Removable or flip up sights. Questions.

[Aka Zero]

I am planning on building an ar soon. Want to shoot iron sights at first. And switch to a scope later.

Problem is, I noticed that most gas block rails are slightly lower that a standard flat-top receiver rail. I know a lot of flip up sights and removable ones are meant to be mounted on a handguard rail, but I want to mount it on the gas block rail if I can.

Want a front sight that can take standard sights (threaded pin kind). And an aperture rear sight. Removable, not flip up is fine with me.

Or should I just get a flip sight gas block?

Want to get everything straight before I buy anything.

 

[sacp81170a]

Not knowing if there is a standard height for gas block rails, there are advantages to mounting front sights on the gas block. The first is that you increase your sight radius (the distance between the front and rear sights) vs. mounting on the hand guard. On a shorter weapon, sight radius can be a critical element in precision shooting, more = better. Another advantage is that, unless you're using a rock solid hand guard, there's less chance of torquing the front sight out of alignment with attachments, pressure on a front vertical grip, etc.

I'd put the flip up on the front gas block and check to see if you can zero at 25 yards. If you can do that, you're good to go. If you don't have enough elevation or depression on the front sight to get zeroed, it's the wrong height. Most AR rear sights are coming with elevation adjustments now, so after you get the elevation right on the front sight, you shouldn't have to touch it ever again. I'd check with the manufacturer and see what they recommend, but I'd definitely go for mounting on the gas block.

 

[WNC Seabee]

I have an M&P 15OR and mounted a Troy folding front sight to the gas block rail. I had to raise the front sight post a LOT to get zeroed at 50 yds, but it got there. Prior to the Troy, I had mounted a UTG front sight and did not have enough post height to get on target.

On the Bushmaster web site, they offer a "tall" replacement post (just the threaded post, not the entire base/post assembly) that I'll likely end up getting. http://www.bushmaster.com/products.asp?cat=21

 

[New Mag]

Yankee Hill YHM-9584 is a front flip up designed for gas block mounting.

Just put a set on my Rock River Yesterday.

 

[HeavyDuty]

I'm using Mangonels - the front has two positions, one for gas block height and the other for handguard. They work well.

 

[Aka Zero]

The mangonels look pretty cool. Also looked at yhm. They have a fixed removable sight. And some nice aperture sights.