Newbie scope adjustment question

[Harmonica]

If I have my rifle zeroed at 100 yards and the bullet drops 9 inches when shooting at a 300 yard target, do I adjust my scope up 3 MOA to raise the POI back up to (or at least near to) POA? If it drops 24 inches at 400 (100 yard zero), do I adjust up a total of 6 MOA so I can hold on the center of the target?

I'm getting a scope for my AR soon and I want to make sure how this works before cranking on the knobs at the range.

[MostlyHarmless]

That's how it works.

And then you write these notes out nearly on a post-it note, and you cover it on both sides with packing tape. Fold it up, stuff it into your pistol grip, and cover it with one of those DPMS grip plugs (or similar). Of you could write it all down really tiny, and then tape to the inside of your flip up rear scope cover.

[Unbridled Liberty]

You would do well to attend an Appleseed KD clinic.  There are already some on the calendar in Tennessee for 2015: http://www.appleseedinfo.org/search-states-display.php?qstate=TN&statename=Tennessee

UL

[hawkhavn]

Harmonica,

The first thing you will want to do is confirm that your scope adjustments are what is stated.
Fire a 3 shot group, adjust the scope up 10 MOA.
Shoot another 3 shot group, confirm that your second group is, in fact, 10 MOA up from the first.
Repeat for lateral adjustments.
Don't be surprised if it isn't. Just know what your scope MOA adjustments do.

Good luck!
HH

[Rayne]

Harmonica,

The first thing you will want to do is confirm that your scope adjustments are what is stated.
Fire a 3 shot group, adjust the scope up 10 MOA.
Shoot another 3 shot group, confirm that your second group is, in fact, 10 MOA up from the first.
Repeat for lateral adjustments.
Don't be surprised if it isn't. Just know what your scope MOA adjustments do.

Good luck!
HH

One thing HawkHavn forgot is to tell you was to always aim at the same point.  For example put a five square up and aim at the bottom left target during all your shoots. 

[AAOptics]

I do box testing a touch different that a lot of folks.  My box test takes 10 shots total (assuming I knew I did it right on all shots).

Sight the gun in.

Buy get one of those targets that has a square in the center, and all 4 corners.  On the ones I buy the corner square is 5 inch's up, and 5 inchs right of center.  I always aim center bull.

I put the target at 25 yds, and put 1 bullet center bull.

I dial up 20MOA and right 20MOA, and shoot 2 shots.

I dial down 40 MOA and fire 2 shots.

I dial left 40 MOA and fire 2 shots.

I dial up 40 MOA and fire 2 shots.

I dial right 20 MOA and down 20 MOA and fire 1 shot.

You will notice when doing this test that 80ish% of the scopes on the market will not have the first, and last shot touching (or within shooter's limitations).  The reason being is a lot of scopes track ok when there is no pressure on the errector near the mechanical center, but when you get the turrets on the edges of their internal travel they show their true colors.  A lot of folks say "it doesn't matter what they do as long as you know what they do".  The first thing is most scopes that do not track loose there POI because of inconsistent clicks (IE x click is 1/4MOA, y click is 1/8th MOA, z click is 1/2MOA) this makes consistency impossible.  Unless your going to try and track what individual clicks do to your POI which is to much remembering for me.

The ones that do dial consistently wrong is a little better, but for me, I'm a huge fan of simplicity, and uniformity.  I dont want to go and dial range, and try to remember what this specific scope does.  I want to read the top of the turret, and know the bullet will do what I tell it to.  Tracking scopes usto cost a fortune, but today you can buy them for as little as 100 bucks IF you buy the right scopes.

[armaborealis]

I would like to throw out some other solutions to the quandry as well.

1)  BSZ.  You can exploit the Battle Sight Zero of your rifle.  Most AR-15s, if zeroed at 25 yards, will tend to be high from 25-300 and then on again around 300 yards.  You can measure the height above bore for your scope and plug the numbers into a ballistics calculator to be sure.  Thus, no fiddling at the range.  Just "aim for the tenders" and hold about 7" low out at 100-200 yards.

If you zero at 50 yards, the crossover point will be around 200, and you'd be low around 300, so at 300 you'd just aim a little high.

