When the forend flat of my new rifle is perfectly horizontal, my action is one degree canted. (My fault when bedding) I'm shooting 1000 yard benchrest. What's the best fix? Canting the rest seems tacky. Leave the rifle level and just level the scope? If I do that, my scope is out of alignment with the bore, is that a problem? Rebed? Out of the question. Leave rifle building to the experts? Obvious. Help.
Scope/ Rifle Cant Problem
- Thread starter JerryK
- Start date
jackie schmidt
New member
Jerry
The bore of the barrel is round. It does not know which way it is up or down. besides, one degree??. You can actually see that??
I would just place the Rifle on the bags so that the stock is level with the World,, and square the reticle.
In other words, it is no big deal........jackie
The bore of the barrel is round. It does not know which way it is up or down. besides, one degree??. You can actually see that??
I would just place the Rifle on the bags so that the stock is level with the World,, and square the reticle.
In other words, it is no big deal........jackie
S
Stan Pollak
Guest
Scope Cant
Jerry,
What jackie told is probably the way to go-no big deal-Even if the cant were severe it wouldn't put you off @100yds much more than 1/8th". At 1.2degrees, I'd venture the offset is much less than that.-Stan share your sport
Jerry,
What jackie told is probably the way to go-no big deal-Even if the cant were severe it wouldn't put you off @100yds much more than 1/8th". At 1.2degrees, I'd venture the offset is much less than that.-Stan share your sport
Boyd Allen
Active member
This is what I use to set up scopes with.
http://www.brownells.com/.aspx/pid=6097/Product/EXD_ENGINEERING_VERTICAL_RETICLE_INSTRUMENT
For the most precise result you would set your cross hair vertical using a weighted string or some other dependable reference with this tool in place, and the bubble centered. Can you really see 1.2 degrees of rest cant? I think that your measuring tool has the tail wagging the dog. IMO having the center of the scope directly above the center of the barrel is the way to go. Also, I think that the bullseye levels that I see on some rests are a mistake, for several reasons. On the other hand, shooting at a single distance, once you have your scope zeroed a little cant shouldn't make any difference, as long as it is the same for every shot.
http://www.brownells.com/.aspx/pid=6097/Product/EXD_ENGINEERING_VERTICAL_RETICLE_INSTRUMENT
For the most precise result you would set your cross hair vertical using a weighted string or some other dependable reference with this tool in place, and the bubble centered. Can you really see 1.2 degrees of rest cant? I think that your measuring tool has the tail wagging the dog. IMO having the center of the scope directly above the center of the barrel is the way to go. Also, I think that the bullseye levels that I see on some rests are a mistake, for several reasons. On the other hand, shooting at a single distance, once you have your scope zeroed a little cant shouldn't make any difference, as long as it is the same for every shot.
Bob Kingsbury
New member
Many rail guns are assembled with scopes offset to one side, It has no
affect on how the gun will perform. Some shooters have scopes positioned
far enough to one side to allow being sighted with the other eye. The
Barrel, bullet and tune won't be concerned how you aquired the target.
On another side of this, if your action was bedded straight up, what
assurance do you have that the optical center agrees with the physical
center of your scope tube.
affect on how the gun will perform. Some shooters have scopes positioned
far enough to one side to allow being sighted with the other eye. The
Barrel, bullet and tune won't be concerned how you aquired the target.
On another side of this, if your action was bedded straight up, what
assurance do you have that the optical center agrees with the physical
center of your scope tube.
B
Bill Ohio
Guest
I concur.
When you start measuring stuff, you can start to go, or maybe finish going, crazy. Weighing primers. Measuring runout and neck tension and water capacity and charges and threads per inch in your lucky shooting pants. Where does it end? More importantly, does it matter where it counts -- on the target?
On the other hand, you gotta spend your time doing something. Heck, I just spent a minute typing this! )chill
eek:
A
abintx
Guest
Jerry ...
Jerry Masker wrote an article for Precision Shooting magazine entitled "CANT AND GROUP SIZE" that is printed in their publication The Benchrest Shooting Primer and begins on page 230. It's an excellent read if you like technical explanations. According to his analysis, CANT makes both a vertical and a horizontal difference even at short distances [like when you're trying to put a bullet through the same hole], and is continually exaggerated as distance increases. The Benchrest Shooting Primer is available at 860-645-8776.
Jerry Masker wrote an article for Precision Shooting magazine entitled "CANT AND GROUP SIZE" that is printed in their publication The Benchrest Shooting Primer and begins on page 230. It's an excellent read if you like technical explanations. According to his analysis, CANT makes both a vertical and a horizontal difference even at short distances [like when you're trying to put a bullet through the same hole], and is continually exaggerated as distance increases. The Benchrest Shooting Primer is available at 860-645-8776.
