longrange shooting and rifle comfort

[Tac]

I have recently purchased a scope level and set it up per reccomended specs hung a piece of string with a weight and set level to crosshair being inline with the string. When i go and shoot my rifle i now find that i have to torque the rifle to get the level to center and the butt is not comfortable in the pocket of my shoulder. I would like to rotate the scope in the rings to get buttstock in my shoulder and be comfortable. Will this effect accuracy more or is being comfortable more important? I seem to shoot it well out to 700 yards without paying attention to canting but if i have to torque the rifle it seems accuracy would suffer.

[briant_az]

Did you level the gun before you leveled the scope?

[lancetkenyon]

Level gun, level scope reticle (make sure reticle is level inside scope tube). Canting your rifle will cause shift in POI at distance. Depending on how much cant, and how far you shoot, it can be negligible or enough to cause a miss.

 

 

[Tac]

not canting the scope I'm wanting to cant the gun and level the scope. how will that effect overall performance?i understand if you hold the crosshairs canted in the scope but what if the scope is straight and the rifle is canted. so basically moving the scope to the side but keeping it vertical

[lancetkenyon]

Depends a bit on the runout and timing of your barrel. If it is a factory barrel and rifle, I doubt it was timed at 12:00 or 6:00, so might not make a difference. If you cant your rifle just a bit to get comfortable, and level your reticle, and ensure proper POI when you sight in at 100 (or 200) yards, it might not make much of a difference. Biggest thing is make sure your rifle hits where you want when you set it up, and make sure you keep your reticle level when shooting in the field. Repeatability is more important than a perfectly set up rifle.

[rcdinaz]

Lance I know you know this but it will still be the same as your original statement. The scope offset is what is canting off of the axis so a canted rifle and a plumb scope is the same issue. Maybe the degree varies a bit, guess this is what you are saying.

 

I am not trying to be a stickler, just that your original post was a great example and OP should know it still applies. Correct me if I missed something.

 

Never have thought about barrel timing, may have to do some reading on that one. I don't shoot any bench comp but it may be something they take notice of.

[308Nut]

I've researched this to death and analyzed the equations from every angle (no pun intended). The bottom line is that having a slightly canted rifle with the scope level is no problem AS LONG as your scope is level for all shots which it should be for rifles that are level with their scopes too. Once you're sighted in, you're good to go. The pictures in a previous post do a good job of illustrating what happens when you're canting a rifle but that's based on canting a rifle AND scope together.

 

Being comfortable is important.

[lancetkenyon]

As for "timing" a barrel, we all should know that a bore is NEVER a truly straight path. It can vary as little as .0001" to as much as .0050" or more and still shoot very sub-moa. If you "time" a barrel, or make sure the bend in the bore is at 12:00 or 6:00, you SHOULD have a more predictable bullet flight path. I sincerely doubt ANY factory barrel has ever been timed. A good gunsmith should check this on a custom barrel, and ensure your barrel is timed to give you the best opportunity of true centered bullet path from the rifle.

 

I think a few degrees (less than 3°) of rifle cant with the reticle leveled would not make a huge difference, but there are definitely ways to get around it, and as long as you know your actual drops and offset, you can account for them when shooting longer distances. But you have to go out and physically shoot at these distances to confirm what your rifle ill be doing.

 

I can 100% say for certain that canting a rifle 3° that was set up for 0° cant WILL make a huge difference at 800 yards. Even at 500 yards.

[Becker]

As mentioned above I don't think rifle cant changes anything. Just scope cant. You essentially can shoot a gun upside down. It all comes down to the path of the bullet in flight. Basically we all account for the bullet going straight up and down as it moves down range (as the diagram above shows before canting the gun AND scope). You can achieve that like I said "upside down" if you like. Think of your vertical post in the scope as the up wards movement of the bullet until it reaches the highest point in its trajectory. Any ways doesn't matter how you hold the gun as long as your scope is level!

[lancetkenyon]

Has anyone ever tried the sideways drill with their rifle? Lay your rifle 90° flat, and if you know the corrections to make on your scope, you will hit what you are aiming at. But you have to make corrections. And I doubt you can hold a rifle upside down as long as the reticle is level and still hit your POA unless you are at very close range.

 

Look at a lot of the military teams designated marksman rifles. They are equipped with a scope, and offset open sights on a 45°for CQB scenarios. For closer ranges, they are plenty good enough. For the longer shots, they go to the scope. Once a sight is dialed in for a specific distance, your rifle will hit if you have it set up for that. Alter anything, and your POI will shift.

 

Set a rifle up on a cant, with the reticle level and verified POI at 100 yards, and it will hit at 100 yards. Change anything, and POI will change. I still think it will deviate at distance a bit.

 

It would be interesting, AFTER HUNTING SEASON, to see if it truly does deviate from POA at distance. Not just doing the math, or reading articles, or researching, but going out and actually testing.

[kwp]

This is really a simple trigonometry problem. Assuming no wind and no spin drift, the ballistics come out of the equation.

If the rifle is canted but scope is plum, the result is that the vertical axis of the bore is slightly left or right of the vertical axis of the scope.

Let's say you have a scope height of 2" and rifle cant of 3 deg. Trig calcs the bore axis being 0.105" off the scope axis.

Now let's say you sight in at 200 yards. To do so you would have to adjust the reticle to account for this slight offset. With a 200 yard zero, the look angle would be 0.000836 deg off the flight of the bullet (trig again).

If you project this look angle out to 1000 yards the POI would be 0.4" off of center. (Smaller than a scope can adjust for and not even noticeable when compared to group sizes at that range).

Obviously a greater cant will magnify this number.

 

The takeaway here, get your rifle as close to plum as you can and then mount your scope plum and you'll be good to go.

[Tac]

Less than 1/2 inch off center is negligible at 1000 seems like way more human error involved make it comfy and scope plum shoot it and see what happens

[rcdinaz]

I was searching and I found a picture I remember seeing on another site take a look. Anyway Tubb's has a bunch of stuff on the topic and has rifles with some extreme cant and scope height as an example. Apparently demonstrating the trig KWP posted. My bad, I guess it really doesn't matter as long as the scope is level when shooting. Of course Tubb's sells his own version of an anti cant level that attaches to your scope.

[10Turkeys]

rcdinaz, That picture is a chin stock. Delevoped for Rifle Silhouette by David Tubb. Caused quite a clammer back in the day, quite a few people purchased the stock and then the NRA made them illegal to use. David used the same set up when he was shooting the Sportsmans Team Challenge when it was popular. Tubb was a Great shot and innovator.

[lancetkenyon]

Good example of two sights. Scope is leveled with a level rifle, not to be used with a canted rifle. Red dot is used for close shots.

 

 

Here is about as honest of a test as you could get. Frank Galli is world renowned.

 

http://www.scout.com/military/snipers-hide/story/1540059-canted-rifle-level-scope