Why don't scopes & rings come with witness marks???


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AKElroy
September 1, 2009, 12:50 PM
I have mounted a number of scopes over the years, and it is always frustrating to true the plane of the reticle to the bore centerline. Why don't rings & scopes come with witness marks to make it easier to mount keeping the reticle level??

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ants
September 1, 2009, 12:53 PM
Probably because mounting holes, mounts and rails aren't cut true, either.

And the real proof is in the shooting.

AKElroy
September 1, 2009, 12:58 PM
Agreed, but having a single line running the length of the scope on the same plane as the verticle crosshair would definately help to get it close. I mounted a scope last night, eye-balled as best I could.

I tested it today on a level purch, pointing at a known level referrence, and found it way off. Frustrating. I would have done this last night, but my horizontal referrence was in the dark.

highorder
September 1, 2009, 01:03 PM
Some, perhaps many people cant the rifle slightly when they actually shoot.

The crosshairs should be level when the rifle is held in the shooting position, as opposed to actually being true to the rifle.

imo, I think the scope should be mounted true, and the rifle held level, but thats not always the case.

usmc1371
September 1, 2009, 04:28 PM
I have to agree with you it would make it alot easier to get it close, better than the eye ball method.

627PCFan
September 1, 2009, 04:30 PM
+1 for highorder. Im right and cant to the right naturally with my Tikka which is how I have it set. If you bench the gun the top of the reticle is slightly to the left-

Temp430
September 1, 2009, 04:51 PM
I glanced over a the following short article on scope cant error:

http://www.microlevel.biz/cant_errors.html

What I took away from it is that a 5 degree cant in a scope's cross hair amounts to a 3.75 inch error at 500 yards.

Most people can easily eyeball a scope's vertical cross hair to be within less than 5 degrees of true vertical. So unless you shoot at ranges > 500 yards, don't worry about it.

SeekHer
September 1, 2009, 05:29 PM
Don't line up to the horizontal but the vertical, much easier to do...the corner of any building works fine...

rcmodel
September 1, 2009, 05:33 PM
A pair of $1.99 bubble line-levels from the hardware store work in the basement.

Put one on the rifle receiver or magazine bottom and level it.
Then put the other one on the top of the scope turret or cap and level it.
Tighten the screws.

Voilą!
The scope and rifle are on the level!

rc

AKElroy
September 1, 2009, 08:43 PM
Put one on the rifle receiver or magazine bottom and level it.
Then put the other one on the top of the scope turret or cap and level it.
Tighten the screws.

The scope I mounted yesterday is an old K-4; the turret is domed as is the adjustment knob. To make it worse, the rifle is a 94 AE; with the reciever, well, angled. I was able to purch the rifle on a half wall & get it lined up with the window blinds. Close enough for a .30-30---

matrem
September 1, 2009, 09:03 PM
What I took away from it is that a 5 degree cant in a scope's cross hair amounts to a 3.75 inch error at 500 yards.
Not ideal,but unless you change the turrets & as long as you hold the same cant, it means nothing at any distance.

Ratshooter
September 1, 2009, 09:06 PM
Mount your rifle in a gun vise and use a square to sure the screws in the buttplate are vertical. Make sure whatever your gun vise is sitting on is level. Hopefully you have your rifle pointed at the corner of a neighbors house or some other vertical object.

If nothing else tack a small peice of rope on the wall with a weight on it. Line the vertical crosshair up with that. You don't have to use a gun vise either. I you my front rest and sand bags on the kitchen counter top.

Also getting your scope square with your rifle will help correct the canting you are doing with your rifle.

jim in Anchorage
September 1, 2009, 09:15 PM
OK, I may be thinking wrong here, but if you are holding at the intersection of the cross hairs[like a dot, really] what does it matter what the horizontal/vertical lines are doing?

matrem
September 1, 2009, 09:19 PM
I will retract part of my post # 11. Gravity does pull straight down.
Needed to edit for those who "holdover".

Uncle Mike
September 2, 2009, 12:29 AM
OK, I may be thinking wrong here, but if you are holding at the intersection of the cross hairs[like a dot, really] what does it matter what the horizontal/vertical lines are doing

It doesn't...UNLESS you adjust your crosshairs. Then as you raise the intersection of the crosshairs, the POI will also walk off left or right in addition to raising.

If you get some machinist parallels and put them inside the receiver on your bolt rails(bolt action rifle), you then build them up till the flat bottom of the scope is setting on them.

Most scopes have a flat, and square to the reticle, bottom on them at the turret.

Most firearms have a flat, and square to the bore place machined somewhere on or in the receiver you can access.

Runningman
September 2, 2009, 12:41 AM
Why don't rings & scopes come with witness marks to make it easier to mount keeping the reticle level?? Because reticles can be canted within the scope tube.

Bought a Reticle Leveler more than 15 years ago. I see they are discontinued now but this will give you an idea how they work. http://www.midwayusa.com/viewProduct/?productNumber=360476

Not ideal,but unless you change the turrets & as long as you hold the same cant, it means nothing at any distance. But what if you shoot off a benchrest at 100, 200, 300, and 600 yards. Typically you are going to be moving turrets and it is frustrating enough sometimes dealing with wind conditions without adding in another factor.

Runningman
September 2, 2009, 12:44 AM
http://www.6mmbr.citymaker.com/i/Reader%20Photos/Leupold_Canted_6-20LRTweb.jpgFor example look at the canted reticle in this picture.

Maverick223
September 2, 2009, 01:06 AM
From my experience the most accurate way to plumb a scope is to use a good carpenters level across the action and then use a plumb-bob at distance to get everything true. An alternative method is to use a bubble level attached to the action and the aforementioned plumb-bob. The level will also aid in shooting at distance. :)

usmc1371
September 2, 2009, 02:41 PM
"What I took away from it is that a 5 degree cant in a scope's cross hair amounts to a 3.75 inch error at 500 yards."

Show me a HUNTER with a HUNING Rifle who can hold 3.75" at 500yds under HUNTING conditions and I will be really impressed. I don't think I have to worry about that with my ruger all weather 300wm and factory loads. Maybe off a good bench, under ideal conditions, I could tell my sub 1/2 moa accurate Les Baer .204 was off 3.75" at 500 yds but i doubt it.

Pulsar
September 2, 2009, 03:19 PM
Show me a HUNTER with a HUNING Rifle who can hold 3.75" at 500yds under HUNTING conditions and I will be really impressed. I don't think I have to worry about that with my ruger all weather 300wm and factory loads. Maybe off a good bench, under ideal conditions, I could tell my sub 1/2 moa accurate Les Baer .204 was off 3.75" at 500 yds but i doubt it.

If Im hunting and I see a deer at 500yds and Im taking the shot. I will have more that enough time to set up for a rock solid shot.

highorder
September 2, 2009, 03:38 PM
If Im hunting and I see a deer at 500yds and Im taking the shot.

Wow, I'll pass on that shot.

I'm either less confident, or more honest.

Dr. Tad Hussein Winslow
September 2, 2009, 03:41 PM
A. It's an excellent question and should be done. It's a lot easier/cheaper/faster/more convenient than a separate bubble or other leveler with or without plumb bob, or eyeballing it.

B. Yes, it can and does matter what the hairs are doing, even if the center is always on the target, if your hold is at all different each time. The bullet goes up and then back down - not left and right. Think of this way. If you turn the gun 90 degrees to the left and shoot and have the center of the crosshairs on the target, do you think it will hit the bullseye? No, it won't - not even close - because now the bullet is going LEFT (the "old up") instead of up, and just keeps going further and further left as there's no counteracting force against it as gravity would be against an up vector. If you're canted left 5 degrees, smaller error (5/90ths of the full 90 degree error), but still an error.

C. No it doesn't matter for most any hunting scenario to be off by up to 10% or so toward 90 degrees, but it can't HELP either, and some of us are OCD about our guns. And it DOES matter for long range practical/target shooting.

I'm either less confident, or more honest.

You're probably more honest, and/or have less 'false and imprudent confidence'.

Clark
September 2, 2009, 05:58 PM
Barrel break in for a bull barrel and Leupold scope.

You don't want a cow barrel:
http://www.youtube.com/watch?v=TRRahHX9Zkg

Pulsar
September 3, 2009, 12:58 PM
this is a hijack
but i wrote that about someone hunting and not have a good shot to have the 3 inch make a difference

rockstar.esq
September 3, 2009, 09:50 PM
I think it's a good idea, even if the "Huntin-accuracy" folks dismiss it there's the simplicity of being able to dismount and re-mount your optics with some repeatability due to the witness marks. Personally I'm still somewhat annoyed that it's standard practice for every maker to do their own thing. Ambiguous names like "high, medium, and low" don't tell you squat about how close the objective will be to the barrel. It's almost funny that there are literally thousands of different cartridges and they each have a distinctive name, yet every scope ring maker seems to believe their version of "low" is the right one. For the record I think the idea should be expanded to have witness marks and tension indicators on all scope hardware. All rings should be named by their actual measurements. All scopes should be labeled with their minimum scope ring & mount height.

Probably the most pitiful part of all of this is that scopes were created to help the shooter get all the accuracy they can out of the rifle yet the mounting hardware is hopelessly disorganized and totally lacking in meaningful datum points.

Maverick223
September 3, 2009, 09:53 PM
I agree...but good luck in convincing them to do it...optics doesn't have a SAAMI spec. and you're not likely to be injured or killed if the scope is too high or low. :)

jim147
September 4, 2009, 01:00 AM
While I understand the OP's point, the tolerance stack could be huge. So there is no profit in it to add a witness mark.
The receiver is drilled at the factory, the bases being brand A are made in China. The rings being brand B are made in Korea, and the scope is made in Japan.

Now the receiver is drilled slightly off, one of the bases in tightened down to the point of smashing it slightly and the rings were never really meant to fit those bases. Now the scope is being blamed for being off because the witness marks don't line up right.

Set it up the way you want it. Then learn to shoot it that way out to any distance you feel you may need to shoot.

IIRC, Tubbs cants his scopes because that is the way he shoots. I don't think I can outshoot him. I have three rifle that make tiny groups. I have only put a level on one of them.

jim

Uncle Mike
September 4, 2009, 02:05 AM
The effects of canting is simply because of design form.

A bullet or a barrel does not know which way is up or down, or at what point it is oriented to... If you could fire a bullet from a barrel that was just 'sitting' there, in space, and this barrel had no receiver, bolt or stock, and there was no outside force acting upon it...

That barrel could be rotated around the bore center line axis, stopped at 'any' point around this axis and fired... the bullet will act the same, no matter at what point around the bore center line axis the barrel was fired.

Only the center of gravity offset(arm) at certain points(stations), the holding of the firearm by the shooter and the acting forces of recoil(force vector) will cause the act of 'canting' to have an effect on the bullet.

chevyforlife21
September 4, 2009, 02:09 AM
good point this problem has made me take a scope off one of my guns and not even use it cuse it frusrates me too

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