R
realm-aw
Guest
range level
I have a 4' level hanging on my 100 yard range backstop. Yes, it is in peril of a bullet, but has survived 3 years of casual benchrest group shooting. It is very handy for aligning cross hairs AFTER the gun has been "leveled". By the way, how do you level a target dot reticle?
I have a 4' level hanging on my 100 yard range backstop. Yes, it is in peril of a bullet, but has survived 3 years of casual benchrest group shooting. It is very handy for aligning cross hairs AFTER the gun has been "leveled". By the way, how do you level a target dot reticle?
Hokay hokay.... this is getting confusing!
Cant absolutely DOES make a difference and the difference is HUGE. But talking to benchrest guys about it can be frustrating because generally they've never actually run it through the paces because BR rifles are set on rests which are purpose designed to minimize the problem AND because they shoot designated yardages and simply cannot ever see the effect. You could set the scope 3ft over from the bore and under/over/beside it and see NO EFFECT at a single yardage. BR guys do this all the time and then say "See! Shoots bugholes! You can put the scope ANYWHERE!!"
And you CAN....... with a 3-inch or 5-inch wide forearm. Or a rail gun!
Soooooo, if you're shooting 1000yds measured, and if your rifle platform is dead stable, YES you can just ignore it. However if your rifle has a tendency to walk the bags over then you will benefit from using a scope level. The scope level can be set to anywhere..... you can just plop the gun down in the bags and level the level into place because the level is ONLY CHECKING FOR MOVEMENT..... IF YOUR RIFLE CHANGES CANT WHILE YOU SHOOT, in other words if the cant is changing, it absolutely WILL affect your group.
But if you're shooting UN-measured distances or changing distances by dialing in with no sighters...... or hunting or shooting sniper-type courses you absolutely MUST have the scope directly over the bore and the scope leveled to this centerline. Both vertical and horizontal relationships MUST coincide. OR, you must figure for the offset. In your case the offset is less than an eighth inch, not really worth talking about, but I myself would still set it up as an OFFSET, not level the scope above the bore. I would figure the LOS to be offset from the path of the bullet and realize that coincidence can only occur at one single point at a time. Because I like my forend to set flat.
Unless you're going to shoot some practical courses. In that case I'd level the scope over the bore and let the bottom surface of the stock run out. Straighten out the scope-to-bore and let the forend run out.
You have to choose one or the other
hth
al
Cant absolutely DOES make a difference and the difference is HUGE. But talking to benchrest guys about it can be frustrating because generally they've never actually run it through the paces because BR rifles are set on rests which are purpose designed to minimize the problem AND because they shoot designated yardages and simply cannot ever see the effect. You could set the scope 3ft over from the bore and under/over/beside it and see NO EFFECT at a single yardage. BR guys do this all the time and then say "See! Shoots bugholes! You can put the scope ANYWHERE!!"
And you CAN....... with a 3-inch or 5-inch wide forearm. Or a rail gun!
Soooooo, if you're shooting 1000yds measured, and if your rifle platform is dead stable, YES you can just ignore it. However if your rifle has a tendency to walk the bags over then you will benefit from using a scope level. The scope level can be set to anywhere..... you can just plop the gun down in the bags and level the level into place because the level is ONLY CHECKING FOR MOVEMENT..... IF YOUR RIFLE CHANGES CANT WHILE YOU SHOOT, in other words if the cant is changing, it absolutely WILL affect your group.
But if you're shooting UN-measured distances or changing distances by dialing in with no sighters...... or hunting or shooting sniper-type courses you absolutely MUST have the scope directly over the bore and the scope leveled to this centerline. Both vertical and horizontal relationships MUST coincide. OR, you must figure for the offset. In your case the offset is less than an eighth inch, not really worth talking about, but I myself would still set it up as an OFFSET, not level the scope above the bore. I would figure the LOS to be offset from the path of the bullet and realize that coincidence can only occur at one single point at a time. Because I like my forend to set flat.
Unless you're going to shoot some practical courses. In that case I'd level the scope over the bore and let the bottom surface of the stock run out. Straighten out the scope-to-bore and let the forend run out.
You have to choose one or the other
hth
al
M
mks
Guest
Aside from altering the path of the bullet from the barrel to the target, cant also affects the motion of the rifle during recoil. Ideally, we would like all vibration of the barrel and the whole rifle to be in the vertical plane. If the center of mass of the stock, action and barrel, and scope are all aligned in a vertical plane, then forced vibrations are in general minimized in the horizontal plane. (Asymmetries in deformation during recoil, say from a loading port on one side of the action can also force motion in the horizontal plane. Vaughn talks about these things in his book.) Cant misaligns these masses and increases horizontal vibration, which cannot be compensated for in a group of shots with variation of barrel exit time, unlike vertical vibration which CAN compensate for different barrel exit times.
It would be preferable, then, to keep the stock and action/barrel aligned in a vertical plane, rather than leveling the action. On the other hand, the sine of 1.2 degrees is 0.021, so if the CG of the stock is say 1.5" below the bore, the cant would move its CG horizontally relative to the bore by 0.032". How much this affects accuracy can only be estimated, as far as I know. From VarmintAl's simulations, an ES of 50 fps can cause a vertical POI shift of as much as about 0.1". If the horizontal POI shift scales linearly from the vertical shift, then the estimate would be 0.0021" of horizontal dispersion induced by the cant.
Probably not enough to worry about, especially considering that most rifles are not balanced in transverse plane in the first place. Depending on the direction of cant, it may have made the balance better.
SWAG's (Scientific Wild A$$ Guesses) by,
Keith
C
Cheechako
Guest
What Al said (we agree). It does make a difference at 1000 yards. Short of rebedding, make sure the reticle is aligned with the action and make adjustments in your front rest to bring the whole thing to level. I don't think that a foreend 1 1/2 degrees off level, and anything it may do to the tracking, will amount to a hill of beans compared with trying to read the conditions at 1000 yards.
JMHO
Ray
JMHO
Ray
jackie schmidt
New member
Cant......Can't
If you set the Rifle in the bags where the Stock is level, and then set the crosshairs so that they are plumb, that is all that counts. It's the Reticle that you have to keep plumb with the world shot after shot to maintain the exact referrence.
You could even set the entire Rifle in the bags with some cant, loosen the scope rings, and turn the scope to where the crosshairs are dead plumb with the World, as long as you keep the crosshairs plumb, shot after shot, that is what counts.
All of those articles that every body is referring to has to do with a shooter not getting the crosshairs dead plumb after every shot, not the actual assembly of the action in the stock.
It makes no difference if the action is exactly to the Nth degree in the stock. Sure, for athsetics, it is desireable, but 1.5 degrees. Come on........jackie
If you set the Rifle in the bags where the Stock is level, and then set the crosshairs so that they are plumb, that is all that counts. It's the Reticle that you have to keep plumb with the world shot after shot to maintain the exact referrence.
You could even set the entire Rifle in the bags with some cant, loosen the scope rings, and turn the scope to where the crosshairs are dead plumb with the World, as long as you keep the crosshairs plumb, shot after shot, that is what counts.
All of those articles that every body is referring to has to do with a shooter not getting the crosshairs dead plumb after every shot, not the actual assembly of the action in the stock.
It makes no difference if the action is exactly to the Nth degree in the stock. Sure, for athsetics, it is desireable, but 1.5 degrees. Come on........jackie
Not really.
Let's exaggerate the offset a little....
The scope is 1.5 inches above the bore and DEAD LEVEL but it's offset 3' to the side.
It's obvious (diagram it on paper, top view) that the LOS and the bullet will CRISSCROSS only at one point when you're sighted in. (discounting spin drift and wind...)
This is exactly why IF I have any offset I always work with parallel offset rather than bringing the two lines together. I'd rather figure that the bullet and the LOS are running parallel but an eighth inch off than do the whole convergence thing. Beyond 350yds there's enough other junk to worry about, the bullet is starting to drift, it's parabolic trajectory is starting to corkscrew..... you got ENOUGH to worry about without adding in crossover!
al
A
amamnn
Guest
Why was this Q not posted on the 600/1000 yard section where it would have some relevance? Why did the moderator not suggest that?
Bob Kingsbury
New member
The question is quite relevant to any shooting disipline. How the gun is
supported and with what repeatability is really the issue. Short range BR
with flat bottom stocks are not imune to cant.
supported and with what repeatability is really the issue. Short range BR
with flat bottom stocks are not imune to cant.
G
gt40
Guest
This is how I level my vertical cross hair. I like the B-Square level that attaches to my Picatinny rail. I am a little lucky because from my deck I have a clear view of the corner of my neighbors house. I put a long carpenters level against the house and found that it is perfectly vertical. It is about 100 yards from my deck where I put my rifle on a table with the B-square leveled with the rifle. Then while looking through the scope in the loose rings turn it until the vertical cross hair is right on the edge of the house. Then I tighten the rings and turn the up & down turret all the way up and down and if it stays right on the edge it is perfect. Sometimes when tightening the scope rings it will twist the scope so be careful alternating when tightening the screws.
Here is a picture of a B-square level on my rifle.
gt-40
Here is a picture of a B-square level on my rifle.
gt-40
Attachments
Last edited by a moderator:
This would be a vote from the "get the metal right and let the stock run wild" side of the room.
Good solid method though.
al
O
Old Gunner
Guest
Just trim the bottom of the fore end. If the design allows for it that is.
Unless the inletting was loose as a goose before you bedded it the action should have settled in as close to where it should be as you'll ever get it.
Unless the inletting was loose as a goose before you bedded it the action should have settled in as close to where it should be as you'll ever get it.