Crossbow Nation banner

1 - 17 of 17 Posts

·
Registered
Joined
·
59 Posts
Discussion Starter #1
Ok so with both eyes open I thought I had it perfect. Them I closed one eye and it was off. Should I turn scope till it's centered in the picatinny rail or with the limbs? Both are diff.
 

·
Premium Member
Joined
·
1,260 Posts
I use two levels at a time but one works just as well if you can secure the xbow once levelled.

I put one level on the shooting rail to level the xbow.
Then I put a level on top of the elevation turret to level the scope crosshairs.

To really dial the crosshairs in, hang a 4- 6 foot long plumb bob some 5 to 10 yards out in front of your target bag and align the vertical crosshair with it.
Then torque the scope screws to proper settings.

By design, the limbs, picatinny and shooting rail should all be level.
Which xbow and scope are you referring to?
 

·
Registered
Joined
·
78 Posts
I have a good eye for things being out of level or plumb. A picture that is off just a bit sticks out like a sore thumb so I do mine by eye sight only. Both eyes open, dominate eye looking through the scope. Hold the bow with limbs level then close that eye and the horizontal line will tell me if it is level with the bow. Chances are your not going to hold the bow perfectly level when your ready to shoot at game so unless your taking 40+yd shot it won't make much difference if it's not in perfect alignment. Just my opinion on the subject.
 

·
Registered
Joined
·
828 Posts
Canting a crossbow will create a POA vs POI problem. Getting the xbow level and the scope cross hairs plumb/level is an important first step.
Next step is understanding the effects of bow canting. Hunting situations at some point will not allow perfect level conditions. The Indian must practice, practice and practice some more to understand what canting will do to his POI vs POA.
 

·
Registered
Joined
·
108 Posts
Dynamo nailed it. I use pretty much the same system for my crossbows and rifles. The levels have no judgement and just report the facts. Almost all top scope turrets and rails are flat, so it isn’t all that hard to align them; and it’s very important that we do - canting the scope will affect POI at longer distances. An significantly misaligned scope is obvious at first glance - if it isn’t aiming correctly, bolts won’t impact correctly.

Biggest mistake I see most folks make here is once they level the scope to the barrel they just crank down the scope rings without checking to ensure they are maintaining their level. I painstakingly do a uniform, balanced tightening, checking the levels throughout the process.

Good luck
 

·
Registered
Joined
·
59 Posts
Discussion Starter #7
I use two levels at a time but one works just as well if you can secure the xbow once levelled.

I put one level on the shooting rail to level the xbow.
Then I put a level on top of the elevation turret to level the scope crosshairs.

To really dial the crosshairs in, hang a 4- 6 foot long plumb bob some 5 to 10 yards out in front of your target bag and align the vertical crosshair with it.
Then torque the scope screws to proper settings.

By design, the limbs, picatinny and shooting rail should all be level.

Which xbow and scope are you referring to?
Hawke XB30 pro
Scorpyd 420.
Thx
 

·
Premium Member
Joined
·
1,260 Posts
Canting a crossbow will create a POA vs POI problem. Getting the xbow level and the scope cross hairs plumb/level is an important first step.
Next step is understanding the effects of bow canting. Hunting situations at some point will not allow perfect level conditions. The Indian must practice, practice and practice some more to understand what canting will do to his POI vs POA.
Yes, canting (or tilting) the xbow will also cause a fade right or draw left depending on the arrow fletching, the amount of wind and a host of other things that I am no expert in LOL.

I believe that most arrows are fletched with a right hand twist in the vanes so will spin clockwise toward the target.
This spin can make the arrow dip down and to the right very slightly, depending on distance.
Same as a bullet leaving a rifled barrel.
A left hand twist in the vanes will do the opposite, i.e. spin CCW and dip down and to the left.

The main point being, there are so many variables that will cause stray or inconsistent shots, so we should do our best to eliminate as many as possible, like properly aligning the scope, before we even shoot.
 

·
Registered
Joined
·
78 Posts
Bohning, in all the testing they have done recommends a straight vane for crossbows due to the speed. This would remove two of the variables. Most of my shooting is less than 40 yds so a slight cant to either side would probably have less impact on the POI than my being able to hold rock solid. Age has a way of changing that ability.
 

·
Registered
Joined
·
1,852 Posts
I use 2 levels. Put one the riser surface that is machined parallel to the limbs.
Put the 2nd level on the rail. Align the riser to the rail.
Some scopes crosshairs aren't perpendicular with the top turret. So use a plumb bob positioned at a distance in front of the crossbow to align crosshairs with while using a level to level crossbow.
A building wall can be used for plumb bob.
Next mount a bubble level on your riser so when you practice you minimize canting.
 

