Rifle Scopes How do YOU level your optic?

[Jerry45]

Sit small level on the rail, clamp other level on barrel. Match bubble in level clamped to barrel with bubble on rail. Mount rings and scope, place small level on scope cap match bubble on scope to bubble clamped to barrel. Torque scope in rings. LEVEL!

 

[coues7]

I use feeler gauges.

 

[Ledzep]

I put a level on top of the elevation turret (remove as much of the turret as I can to get to the "guts"). Then I level that off with gravity. Install the level that clamps onto my scope, and level it to the elevation turret.

Scope is then level with gravity in the place that adjusts for gravity. Then I mount the scope while holding the rifle to get the correct eye relief and rifle "cant" to fit me best.

I see a lot of paranoia about having the scope not DIRECTLY over the center of the bore. Not justified, IMO. I just posted about this in the "ELR" section, but do the math.

For example, say your scope is 1 full inch to the left of your bore center when the scope is level. You can do a 100yd elevation zero, and a 200yd windage zero. Watch what happens.

100yd, POI is .5" right of POA, 200yd it's dead on, 300yd, POI is .5" left of POA, 400yd, POI is 1"left, 500, 1.5" left, etc. 1000yd, your POI is 4" left of POA. So less than 1/2 MOA offset at 1000yd, and smaller the closer in you are... That does not include spin-drift, which would cancel out some (all?) of that at longer ranges.

The physical offset of 1" left of bore pales in contrast to a 3-5 degree cant in the elevation turret.

edit: I should add, I think it's pretty important in the long-range game to have a level on your scope. For the longest time I thought I was capable of eyeballing it and consistently keeping things level. After trying my first scope level, what I found was that I was consistent... Consistently canting to the right. Immediately I looked back at my LR experiences and it became very clear. I had a TON of rounds impact to the right of my POA at 600-1000yd, even when the wind was blowing right to left. Your gear is only as accurate as you set it up.

 

[M1Amen]

Correct me if I'm wrong, but it doesn't matter so much that the optic and rifle are leveled together, just that when you fire, it's important that your optic is level. The bullet will always fall toward the center of the earth, so as long as your reticle is level when you fire, you should be good to go.

Some people go so far as to mount their optic at an angle so that when they shoulder their rifle the optic is level (and the rifle is cocked at an angle).

Actually it matters a great deal. The effect is the same as canting the rifle and as range increases, you will see a greater and greater divergence from your point of aim. You absolutely want the bore and the reticule true to each other. If they are not, then as range grows, you will be adjusting for windage (even under a hypothetical purely windless condition).

 

[fw707]

I used feeler gauges to get it leveled to my rifle... I then setup a plumb bob somewhere in the distance, setup my rifle so my scope reticle is aligned to the plumb bob... set my bubble level on my scope to be level... then I'm done.

My reticle will always be level to the world as long as the bubble says it's level. I place the level above left of the scope so if I look through the scope with both eyes open (right eye dominant), my brain superimposes an image of the bubble level into the actual scope so I can watch my target and see a semi blurry version of the bubble level at the same time.

That's exactly the way I do it.

 

[M1Amen]

Not sure if this is true of not but I was told that barrels are angled slightly upwards and that's why there a rise in the trajectory before it starts to drop. Otherwise it would start descending the instant it leaves the barrel.

barrels are angled upward to the extent necessary to have the bullet reach a certain distance.

 

[sentry1]

Not sure if this is true of not but I was told that barrels are angled slightly upwards and that's why there a rise in the trajectory before it starts to drop. Otherwise it would start descending the instant it leaves the barrel.

Err..? The bore should be co-linear with the chamber, no? The angle of the barrel would be the whole gun being elevated to adjust the ballistic trajectory of the bullet to get it to the target.

Keeping it (somewhat) simple, with no drag forces factored in:

 

[J Mack]

I use an adjustable parallel, same principle as the feeler gauges but more range for tall rings or AR mounts.

 

[jonesy]

Actually it matters a great deal. The effect is the same as canting the rifle and as range increases, you will see a greater and greater divergence from your point of aim. You absolutely want the bore and the reticule true to each other. If they are not, then as range grows, you will be adjusting for windage (even under a hypothetical purely windless condition).

Look at some of the math I did in a previous post. I concluded that any POI shift due to rifle cant would be negligible at long range. Having your scope canted, on the other hand, would lead to drastic errors (if you're holding wind/elevation). Here is the math:

1.25" scope height, 5 degree cant, and 300 yard zero. What is your miss at 1000 yards with these parameters? You'd be hitting 0.25" to one side. The side you hit depends on which way your scope is canted.

