even know where to start.
Here is the picture.

trlcavscout · 04-05-2011, 21:29

I prefer a front site like the one pictured when useing red dot's for a co-witness. But you can have the top chopped off of your existing front site or go with a low profile gas block if you are going to run a scope.

Eurodriver · 04-05-2011, 21:36

That part is called the front sight base, the bottom part (what you refer to as "the gas running through it so it is necessary") is called the gas block.

If you are using a magnified scope of at least 4x you won't even see it.

My suggestion is to spend alot of time reading the stickies at www.m4carbine.net in the AR General Forum before making a purchase.

bel970 · 04-05-2011, 21:38

it's removable, some are easier than others. and you barely see the front sight in the scope anyway but if that is your plan get a upper that has a flip up, railed or low profile gas block.

***JimBianchi*** · 04-05-2011, 21:45

I added a small riser to my upper.

Gives me a better sight picture and gets the scope above the post.

Riser came from Sportsman Guide for $8.

It's been on for about a 1k rounds, works great.

mixflip · 04-05-2011, 22:27

That part is the FSB = front sight block.

Option #1 leave it. Mount your red dot and a BUIS so you can transition to irons if/when your battery powered optic fails. The in-line design of the Ar15 kinda demands a raised sight picture so the A-frame FSB is actually a good thing. Plus its rock soild and battle tested.

Option #2 take it off. (it can be done) Replace it with a low profile FSB and run BUIS (back up iron sights aka flip up sights) front and back on a mid-length handguard for a nice long sight radius.

Or mount a FSB with picatinny rails if you want to keep the stock handguards but still want BUIS front and back?

Or mount a FSB with a built in flip up sight?

ColdBlooded · 04-05-2011, 23:55

The higher the magnification the less apparent the fsb will be, especially if you use a Burris PEPR, Larue SPR mount, or one of the other high profile mounts.

jedi573 · 04-06-2011, 07:22

I have a 0x (no magnification) Aimpoint on my gun, and a conventional front sight like the one pictured. I can see the front sight when I'm shooting, but as my interest is on the red dot, and my focus is on the target, I don't even notice the front sight.

Not too much of an issue, for my setup, anyway.

Andy

TH3180 · 04-06-2011, 15:04

If that gas block was in the way of my Red Dot I could replace it with something like this right?
http://www.midwayusa.com/browse/Brow...807***11619***

Yankee Hill Machine Gas Block Low Profile Clamp-On AR-15 Standard Barrel 0.750" Inside Diameter Steel Matte

CAcop · 04-06-2011, 15:19

That is more meant for under the handguards.

Basically people will remove the FSB and then run free float handguards over it. Then they can add front and rear flip up iron sights if they want to not have iron sights in the way.

Like mixflip said some people like running iron sights in the way in case the optic goes down.

Jack Black · 04-06-2011, 15:30

If you're using a non-magnified sight, like a red dot, you have a choice of how high you want to mount it. I had mine mounted at what's called a 1/3 cowitness. What that means is that you can use the iron sights looking through the red dot, but the iron sights will be level to the bottom third of the red dot. In this case the front sight base is visible when I look through the red dot, but since my focus is on the target it doesn't bother me at all. It's up to the individual whether the front sight base bothers them or not. There's also absolute cowitness where the red dot sight sits lower.

I also have a 1-4x sight. When the magnification gets to about 2.5x, the FSB completely disappears from view.

Here's a pic of what cowitness looks like.

Flashbang1063 · 04-06-2011, 15:36

It's not an issue. With an Aimpoint, Eotech or other RDS you mount it to have either an absolute or lower 1/3 co-witness with your front sight.

Absolute: red dot sits at the top of your front sight post
Lower 1/3: front sight post sits at the lower 1/3 (below) of your red dot

As far as magnified optics...with my scope at 1x the front sight post is visible, but blurry...it is not distracting at all. At 4x it blurs to the point of almost disappearing.

Trijicon at 4x magnification:

It is fine to keep the front sight and run optics...it's the rear sight that you want out of the way.