Rifle canting and levels

[Adikted]

I understand what your trying to say and agree. I just have a hard time trusting those levels. I have 4 small levels that came with some kits. If u put all of them on a concrete bench they are not all leveling the same. I think each time you level a scope, a tall target test is the sure sign if your off or not. So left one level on the action. Put a laser plum bob on the wall and made the cross hairs level with the action. Then put an anti cant level on the scope.

Yes tall target test will tell you if your mechanics are tracking directly above the bore, if you use a reticle for holdover then you need to use it for your tall target test also, none of this works if your rifle isn't held plumb when shooting

 

[Adikted]

This is an interesting point. I was mentored to install scopes while holding the rifle. I.e. I hold my rifle while somebody else rotates the reticle to plumb. This works really good if you shoot primarily offhand, or primarily sitting, and often there ones own anatomy induces some cant in the rifle. This is fine for shooting to intermediate (500-600yd) distances.

Truly long range shooting is a different discipline. Once vertical corrections reach several feet, well as we all know, small factors start to show up. For those who holdover, it becomes increasingly important that the reticle is plumb (through the bore). For those dialing, it becomes increasingly important that the vertical erector is parallel with the SCOPE/BORE AXIS.

Let me repeat that; if you are dialing it does not matter if your reticle is level - it's the mechanical assembly in the scope that needs to be aligned with the imaginary plane running through the center of your scope and bore.

Let's say your reticle is perfectly level as most people say (or plumb as we carpenters say). Your rifle is shot in a perfectly 'level' condition. Reticle cant will show up.

let's assume 2deg of relative difference between the reticle and the erector assembly;

For an example, we are dialing 16moa of elevation at 800yd.

16(MOA) x 8(hundred yards)= 128" of vertical 'come up'

Tan 2deg = 0.03492

128" x .03492 = 4.47"

2 degrees translates to almost 4.5" of error in this example. So, we have PERFECTLY levelled our reticle and our rifle, but have weird lateral POI shifts showing up.

This is why the 'tall target test' is so important.

I missed this post when I posted my response. But it hits on something I was alluding to which is that there's no guarantee that the reticle and the mechanics in the optic are perfect to each other.

 

[7magcreedmoor]

I missed this post when I posted my response. But it hits on something I was alluding to which is that there's no guarantee that the reticle and the mechanics in the optic are perfect to each other.

Thats one issue that can be identified in the tall target tracking test. Leveling things externally is only half the battle.

 

[Hand Skills]

I missed this post when I posted my response. But it hits on something I was alluding to which is that there's no guarantee that the reticle and the mechanics in the optic are perfect to each other.

Hahah, thanks - I wish I had said it in so few words! I feel like I used too many words, and perhaps obscured my own meaning...

The other thing that should be clearly pointed out re: Tubbs and his canted reticle is the emphasis on field positions. In an NRA 'XTC' only half of the shooting is from prone, and it's limited to 600yd (500 at times). Silhouette shares similar range limitations. Purposefully canting the scope makes sense, because of the shooting positions being used. It does not make sense when shooting at half-mile + distances.

The hilarious part is Tubbs own reticle APPEARS to be canted. It was designed this way to correct for spin drift.

... Just to further muddy the waters here.

 

[Adikted]

Hahah, thanks - I wish I had said it in so few words! I feel like I used too many words, and perhaps obscured my own meaning...

The other thing that should be clearly pointed out re: Tubbs and his canted reticle is the emphasis on field positions. In an NRA 'long range match' only half of the shooting is from prone, and it's limited to 500yd (600 at times). Purposefully canting the scope makes sense, because of the shooting positions being used. It does not make sense when shooting at half-mile + distances.

The hilarious part is Tubbs own reticle APPEARS to be canted. It was designed this way to correct for spin drift.

View attachment 86053

... Just to further muddy the waters here.

I shoot my seated stages with a canted rifle, it requires a windage adjustment of 3 minutes from my standing position zero. (requires elevation too)

I wasn't going to bring up spin drift correction...

NRA long range is 1000 yard prone

Across the course is 200, 200, 300, 600 unless it's a reduced course due to range restrictions

 

[Hand Skills]

Thanks for the clarification on NRA Long range, I edited my post to agree.

Spin drift is another subject entirely. I only bring it up because the effects are hard to differentiate from reticle/mechanical alignment issues. Only for contemplation after 'tall target test' has been verified.

 

[7magcreedmoor]

Thanks for the clarification on NRA Long range, I edited my post to agree.

Spin drift is another subject entirely. I only bring it up because the effects are hard to differentiate from reticle/mechanical alignment issues. Only for contemplation after 'tall target test' has been verified.

How bout this: I know some folks who use the tall target test to deliberately roll the scope in the rings to nullify the spin drift...

 

[Rhovee]

This is getting pretty deep.

 

[Adikted]

How bout this: I know some folks who use the tall target test to deliberately roll the scope in the rings to nullify the spin drift...

First you've got to know how much spin drift you've got...

 

[WildRose]

If the scope is not level to the rifle it will cause left/right issues when dialed for distance.

Steve

Level to how your holding the rifle. If you're off a quarter inch left or right of the bore but the reticle is level to the earth your error remains 1/4" at any distance.

More directly the reticle has to be level to the pull of gravity or as you dial up the errors increase exponentially with the distance.

 

[WildRose]

Deleted

 

[Adikted]

Deleted, if you guys shoot long range you'll figure this out if not then it doesn't matter anyway, I'm out

 

[Joefrazell]

Scope cross hairs being level are much more important then the scope being level to the action. If your scope is canted your tracking at long distance will be way off.

 

[den]

in the tall target video he suggested moving the level on the scope? rather than the scope in the rings ? to correct for the impacts being off to the left or right from the zero after dialed up, pretty sure that conflicts with the level with bore flat spots ect... theory I think?