Warning

 

Close

Confirm Action

Are you sure you wish to do this?

Confirm Cancel
Member Login

Posted: 1/20/2008 12:32:21 PM EST
Hey all- I just got a flip up front sight that clamps onto my gas block (varmint-style AR), and I was wondering what the easiest way is to make sure it's aligned with the rear sight and muzzle, before actually doing live fire testing.

There's a little bit of left-right give in "where" you clamp it down on the block, which is why I'm asking.

Thanks!
-BB
Link Posted: 1/20/2008 1:04:34 PM EST
When I installed my YHM front sight which clamps around the barrel, I did the following.

- Installed the sight in the correct location on the barrel, loose enough that I could rotate it.

- Placed the whole upper receiver inverted on my kitchen counter top which I trust to be a pretty level and smooth surface. At least for this task.

- With the upper receiver laying inverted, the rear of the receiver lay flush with the counter. Then it was simply a matter of rotating the front sight until both ears of the sight also sat flush on the counter.

- From there I tightened the hardware.

You might be able to use a similar process with the installation of your sight.
Link Posted: 1/20/2008 1:24:59 PM EST
Damn, I love simple. I'll try that on the build I'm getting ready for.
Thanks
Link Posted: 1/20/2008 1:28:24 PM EST
Not a problem.....glad to help.
Link Posted: 1/20/2008 1:29:47 PM EST
What did you have on the rails at that point? mini risers? An A3 carry handle? Because without anything, the front sight is the highest point, even when down.

Thanks!
Link Posted: 1/20/2008 1:33:07 PM EST
I've wondered about this too...always figgered a bit of string/dental floss tied round the rear sight and then looped round the front should work.

But know I've never done this (yet anyway)
Link Posted: 1/20/2008 1:35:51 PM EST

Originally Posted By BigBrother:
What did you have on the rails at that point? mini risers? An A3 carry handle? Because without anything, the front sight is the highest point, even when down.

Thanks!


Well, that’s where you’ll have to use a little bit of ingenuity!
Link Posted: 1/20/2008 1:37:04 PM EST
i put a level on mine receiver "flat top" or you can go off the rail if its straight, and then put another level on the Flip up front sight, and make sure the bubble is in the same spot on both levels.
Link Posted: 1/20/2008 1:37:43 PM EST
I just installed one myself.

Upper receiever held in receiver block in vise.

With the sight folded, I was able to lay a 12" scale on the flip up and reach the rails on my flattop. It was quite easy to see and correct the cant.

Works with a carbine and midlenth, you would need a 18" scale for a rifle.
Link Posted: 1/20/2008 2:07:42 PM EST
Thanks QUIB, just did it.

This does raise a question though- since I'm new to AR shooting- how "spot on" are most hard-point front sights on ARs? Meaning, with a permanently attached front sight on the gas block, like with a standard A2, do you think they take extra pains to line up the post with the rear aperture to exacting standards, or does "close enough" suffice when shooting, even long distance?

Thanks,
BB
Link Posted: 1/20/2008 2:14:17 PM EST

Originally Posted By BigBrother:
Thanks QUIB, just did it.

Glad to help.

This does raise a question though- since I'm new to AR shooting- how "spot on" are most hard-point front sights on ARs? Meaning, with a permanently attached front sight on the gas block, like with a standard A2, do you think they take extra pains to line up the post with the rear aperture to exacting standards, or does "close enough" suffice when shooting, even long distance?

Thanks,
BB



If you take the necessary steps, as you just did, to ensure your sights are true to the rifle, then you’ve most likely eliminated some of the additional windage that might have been necessary during zero. Windage you might have had to add if you hadn’t lined up the sights.



Link Posted: 1/20/2008 2:16:21 PM EST

Originally Posted By QUIB:

Originally Posted By BigBrother:
Thanks QUIB, just did it.

Glad to help.

This does raise a question though- since I'm new to AR shooting- how "spot on" are most hard-point front sights on ARs? Meaning, with a permanently attached front sight on the gas block, like with a standard A2, do you think they take extra pains to line up the post with the rear aperture to exacting standards, or does "close enough" suffice when shooting, even long distance?

Thanks,
BB



If you take the necessary steps, as you just did, to ensure your sights are true to the rifle, then you’ve most likely eliminated some of the additional windage that might have been necessary during zero. Windage you might have had to add if you hadn’t lined up the sights.





Ahh, I think you're touching on my main point- given a standard A2, if you were to shoot the thing on a clear, wind-free day, would you expect to have to ever adjust the windage knob as you shot out at 100, 200, 300, and then 600y distances?
Link Posted: 1/20/2008 2:21:59 PM EST

Originally Posted By BigBrother:
Ahh, I think you're touching on my main point- given a standard A2, if you were to shoot the thing on a clear, wind-free day, would you expect to have to ever adjust the windage knob as you shot out at 100, 200, 300, and then 600y distances?


Once my sights are zeroed, I never touch the windage.
Link Posted: 1/20/2008 2:38:36 PM EST
[Last Edit: 1/20/2008 2:39:23 PM EST by BigBrother]
Alright, not to nit pick, but something doesn't make sense- I'm trying to learn here, so bear with me.