As you can see, even misreading wind by 0.25 MPH would lead to a larger margin of error in your POI. Basically, all that is needed is to eyeball your scope level to your rifle when you mount it (mostly for ergonomics), then after you mount it, you need a level on your scope for longer shots to make sure your scope isn't canted to gravity. Relative scope-rifle cant is really a non-issue.

 

[Ledzep]

Actually it matters a great deal. The effect is the same as canting the rifle and as range increases, you will see a greater and greater divergence from your point of aim. You absolutely want the bore and the reticule true to each other. If they are not, then as range grows, you will be adjusting for windage (even under a hypothetical purely windless condition).

It is not the same.

If the scope is level, and the rifle is canted, there is a fixed ratio of offset, and that offset is small (well below 1/2MOA in normal circumstances). Outside of the theoretical, with any kind of wind, it becomes negligible.

If the scope and rifle are square to eachother, and both are canted, there is a trig problem depending on how far away and how canted the scope/rifle is. The effect of canting the scope is Grossly more than that of having your bore not directly under the scope. For example, a 5 degree cant is usually going to be around 2-4 MOA beyond 500yd.

 

[jonesy]

It is not the same.

If the scope is level, and the rifle is canted, there is a fixed ratio of offset, and that offset is small (well below 1/2MOA in normal circumstances). Outside of the theoretical, with any kind of wind, it becomes negligible.

If the scope and rifle are square to eachother, and both are canted, there is a trig problem depending on how far away and how canted the scope/rifle is. The effect of canting the scope is Grossly more than that of having your bore not directly under the scope. For example, a 5 degree cant is usually going to be around 2-4 MOA beyond 500yd.

Yes, exactly what I've been trying to say. Good explanation!

 

[Ledzep]

Here's some Michael Angelo quality artwork to give you a visual. As you can see with the canted optic, the distance it goes to one side or the other is greatly dependent on how far away (how much you crank on the elevation turret), and how tilted the rifle is. It will be relatively relative to the trajectory of your round in the X,Z plane, but not directly because some of the adjustment is side/side, and some of it is up/down. Hopefully that confused you.

 

[BigJimFish]

Here's some Michael Angelo quality artwork to give you a visual. As you can see with the canted optic, the distance it goes to one side or the other is greatly dependent on how far away (how much you crank on the elevation turret), and how tilted the rifle is. It will be relatively relative to the trajectory of your round in the X,Z plane, but not directly because some of the adjustment is side/side, and some of it is up/down. Hopefully that confused you.

You have illustrated this well Ledzep. With a 1" horizontal offset between bore axis and sight line, but a scope that is horizontal to the ground and a 100 yard zero, you should expect that your aim point to be off at 1000 yards 10" in the opposite direction as the original horizontal offset was. This can easily be solved using the similar triangles equations from 10th grade geometry. It is not hard to see that, since the average person leveling their optic freehand so that it feels level to them will not have a horizontal axis displacement of even near 1", the concern for long range shooting of the optic being on a slightly different horizontal plane is quite minimal. Whatever slight error, I expect on the order of perhaps 1" at 1000 yards from a .1" initial offset will be wholly obscured for the shooter by errors in wind estimation, and accuracy limitations of the firearm and ammunition.

 

[Ledzep]

Yeah, it says " <1" ", less than 1 inch.

Another sweet trick to minimize it is to have your 100yd elevation zero with the windage purposely zeroed at a longer distance than the elevation so that your line of sight and trajectory converge further out than your actual elevation zero.

Using the extreme example of 1 inch, if my windage is zeroed at 300yd, and my elevation at 100yd. 100yd, 2/3" right of aim, 200yd, 1/3" right of aim, 300yd zeroed, 400yd, 1/3" left of aim..... 1000yd, 2.33" left of aim. Much better than 9 or 10 inches. Worst spot is up close (when targets are relatively bigger anyways, and still only .67 MOA off).

This fix is a sort of set-it-and-forget-it thing, too. Something you worry about once when you zero the rifle, and honestly can just about be ignored afterwards.

Long story short, you can cut out all of the above BS by mounting your scope directly over the bore, but if for whatever reason you decide it's better not to, it's no big deal, as long as the scope is level.

 

[raider1v1]

i tried the method of leveling the rifle and then looking at some weighted string, but that was getting to be too much trouble. I went and bought some feeler gauges and was done in 30 seconds. i highly recommend these. it seems to be the best and cheapest method to get the scope level w/ the rifle.