trouble with sights

[Omega13device]

I also fail to understand how raising your FSP will lower you POI?

Um, because it does?

[Merc1138]

I fail to understand how the rear sight would affect height. I also fail to understand how raising your FSP will lower you POI?

Really?

Ok, look at a gun from the side. Any gun, AR, 1911, glock, whatever.

Draw a line from the center of the bore at the back of the barrel straight out of the barrel like a laser.

Now draw a line from the top of the rear site to the front sight and keep it going forward like a laser as well.

Notice something yet?

What happens if you make the front sight shorter and draw the same line? You need to bring the front of the gun higher to keep that sight line at the same angle. What happens if you might the front sight taller? You need to lower the front of the gun to have that sight line maintain the same angle.

The line of the bore is what you're changing, not the line of sight.

DO you understand why raising the front sight lowers the POI now?

[Mac7504]

Really?

Ok, look at a gun from the side. Any gun, AR, 1911, glock, whatever.

Draw a line from the center of the bore at the back of the barrel straight out of the barrel like a laser.

Now draw a line from the top of the rear site to the front sight and keep it going forward like a laser as well.

Notice something yet?

What happens if you make the front sight shorter and draw the same line? You need to bring the front of the gun higher to keep that sight line at the same angle. What happens if you might the front sight taller? You need to lower the front of the gun to have that sight line maintain the same angle.

The line of the bore is what you're changing, not the line of sight.

DO you understand why raising the front sight lowers the POI now?

[negolien]

NO lol I still don't get it.. But then again my Back Up sights work fine and I have them adjusted so...

[2shotjoe]

where are the pics?

[Merc1138]

There is one thing to expand upon what I said, and that you have to remember that the bullet is going to travel in an arc. In the basic example I gave, your LOS and the bore only cross at one point. The reality is that the path of the bullet is not the same as that of the bore and will cross the LOS at 2 points(usually).

This is why when you're looking at a ballistic chart and the zero is at 50 yards, the POI for 10 yards is 2" low, and then you're 2" high at 100 yards, zero'd again at 200 yards, and then you're counting bullet drop after that.

[Merc1138]

NO lol I still don't get it.. But then again my Back Up sights work fine and I have them adjusted so...

Does it make sense now?

[Mac7504]

There is one thing to expand upon what I said, and that you have to remember that the bullet is going to travel in an arc. In the basic example I gave, your LOS and the bore only cross at one point. The reality is that the path of the bullet is not the same as that of the bore and will cross the LOS at 2 points(usually).

This is why when you're looking at a ballistic chart and the zero is at 50 yards, the POI for 10 yards is 2" low, and then you're 2" high at 100 yards, zero'd again at 200 yards, and then you're counting bullet drop after that.

Do folks zero based of what they shoot (yardage wise)? I've heard zeroing at 30 yards (iirc) is the baseline or something...??? I've still got to read up more on this, but things are getting clearer.

[Merc1138]

Do folks zero based of what they shoot (yardage wise)? I've heard zeroing at 30 yards (iirc) is the baseline or something...??? I've still got to read up more on this, but things are getting clearer.

Depends on what gun you're shooting, what caliber you're shooting, what you're shooting at, what your personal preference is, etc. A lot of people will start at 25 yards(or 20, 30, wherever you can put the target depending on your shooting range) just to get on paper with their new sights(it's easier to see the holes and measure how far off you are) and then zero it again at whatever their preferred distance is.

[Mac7504]

Depends on what gun you're shooting, what caliber you're shooting, what you're shooting at, what your personal preference is, etc. A lot of people will start at 25 yards(or 20, 30, wherever you can put the target depending on your shooting range) just to get on paper with their new sights(it's easier to see the holes and measure how far off you are) and then zero it again at whatever their preferred distance is.

Ahh, ok thanks.

[gemini1]

NO lol I still don't get it.. But then again my Back Up sights work fine and I have them adjusted so...

How about this?

[USMCUCLA]

So this is my sights setup. This is my first time using back up sights at any range over 36 meters. I dont know how accurate they really should be. I know with a full set of A2 sights you adjust the range on the rear sight before you start your BZO procedures and I was just thinking that maybe not having the ability to adjust the rear sight height on my current setup could be the problem. Still 2 feet high at 100 yards seems pretty excessive. Thanks for all the replys.

[Merc1138]

So this is my sights setup. This is my first time using back up sights at any range over 36 meters. I dont know how accurate they really should be. I know with a full set of A2 sights you adjust the range on the rear sight before you start your BZO procedures and I was just thinking that maybe not having the ability to adjust the rear sight height on my current setup could be the problem. Still 2 feet high at 100 yards seems pretty excessive. Thanks for all the replys.

Ok, so it's not some built in riser or something(figured it wouldn't hurt to eliminate all of the possibilities I could think of). I'm stumped. All of the ejected brass looked fine too?

[cavemanlrrp]

the magpul and most rear sights are made for f-mqrked FSB, you can buy a new front post, .040" taller to fix your prob

^^ This ^^

Google, F marked front sight base.

F marked FSB, for flat tops/ M4, is a bit taller than "standard" A2 FSB.

So you will need a little more up, up front to get your POI down. If you don't have an F marked. FSB.

Best
caveman

[ocabj]

NO lol I still don't get it.. But then again my Back Up sights work fine and I have them adjusted so...

For an AR or rifle with similar sights, you have to adjust your front sight post first when zeroing for the minimum range you will be shooting at, otherwise you won't maximize the rear sights elevation drum.

Let's say your minimum range is going to be 100 yards. Set target at 100 yards.

Bottom the rear sight. Come up about 6 clicks to remove any dead clicks (sometimes the first few clicks from the extreme end of the drum will be 'dead' ; won't be exact 1/4MOA or whatever increments).

Use a 6 o'clock hold for this step and not center hold since this will give you more leeway on the bottom end. Even if you shoot center hold, there are cases where you might need 6, and setting the front sight in this method while using center hold could result in not enough down adjustment for a 6 hold at the minimum zeroing range).

Anyway, with 6 o'clock hold take a shot. Adjust the front sight accordingly. You will want to adjust the front sight post up/down until the point of impact is either dead on elevation wise or just under. In the case where you are using a National Match (tapered) front sight post, you will have to to turn the front sight post in full revolutions. So in this case, keep adjusting to where the point of impact is just below center elevation (and the next rev down will result in the point of impact going above dead center elevation wise).

Once that is accomplished, adjust the rear sight accordingly. Take shot, reconfirm zero. Click the rear sight down and count the number of clicks. Write that down. Now you have your 6 o'clock minimum range zero (in this case, 100 yards).

This method of adjusting the front sight post elevation now gives you maximum usage of your rear sight elevation adjustments.