Let's talk in terms of basic trig- you have one line- that of the barrel/muzzle. On a wind-free day, that's the straight path the bullet will take out to infinity.

Now, you're trying to get your rear aperture and front post to line up with that line. And here's my confusion point- unless those two are perfectly in line with the barrel, won't a 100 yard zero *not* be the same as a 600 yard zero, windage-wise?

Put another way, if the front post and the muzzle don't line up perfectly with the barrel, won't a windage adjustment done on the rear sight only work at certain distances?

As you can tell I haven't done this before (still waiting on my ammo ), but I'm trying to learn as much as possible (hence my original question on adjusting the front sight.)

Thanks!
-BB
Link Posted: 1/20/2008 11:15:27 PM EST
Having played with several front sight changes I have liked the following method.

Remove the old front sight.
Place the upper receiver in vice using the appropiate clamps.
use a laser (I use one of these Craftsman for hanging pictures and stuff) and verify the gas port lines up with the rear sight.
If all is aligned I drop the new front sight on and align the post to the laser.

I have found the above to work quite well and with minimal adjustment at the range.
Link Posted: 1/21/2008 2:42:41 AM EST

Originally Posted By BigBrother:
Alright, not to nit pick, but something doesn't make sense- I'm trying to learn here, so bear with me.

Let's talk in terms of basic trig- you have one line- that of the barrel/muzzle. On a wind-free day, that's the straight path the bullet will take out to infinity.

Now, you're trying to get your rear aperture and front post to line up with that line. And here's my confusion point- unless those two are perfectly in line with the barrel, won't a 100 yard zero *not* be the same as a 600 yard zero, windage-wise?

Put another way, if the front post and the muzzle don't line up perfectly with the barrel, won't a windage adjustment done on the rear sight only work at certain distances?

As you can tell I haven't done this before (still waiting on my ammo ), but I'm trying to learn as much as possible (hence my original question on adjusting the front sight.)

Thanks!
-BB


Windage is right-left and shouldn't be effected by distance, wind perhaps.

Elevation is effected by distance however.

If the front sight post is off, requiring windage adjustment, you already corrected for it at shorter ranges, regarding windage.

At long range, bullet drop, given it's particular ballistics, is important.
Link Posted: 1/21/2008 3:07:24 AM EST
Windage adjustment shouldn't change at any distance once dialed in. Thats not factoring wind. I've never changed my windage once it's on at 50.
Link Posted: 1/21/2008 5:07:30 AM EST
Windage adjustment makes the sights parallel to the barrel at zero. That makes range irrelevant in this theoretical windless situation.

Elevation zero converges with the barrel at a point down-range (and not necessarily at the same place as the bullet will hit).

That's because you want the barrel to be pointing up just a little when the sights are level so the bullet (which travels in an arc) will hit where the sights are pointed. Because the bullet doesn't arc side to side the windage is the same for all ranges.
Link Posted: 1/21/2008 9:10:28 AM EST

Originally Posted By Z09SS:
Windage adjustment makes the sights parallel to the barrel at zero.


Ahh, I think you may have finally solved it for me- so what you're saying is, even *if* the front sight, say, is a hair off set from the barrel, you line up the rear with it, thereby creating a line of sight that is parallel to the barrel. So it *may* be a mm off, horizontally, but it's still parallel and thus, only a mm off at impact point as well (and thus negligible?)

Thanks,
BB

Link Posted: 1/21/2008 9:50:12 AM EST
Use a level...


I'd prefer to use the same level for the front and the back as opposed to two different levels at the same time. Sometimes the bubbles behave differently in different levels.


- BG
Link Posted: 1/21/2008 12:43:31 PM EST
I think your making this more complicated than it really is. Your trying to “over think” zeroing your sights.

Even if your front sight was slightly off windage wise (FSB cant), if you were to zero that rifle at a given distance, it would remain zeroed throughout the entire range.

Once your point of impact is aligned with your point of aim during zero, your windage will not change as your engagement distance increases.

Your elevation will of course change, but in a perfect environment (for the sake of discussion) your windage would not change.
Link Posted: 1/21/2008 1:07:19 PM EST
I thought. If your front post is not in direct alllignment with your barell's bore then you will have to adjust the windage at longer distances than you dialed in at. Right?
Link Posted: 1/21/2008 1:12:31 PM EST
[Last Edit: 1/21/2008 1:13:15 PM EST by BigBrother]
<delete>
Link Posted: 1/21/2008 2:00:59 PM EST

Originally Posted By RallySoob:
I thought. If your front post is not in direct alllignment with your barell's bore then you will have to adjust the windage at longer distances than you dialed in at. Right?


No. Once you sight in, the front and back sight are aligned with the bore. As long as the sights are centered above the bore, you will be fine for windage. If you cant the rifle while you sight in (sights aren't centered above the bore), then your sight in will be different for different ranges. I think you guys are mistaking canting the rifle for canting the sight.

It is the same with a scope. The cross hairs could be tilted at a 45 degree angle, but if properly sighted in with the center of the scope directly above the bore, it will work fine as far as the rifle can shoot. This arrangement would make adjusting a scope much more difficult. If you raise or lower the POI in a scope and the windage changes, it means the vertical line is not straight with the bore.
Top Top