Carry handle driving me crazy on AR556!-RESOLVED

[Jambo]

What "fixed front sight with a built-in gas block" goes on an A1 upper?
What "fixed front sight with a built-in gas block" goes on an A2 upper?
What "fixed front sight with a built-in gas block" goes on an A3/A4 upper?

The A2 style non marked, the A2 style non marked, and A2 style F marked respectively?
Did all the A1 rifles have an A2 style front sight base on them before the A2 upper was even produced?

No.
The A1 style had a round sight with five detent points.
The A2 style is the same as an A1, except the sight is square and has four detent points. The only difference is in the sight itself.
The A3/A4 is the same style as the A2, except it's taller to match the removable carry handle sights on the flat top upper. The sight itself is square with four detent points. It should also be "F" marked to indicate it matches the flat top sights.

 

[CQB27]

No.
The A1 style had a round sight with five detent points.
The A2 style is the same as an A1, except the sight is square and has four detent points. The only difference is in the sight itself.
The A3/A4 is the same style as the A2, except it's taller to match the removable carry handle sights on the flat top upper. The sight itself is square with four detent points. It should also be "F" marked to indicate it matches the flat top sights.

You are 100 percent correct.....but we are talking about the front sight base.....not the front sight post.
The front sight bases are all the same height when measured from top to bottom......the only exception being the F marked front sight base has the shelf for the front sight post machined at a height of 1.98 inches above the barrel as opposed to the standard which has the shelf machined at 1.94 inched above the barrel, assuming the barrel diameter is the standard .750 inch at the front sight base.

Every dimension of all forged front sight bases is the same, with two exceptions: 1.) the barrel mounting points are of different diameters (the smaller thin barrels are .625 inches in diameter, for standard barrels .750 inches) and the front sight post shelf height (1.98 for F marked, 1.94 for standard). While the A2/A3/A4 front sight post differs from the A1, there is no A2 style front sight base. There are F marked front sight bases and standard front sight bases.

We agree that the front sight base on an A1 upper and A2 upper are identical when the front sight post is removed. If you put a square, 4 detent front sight post in an A1 upper front sight base is it suddenly an A2 style front sight base? If you take the round, five detent front sight post and put it in the A2 upper front sight base does it become an A1 front sight base? What if you put the round, five detent A1 front sight post in a F marked front sight base what does it become? An A1 style F marked front sight base?

Front sight posts differ between the A1 and A2/A3/A4 upper. Front sight bases differ in front sight post shelf height between the F marked and standard front sight bases. There is no such thing as an A2 style front sight base.

 

[grabbin' asphalt]

Yeah, I'll clarify that. Didn't mean at Bullseye, just mean to hit the bullseye. My phone did capitalize it, so I see the confusion.

Ironically, the gun was purchased at Bullseye, haha.

Yup the Capitalized got me!! Lol

 

[Bennyboy]

Thanks everyone, I just lowered the FSP back down to work with the BUIS so at least it's shootable till I get it sorted. It shoots about 3 inches high AT FIFTEEN yards with this setting and the carry handle, meaning it's probably a foot or more high at 50 yards. So to recap, I'm pretty sure it's 1 of 3 things:

1) Carry handles are too tall. I feel this is unlikely because Milspec (what my gun supposedly needs) is already the taller of the two available heights. What are the chances I got two CHs that are neither Commercial or Milspec height?

2) Ruger somehow put the wrong height FSB on my gun. While I don't think this is very likely (they supposedly make them in house and be AR556 is the only gun with an A2 style sight), I guess it could be an internal misunderstanding on A2 height vs A2 style, etc. Main thing that supports this is the fact that the provided BUIS are shorter than the carry handles and Magpul (who I believe make them for Ruger) clearly state on their website they are for A2 height FSBs, which are the ones that are 0.04" shorter.

3) Ruger simply has too short of a front sight POST. This is probably most likely as it seems the easiest thing to do, and most people don't run carry handles these days so they never notice since it will zero with the BUIS. It simple runs out of adjustment before it'll zero with a CH.

I'm now trying to find an extended FSP but not having a lot of luck. Anyone know the standard height? The old Bushmaster part number everyone talks about is discontinued.

 

[Radar363]

Is there such a thing as a fixed front sight base without a built in gas block as far as ARs are concerned? What does "fixed" mean? I would call it a Daniel Defense F marked front sight base. Just because Brownells is as confused about the "A2" nomenclature doesn't make them any more informed than Ruger.

Like I stated before Ruger's "A2- style F-height allows co-witness with many optics" front sight statement is completely nonsensical. There is no standard or specification for an "A2" front sight base and the height of the front sight base, F/1.98 inches or standard/1.94 inches, has zero to do with co-witnessing an optic.

I have a couple of BCM Kino uppers, 12.5" barrel with carbine gas system but FSB is out at mid-length.

 

[Plinker66]

Here's a round one fer five bucks

https://shop.windhamweaponry.com/products/9349056-mod

 

[Bennyboy]

Here's a round one fer five bucks

https://shop.windhamweaponry.com/products/9349056-mod

Thank you!! Google wasn't bringing up anything. Placing order now.

 

[CQB27]

I have a couple of BCM Kino uppers, 12.5" barrel with carbine gas system but FSB is out at mid-length.

Yeah, I have had that type set up too, and the forward front sight base was drilled for the barrel gas port and gas tube. It is identical, gas chamber wise to the low profile gas block under the hand guard.....just unused.

I guess some refer to the assorted clamp on rail front sights that don't fold as "fixed", and they don't have gas chambers. But a "fixed" removable front sight base seem a little nonsensical too.

 

[Bennyboy]

Got the taller front sight post in today and it allowed just enough adjustment to work for my 50 yard zero. I'm now certain that the Ruger front sight base is NOT F marked height because even with the +0.04" sight post, it's still at the limit of adjustment.

Anyway, thanks for all the help guys. Glad to have it resolved. Oh, and the pic is my first two shots fired at 50yards. I thought I missed the whole target till I walked to it.

 

[greg vess]

I was going to ask you if your gas block was the same height as the rail on your upper. They make a front sight post just for low profile gas blocks. I thought about that when I first read your post. I just thought you had a handle on that ( no pun intended ).