·
Registered
Joined
·
59 Posts
Discussion Starter #11
Yes, canting (or tilting) the xbow will also cause a fade right or draw left depending on the arrow fletching, the amount of wind and a host of other things that I am no expert in LOL.

I believe that most arrows are fletched with a right hand twist in the vanes so will spin clockwise toward the target.
This spin can make the arrow dip down and to the right very slightly, depending on distance.
Same as a bullet leaving a rifled barrel.
A left hand twist in the vanes will do the opposite, i.e. spin CCW and dip down and to the left.

The main point being, there are so many variables that will cause stray or inconsistent shots, so we should do our best to eliminate as many as possible, like properly aligning the scope, before we even shoot.
I have a good eye for things being out of level or plumb. A picture that is off just a bit sticks out like a sore thumb so I do mine by eye sight only. Both eyes open, dominate eye looking through the scope. Hold the bow with limbs level then close that eye and the horizontal line will tell me if it is level with the bow. Chances are your not going to hold the bow perfectly level when your ready to shoot at game so unless your taking 40+yd shot it won't make much difference if it's not in perfect alignment. Just my opinion on the subject.
That's what I did. I just made it so I'm happy with it. I'll see how it shoots later. I like to keep it basic.
 

·
Premium Member
Joined
·
1,260 Posts
Bohning, in all the testing they have done recommends a straight vane for crossbows due to the speed. This would remove two of the variables. Most of my shooting is less than 40 yds so a slight cant to either side would probably have less impact on the POI than my being able to hold rock solid. Age has a way of changing that ability.
Wow, that is surprising coming from Bohniing but I am no expert.
Their recommendation goes against aerodynamics principals for projectiles.

Straight vanes, without a helical twist, are up for debate.
Most recommend a twist in the vane if applying them straight.

Straight vanes allow the arrow to be affected more by the air around it, similar to throwing a "knuckleball" in baseball.
Spinning the arrow when it is moving gives it a gyroscopic effect to stabilize and increase the ability to cut through the air straighter.

Again, I am no expert and am merely repeating what I have learned.
 

·
Registered
Joined
·
10 Posts
You can use a feeler gauge between the rail and the flat part on the bottom of the scope as well. A deck of cards will also work in a pinch.
 

·
Registered
Joined
·
78 Posts
What I got from Bohning was with information I got when I purchased their 3 vane jig several years ago. It is possible that things have changed since then. I have fletched mine with the straight clamps and they shoot straight out to 30 yds. 2" group is as good as I can hold even off a rest but I am not 50 any more either.
 

·
Registered
Joined
·
1,823 Posts
Bohning, in all the testing they have done recommends a straight vane for crossbows due to the speed. This would remove two of the variables. Most of my shooting is less than 40 yds so a slight cant to either side would probably have less impact on the POI than my being able to hold rock solid. Age has a way of changing that ability.
I have only used straight vanes or slight offset in all my crossbow arrows. Can't see how anything more angled would work.
 

·
Premium Member
Joined
·
1,260 Posts
What I got from Bohning was with information I got when I purchased their 3 vane jig several years ago. It is possible that things have changed since then. I have fletched mine with the straight clamps and they shoot straight out to 30 yds. 2" group is as good as I can hold even off a rest but I am not 50 any more either.
OK, that is the thing right there.
It all comes down to "what is good enough and works for you".

You are shooting 30 yards with 2" groups.
We are shooting 77+ yards and are striving for same hole accuracy.

Some more examples of how imparting a spin increases distance and accuracy:
When muskets were invented, they were accurate to 50 yards or so.
When rifling was added to the inside of the barrel, the accuracy tripled to 150 yards.
That was with using a round, lead ball.

Changing to modern bullet-like projectile shapes increased the accuracy and distance tremendously.
Similar to a quarterback throwing an NFL football, the tighter the spin he applies when throwing the ball, the farther and more accurate his throws are.

Vane lengths also help to steer the arrows.
It is believed by many that 2" long vanes are OK for shorter distances.
When shooting 50+ yards, it is recommended to use 3 to even 4" long vanes for more stability.

We are testing and learning something everyday.
We accept what those with decades of experience have tested before us and trust that it is correct, unless we find something better that works for us in our shooting environment.
But the main thing is that you enjoy what you do and have fun doing it safely.
:)
 
  • Like
Reactions: KTownKiller

·
Registered
Joined
·
78 Posts
I have been shooting Incidious arrows by Ten Point. Got a dozen new with the bow several years ago. I have 8 Eagle Claw arrows with 3" Bohning vanes on order. Never thought about vane angle and the listing does not mention it either. Wyavern Creations is building them and I trust his judgement as he knows a whole lot more than I ever will. Will find out then they get here I guess. Not going to ask as they are in peek season and don't need to be bothered with trivial stuff from me.
 
1 - 17 of 17 Posts
Top