2)  Many scopes come with a reticle that lets you calculate the drop.   For example, there are some scopes with built in M193 5.56 ball ballistic drop compensation.  Just put the crosshair marked "300 yards" on the target and you're good to go.  An inexpensive example is the Primary Arms ACSS line.  Others will be marked off in increments (often a mil increment).  1 mil = 3.4 MOA.  You would just hold one mil dot high and be darn close to "on" if your comeup is 3 MOA.

All of the above assumes you're looking for rifleman's accuracy to make hits on those D-type silhouettes.  If you're doing more precise work then you may indeed need to dial come-ups.

[Harmonica]

Thanks for the info. This will be for KD type shooting 100 - 400 yards. Not striving for pinpoint accuracy. Is a 1-4 variable OK for that or do y'all suggest more magnification? I was thinking about a 1-4 VX2. I really don't want something huge on there.

[Del]

1-4x will work just fine.

[Unbridled Liberty]

What Del said.  I really like my 1X EOTech 512.  Even with my astigmatism, I can put the 1 MOA dot wherever I like on a D target at 300 yards, and with a little holdover, I can make consistent hits in the black at 400.

UL

[slim]

Thanks for the info. This will be for KD type shooting 100 - 400 yards. Not striving for pinpoint accuracy. Is a 1-4 variable OK for that or do y'all suggest more magnification? I was thinking about a 1-4 VX2. I really don't want something huge on there.

4276vette up there is a Vortex dealer. Go direct with him. He'll set you up with everything you need and nothing you don't...at the best value in the industry.

[AAOptics]

Thanks for the info. This will be for KD type shooting 100 - 400 yards. Not striving for pinpoint accuracy. Is a 1-4 variable OK for that or do y'all suggest more magnification? I was thinking about a 1-4 VX2. I really don't want something huge on there.

On a KD type shoot your looking for MOM (minute of man) shooting, not MOA (minute of angle).  On a MOM type rifle a 1-4 is perfect.  In fact, I have 2 MOM type rifles, and both wear a 1-4.  If you get a quality 1-4 it will do everything a red dot with magnifier will do, do it better, be more durable, all while doing it cheaper.  The only dis advantage is a 1-4 has eye relief (some have absolutely huge eye box's, some don't).  If your head is close to the right spot having eye relief will be a mute point, if you think you will need to hang upside down, and shoot underneath a car at some point you should look the red dot with magnifier route.  Personally Ive never had to shoot under a car so I stick with a 1-4.

[Shooter30-06]

I agree with the approach of armaborealis. In preparation for attending a KD this year I purchased a Nikon P-223 scope which has the 400 come-up on the reticle.  I intend to compensate at 100 and 200 yards by holding under COM.  I have been practicing with a 25 meter standing target at 25, 50, 75 and 100 yards and have shot expert that way.  The fixed 3 power scope on the P-223 works just fine.  I can see the target but not so much that I fuss the shot.

[floydf]

If I have my rifle zeroed at 100 yards and the bullet drops 9 inches when shooting at a 300 yard target, do I adjust my scope up 3 MOA to raise the POI back up to (or at least near to) POA? If it drops 24 inches at 400 (100 yard zero), do I adjust up a total of 6 MOA so I can hold on the center of the target?

I'm getting a scope for my AR soon and I want to make sure how this works before cranking on the knobs at the range.

When thinking about the divergence between POI and POA over different distances, it's real important to think in MOA.  The standard "come-ups" we use (in DFW) are 3,3,3,4, which translated means that from a 100 yd zero, the POI will drop 3 MOA at 200 yds, and from a 200 yd zero, the POI will drop 3 MOA at 300 yds, and so on from 300 to 400 and from 400 to 500.

Do the math in MOA, and then convert to inches at the specified distance.

Using these standard come-ups, from a 100 yd zero, the POI at 300 will be 3 + 3 = 6 MOA low, which at 300 yds is 18 inches.

With a 300 yd zero, the POI at 100 yds will be 3 + 3 MOA high, or 6 inches high.

You need to keep thinking about this until it makes sense.  And keep doing the math until it gets to be more or less auto-math.

These are just rule of thumb to get you on paper.  Actual come-ups depends on the rifle, scope, type and size of rings, and ammo.

All you need to effectively shoot Appleseed KD distance is to know your 25m zero, your 300 yd zero, and the come-up to go from 300 to 400. 

