Rifle Scopes Leveling a scope: Plumb line and a flashlight

[wade2big]

I've never understood all the OCD that people invest into leveling the scope to the rifle, when what matters is only how level the scope is when in the firing position.

Put a level on the scope and make sure that level is level to the scope sure, but the angle of the scope to the rifle is almost irrelevant.

If we exaggerate the scope rotation to make the point, so the scope is on a ridiculous 45 degree angle, but the scope is level when firing, the bullet will travel a parallel path to the line of sight that is about 1 inch to the side of the POI. You probably would barely even notice that... unless you are shooting F Class.

If you are off by 10 degrees, which is a lot just by eye, you wont even notice the offset.

Just eye it up to the rifle and go with it.

I agree with you. Its not important in practical application. Because the offset is very minimal.

In your exaggerated example though, it would make a large difference as the distance grows. That theoretical 1” offset at POA to POI would be at your initial zero range (100 yards). That angle continues to cary as the distance grows. None of that really matters though because like you implied the offset in reality is far less

 

[DukeGSP]

if you're using the plumb bob method outside, drop the end into a bucket of water to keep it from moving. Life hack 101

 

[Tyler Kemp]

You will definitely notice a POI shift at 1000 yards with just a few degrees of cant. Try it!

 

[Rateoftwist]

Helpful. Thank you... I ran into an issue using the wheeler level system (cheaper of the 2) on my 22 lr receiver that is round with others areas of the receiver (rails etc, also at an angle)... I am going to give this method a go. However, probably way overkill for a 22 lr given effective distance but sometimes even I can get AR like that lol.

 

[PracticalTactical]

I agree with you. Its not important in practical application. Because the offset is very minimal.

In your exaggerated example though, it would make a large difference as the distance grows. That theoretical 1” offset at POA to POI would be at your initial zero range (100 yards). That angle continues to cary as the distance grows. None of that really matters though because like you implied the offset in reality is far less

I assume with my 45 degree example you would account for that offset with the initial 100 yard zero... just make sure it hits to the side by the inch, and then that would become the constant.

G David Tubbs has been running a rifle on a canted angle for a very long time for improved ergonomics and won more stuff than most guys ever will. Keeping in mind that he's mostly an across the course guy with a shooting jacket and sling.... But the point still stands.

Trying to tune out 1 or 2 degrees is fun if you just want to tinker, but it wont change the outcome.

 

[Glassaholic]

You probably would barely even notice that... unless you are shooting F Class.

I think this is a big part of the problem. What Bench Rest and F Class has introduced to the sport has been extremes of precision, from rifle building, to bullets, to ballistics, to reloading and so much more. I'm not saying it's bad, and in fact it has been a huge benefit for our sport in general, but for most shooters the tolerances required/desired for the bench rest community are not as much a factor in the tactical long range community. It's one thing to shoot a 2" group at 1000 yards, it's quite another to shoot a 2 MOA steel target at 1000 yards. Do some of the precision elements help, certainly, but are they necessary... well that is up for debate. For example, F Classers shoot at known distances and tend to prefer SFP scopes - why deal with a FFP scope if all you're ever going to use is 40x magnification at a known distance? F Classers tend to prefer 1/8 moa clicks or .05 mil clicks for more precise control over their adjustments, but for PRS style shooting this becomes a hindrance (a lot more clicks to deal with) rather than a benefit because the quicker you can dial your solution the better and your ability to "read" wind will play a much bigger factor over your ability to dial in .05 mil increments. For those F Classers on the Hide, please know I am not trying to diminish all the effort that goes into your sport because I respect what you're capable of doing at long ranges, what I'm saying is that there is a law of diminishing returns and sometimes I see guys getting so caught up in the minutia when it is not necessary for the style of shooting that most on SH aim for.

 

[DJL2]

As much effort as people put into making sure their turret adjustments track true and as quick as they are to bitch when they don’t, it’s interesting to see folks write off inducing greater error through optics mounting and body position.

 

[OldSalty]

As much effort as people put into making sure their turret adjustments track true and as quick as they are to bitch when they don’t, it’s interesting to see folks write off inducing greater error through optics mounting and body position.

Fk it, just eyeball the scope tighten it up and start smacking that 1000 yard steel.

 

[Tyler Kemp]

I assume with my 45 degree example you would account for that offset with the initial 100 yard zero... just make sure it hits to the side by the inch, and then that would become the constant.

G David Tubbs has been running a rifle on a canted angle for a very long time for improved ergonomics and won more stuff than most guys ever will. Keeping in mind that he's mostly an across the course guy with a shooting jacket and sling.... But the point still stands.

Trying to tune out 1 or 2 degrees is fun if you just want to tinker, but it wont change the outcome.

Canted rifle is ok, canted scope isn't. I too shot highpower (and smallbore), it is exceptionally common to see a tilted rifle, but betcha those sights (or scope in open) are leveled!

 

[DDT]

My opinion: if you level the scope on tilted rifle for shooting in one position (prone), it become not in level if you have to shoot in different position (kneeling position, sitting,...), so it is not a good idea to level the scope for exactly one shooting position. Better solution is leveling the scope to the leveled rifle. Not everyone use external bubble levels on their scope tubes...

 

[PracticalTactical]

My opinion: if you level the scope on tilted rifle for shooting in one position (prone), it become not in level if you have to shoot in different position (kneeling position, sitting,...), so it is not a good idea to level the scope for exactly one shooting position. Better solution is leveling the scope to the leveled rifle. Not everyone use external bubble levels on their scope tubes...

You're just fighting to defend the status quo.

The point made by referencing Mr Tubbs is there is a proven ergonomic advantage to deliberately canting the rifle.

I do acknowledge that shooting from a bench with a fixed position bipod would not allow you to level the scope, so if you choose the explore the benefit of deliberate canting of the rifle (not the scope) then you need to ensure that canting angle is repeatable in all positions.

I've never seen a PRS style chassis that would allow the Arca rail to be canted...so that would be a limitation that stock designers of the future might take into consideration.

 

[JAS-SH]

Just found this thread. I recently watched an interview with Chris Palka and Bryan Litz from Applied Ballistics. Chris is the operations manager and is in charge of all the Lab Testing they do at AB. He said that two of the most common errors in LR shooting are 1) not testing the scope elevation and windage adjustments for repeatability and 2) not having the scope and rifle plumb to each other.

He recommends the Plumb Line method, saying that the use of bubble levels result are not as accurate for LR and ELR. Of course they both also mentioned that if your shooting will all at short ranges then it doesn't matter that much, unless you shoot in benchrest competition. Then it does.

It was a long talk with Gavin Toobe and covered a LOT of stuff. You can find it here: