Annoying Scope Cant "Corrected" finally

[mikecr]

I like to shoot groups that are as small as I can make them, so I do bother myself about shot to shot consistency of rifles' cant. or lack thereof.

I know how important level is. I would fully miss half the Pennsylvania groundhogs I shoot at, if not for minding level with each trigger pull.
What I've suggested is that the bubble level I mind is purely perpendicular with plumb, and not directly associated with crosshair, or gun, or target. I would shoot as well with no more than a dot for POA (level wise), but I'm sure a crosshair provides better POA, as fixed by our visual processing. My hunting shots are also off Harris swivel bipods, and not rigid rests.

I don't think a level functions with gravity, but with buoyancy. It would not be easy to plumb a rest, and/or any gun area/contact you don't actually aim with, and then set a level perpendicular with that plumb, so that a gun might actually recoil perpendicular to plumb. There would always be stacked errors there, but BR shooting allows for sighters, and half the credit in it goes to precision, with then only half to accuracy.

A good number of my shots rest on a considerably canted bipod somewhere between cow patties. The barrel is not indexed,, the action is not bedded and fixed w/resp to forearm flats,, neither is my base and rings. I did not establish level on the gun itself, with forearm flats interfacing well with an actually plumb bench top. This is fine though, as none of that would help me while shooting off a bipod. And only accuracy counts for me, no sighters.
So my level is established w/resp to scope adjustments & mounted to the scope, which I aim with. Given this, my aim is plumb regardless of all else. It's an option for hunters, who dial, and I doubt it would hurt a bit for some in BR.

 

[BoydAllen]

I know how important level is. I would fully miss half the Pennsylvania groundhogs I shoot at, if not for minding level with each trigger pull.
What I've suggested is that the bubble level I mind is purely perpendicular with plumb, and not directly associated with crosshair, or gun, or target. I would shoot as well with no more than a dot for POA (level wise), but I'm sure a crosshair provides better POA, as fixed by our visual processing. My hunting shots are also off Harris swivel bipods, and not rigid rests.

I don't think a level functions with gravity, but with buoyancy. It would not be easy to plumb a rest, and/or any gun area/contact you don't actually aim with, and then set a level perpendicular with that plumb, so that a gun might actually recoil perpendicular to plumb. There would always be stacked errors there, but BR shooting allows for sighters, and half the credit in it goes to precision, with then only half to accuracy.

A good number of my shots rest on a considerably canted bipod somewhere between cow patties. The barrel is not indexed,, the action is not bedded and fixed w/resp to forearm flats,, neither is my base and rings. I did not establish level on the gun itself, with forearm flats interfacing well with an actually plumb bench top. This is fine though, as none of that would help me while shooting off a bipod. And only accuracy counts for me, no sighters.
So my level is established w/resp to scope adjustments & mounted to the scope, which I aim with. Given this, my aim is plumb regardless of all else. It's an option for hunters, who dial, and I doubt it would hurt a bit for some in BR.

When I mount a scope, the tool that I use allows me to have the line between the center of the barrel and the center of the scope plumb. Next, with the rifle in that position, I roll the scope in its rings until the vertical cross hair is also plumb, recheck that I have not moved the rifle, and then secure the scope. My varmint shooting has not seemed to suffer from this approach (I hold off rather than use clicks.), and because of the way that I post my targets, even when I am shooting a rifle that has a rounded forearm my cross hairs are level and plumb. The main thing is that whatever we do works, not that we all have to do the same thing.

 

[hogan]

Bushnell 74-3333 solves lots of problems... Has for me, anyway...

How many ever test their base for bore concentricity? Does your base align off-center?
Do you use ring alignment spuds, like Brownells sells, to align your rings? They do work, but most Picatinny type slots won't have adjustment range if the base is way out from concentric.

Do you use only receivers with integral pic rail or other base system milled to the receiver? Eliminates lots of concern and a key variable...

Brace your rifle in some sort of padded furniture vise when you mount a scope? I own a Starrett 8" machinists level but it's too high to use w/o removing scope. There are $3 plastic string levels out there but where's the confidence in that? You can try using Machinist gage blocks on the pic rail and squaring to the scope turret underside, which is usually "flat". No real gurantee your reticle is aligned off the bottom housing though...

The ol' 74-3333 can be adapted so as not to require an insert spud in your barrel. Pretty easy to determine true horizontal by reticle alignment on the sighter's grid. Don't have to go to elaborate measures.... Shows right away if your mount or base is out of concentric alignment. The grid allows lots of diagnostic possibilities. Very versatile and valuable shooting aid.

Probably could get a large piece of graph paper and staple it to your wall using a 4' carpenters level. Used to be graphic arts stores sold draftsman supplies and had xl sized graph papers. Might even mount on a picture mat and frame the graph paper so could move it or setup where you want? Real easy just to use the barrel spud and don't tighten with a death grip from hell... Keep a log and write down your on-grid coordinates for your zero(es). Easy to tell if scope has shifted. Great tool to have if you want to swap scopes between rifles or use several loads that have different zeroes.

 

[mikecr]

Hogan, when you suggest "Pretty easy to determine true horizontal by reticle alignment on", what makes you think a reticle is square to anything?
Barrel spuds & bases & rings.. How about a bore that is not actually centered in a barrel and usually exhibiting a curve? An action, integral bases or not, bedded into a stock, lying on and shot off a rest system, sitting on a bench, erected from the ground?
I'm not sure if you're talking about cant at all, or instead about offsets in zero from optically centered.

To get an entire shooting system square to ballistically level(plumb) is a hopeless endeavor.
I'm sure none of us attain it.
Boyd said: "The main thing is that whatever we do works".
But is that really the main thing? Ever?

You bump a jukebox and it plays a good tune. Well,, that worked.
Did it?
With efforts you might learn why it played and why that tune. Possibly learn that it works sometimes, and rarely the same tune.
If you had wished to impress a girl with this trick, it was better you learned these things beforehand. After all, there are good and bad impressions.

The 'main thing' (for some) might often be about consistent setup and sighters, and nothing at all about reticle cant. I frequently read reference to 'hunting accuracy' as though it's a different kind. Well don't trust merchandising out of that, unless the trick will actually work for you.

 

[BoydAllen]

In my post I was only addressing the alignment of the scope to the rifle with regard to its rotational position.

Except for Burris rings with plastic inserts, I lap every set of rings that I install a scope into. I never use the old style rings that have a rotary dovetail in the front and windage screws in the rear. If a one piece base does not sit flat on the receiver I bed it. Every screw that goes onto a blind hole gets checked to see if it is bottoming, and modified if it is. I take exceptional care with how I mount scopes, and have gotten uniformly excellent results. This would include a number of high dollar, target grade actions, and scopes that cost over a couple of grand. No scope that I have mounted has ever shown a mark when removed from its rings. My statement about there being more than one method to achieve a good result is true. Saying that it was like bumping a juke box is a cheap shot. Many do not have the same tool that I use, but that does not mean that they can not get excellent results using a different method, THAT is what I meant, not that a haphazard approach is OK.

 

[waltk]

In my post I was only addressing the alignment of the scope to the rifle with regard to its rotational position.

Except for Burris rings with plastic inserts, I lap every set of rings that I install a scope into. I never use the old style rings that have a rotary dovetail in the front and windage screws in the rear. If a one piece base does not sit flat on the receiver I bed it. Every screw that goes onto a blind hole gets checked to see if it is bottoming, and modified if it is. I take exceptional care with how I mount scopes, and have gotten uniformly excellent results. This would include a number of high dollar, target grade actions, and scopes that cost over a couple of grand. No scope that I have mounted has ever shown a mark when removed from its rings. My statement about there being more than one method to achieve a good result is true. Saying that it was like bumping a juke box is a cheap shot. Many do not have the same tool that I use, but that does not mean that they can not get excellent results using a different method, THAT is what I meant, not that a haphazard approach is OK.

This in my very limited and unprofessional opinion is absolutely true and correct.

 

[savagedasher]

I level off the scope rings or the bases . If they aren't true why own the action .
But I have my barrels timed where any effect is only vertical . Then I have my stocked trued to the bases .
You would be shocked how many of stocks
Aren't true to the action . Larry

 

[Dgd6mm]

I just screw it all together, pull the trigger and hope for the best

 

[savagedasher]

I just screw it all together, pull the trigger and hope for the best

Right lol Larry

 

[mikecr]

On cant, stress free scope mounting may be meaningless to it.
savagedasher mentions stocks not being true to the action. This should be expected, because it would never be so unless you made it so during bedding. The rest and any flat forearm need to be level, relatively, so that we impress bags for truly consistent free recoil. This doesn't happen where we're binding a stock into bags based on a separate level.
That's why I suggest it takes more than generalized to get everything in the chain as one.

 

[Drop Port]

Boyd and Mikecr hit it on the head each explained it differently and both are correct for their purpose.

If you are dialing dope the scope tracks off mechanical adjustment.

If you level off your reticle you better check your reticle to make sure its not canted and tracks true to your mechanical adjustment (turret) otherwise set it up off level gun and turret.

Most scopes are good but you still see occasional canted reticle. In that case it doesn't matter how canted it is if you are dialing as long as the turret is straight and tracks true vertical.