And, you do need to be able to effectively do the box drill at 25.  We do the simple one, usually on Sunday AM, where we ask the shooters to raise the POI 10 MOA, then move it 10MOA to the left.  Except that if we can get 2 out of 20 to come anywhere close on the first iteration it's a Good Sunday   So actually getting 10 MOA up and 10 MOA to the left (or right) usually takes four, five, or six five round groups.

Whether you adjust the scope in the field or just use a fancy reticle depends on the scope.

Burris, for instance, has an AR scope with bullet drop compensator reticle, and miserable little adjustment dials that no on in their right mind would ever adjust in the field.  So you pretty much have to zero at 100, and then use the reticle.  I pretty much hate it, because there is so much going on the reticle it's hard for me to get a clear sight picture.  That's me.

I prefer the old fashion duplex cross-hairs, and you pretty much need to adjust these in the field.  In that case, you need to be really proficient at the box drill, need to know really how many clicks per MOA on the scope, and need to have some base zeros marked on the scope.  Because, especially on primitive ranges like the ones we use, where you shoot, then walk 300 or 400 yds before you find out where the holes went, it's really easy to get all wonkerjawed with scope adjustments.

[slim]

As others have said, 1-4 isn't too much for 400 yard shooting. Personally, I prefer a fixed power because it's one less thing to worry about and in the field, the less you have to worry about, the better. For that reason, I use a 3.5 fixed power with a BDC. I simply line up the right stadia line (which is also fool proof because it's the only one that "fits" the target) and squeeze.

If you're not going with a BDC, then using the Battle Sight Zero is the way to go. You can hold at 6 O'Clock for 100, 200, 300 yard targets and simply hold on the top of the head for the 400. Easy peezy, and can be done with a cheap duplex reticle scope or iron sights.

*Shooting KD with a scope I'll recommend holding the lateral line at 6 instead of center. Makes it a lot more consistent and repeatable since you're only shooting "the gray area" and it's a lot harder to hold center at 300 yards with that black line "somewhere" in the middle of that black target. You can be absolutely sure it's at the bottom every single time.

we ask the shooters to raise the POI 10 MOA, then move it 10MOA to the left.  Except that if we can get 2 out of 20 to come anywhere close on the first iteration it's a Good Sunday   So actually getting 10 MOA up and 10 MOA to the left (or right) usually takes four, five, or six five round groups.

This is why I prefer the "box drill" to be a unit of clicks as opposed to a unit of inches or moa. In simple algebraic terms we're solving for X and we don't know any of the values. We can't guarantee our adjustment will move 10 moa. We can't even guarantee it will move 2.5 inches. But, we can guarantee it will move 10 clicks because we can count the 10 clicks.

Then, when we go downrange, we simply do the math and solve for X. "10 clicks on my scope moved my group X inches. X divided by .25 = _moa/click."

Another benefit of doing clicks instead of MOA or Inches is the iron sight shooters can solve the simplified equation as well. Instead of guessing their front sight is 1.5moa/click and rear is .75moa/click then trying to get 10moa out of 6 clicks they can click it 10 times, measure, and get an exact moa value for each click.

Those of you using 3 moa or 5 moa or even 10 moa to do your box drill will run into problems at public events because many shooters are still shooting 6 or even 8 moa groups. Shooting a 7 moa group and going up 10 moa to shoot another 7 moa group doesn't necessarily show two distinct groups at 25 yards. We had a Shoot Boss once show us the box drill moving her (yes, I said HER!  ) groups 4 moa up, right, down, left and back up again and it was awesome! Problem with doing that as a point of instruction was my first group covered her whole box drill!

Point of the box drill is to ascertain the click value of your sights. Doing it in a large enough manner with simple enough numbers to do it quickly and gain usable data is the goal. If it takes four or five times of doing it, that's fine for a day at the range by yourself. But doing so at a KD event helps that time monkey take a big bite of your backside.

I recommend doing 40 clicks on scopes and 10 clicks on irons. Also, doing three shot groups at each "corner" will cut down on flyers and unusable/confusing data. (Plus smack that time monkey a bit more!) On cheap scopes that say "1 click = 1/4" @ 100" doing 80 clicks isn't too many. Gives the shooter more room to work and often makes the math easier to convert.

I sure wish they would've told me back in algebra and geometry this is why we were studying. I would've paid SO MUCH MORE attention!

....and now I'm ready to go shoot!