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HELP: Out of Windage - Scope Base Screw Hole Alignment Check?

 
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  #8  
Old 09-22-2012, 09:03 PM
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Re: HELP: Out of Windage - Scope Base Screw Hole Alignment Check?

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Originally Posted by SidecarFlip View Post
Also keep in mind that an mis-alignment of just a few thousands of an inch will be greatly amplified and extreme distance, the longer the shot, the more agregious the alignment becomes which is why at 50 feet, I can still shoot my pistol accurately but I'd never be able to hit anything if the target was at 200 yards and the pistol was a rifle with the same alignment error.
Ironically, I have a set of Leupold bases with a significant alignment error of the double dovetail slots. Even worse, the error has the slot offest to the left in front and to the right in back which results in an additive error of my scope pointing to the left compared to the barrel. It took quite a while to figure it out, and for years I just used offsets in my Burris Signature rings to straighten it out. I've now removed those bases but you are correct in that only a small misalignment can cause significant scope alignment errors.

As he's already tried 2 different sets of bases I doubt that is his problem. I just wanted to add to your comment with my own example.
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  #9  
Old 09-23-2012, 02:28 AM
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Farmerbeau,

With such short time left, you may not be able to use the proper tools to sort this out exactly. Here's an approach that will help you identify the problem. This method is a bit crude, but is accurate enough to diagnoae a problem of this magnitude.

First, find the optical center of the scope. That is done by placing a mirror against the objective rim. I've used my wife's small make-up mirror. You will see two reticles - one is the reflected image. If it's too dark to seethe reflected image, shine a light onto the mirror next to the objective. Rotate the turrets until the two reticle images over lap. If the problem is your scope, you won't be able to do this. I'll bet you a box of ammo your scope is fine.

The base holes could be off, but more likely the problem is with the barrel. I'm guessing either the barrel is mounted crooked in the receiver, or the bore is bent, or both. You can check for a crooked barrel by placing a 24-36" metal ruler against the right side of the receiver. Measure the gap between the ruler and the barrel 18" from the receiver. Then repeat for the left side. I'm guessing that the difference between these measurements is at least 0.15".

If not, then the problem is either the base mounting holes or the bore is bent. Install the base and back out the mounting screws at least two full turns. If the holes are misaligned the base shouldn't fit properly when you press down on it with your fingers - it will rock like a table with one short leg.

If the base fits snug, install the base and tighten the base screws. Now repeat the test above using the metal ruler, only this time place the ruler against the left and right side of the base. If the barrel was centered in the first test, but not in this test, the problem is with the base holes.

If everything checks out fine so far, install the base, rings and the optically centered scope. Pull out the bolt and sight something through the bore at least 20 yds away. I would print or draw a 1" dia circle with a cross centered on it. Tape it to a wall or other suitable target stand. Precisely center this target in the bore. If the problem is a bent bore, the scope will be aiming a few inches to the aide of the cross.

The real question is how to fix a problem with your rifle in time for the hunt. I would buy a set of Burris Signature rings. The 30 mm rings come with offset inserts. You can orient them to correct for the problem with the rifle. If the misalignment problem is not too severe, Signature rings should get you zeroed. Bed the base if it doesn't fit properly. Then use a torque wrench to tighten all the screws.
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  #10  
Old 09-23-2012, 08:55 AM
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Re: HELP: Out of Windage - Scope Base Screw Hole Alignment Check?

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Originally Posted by Dr. Vette View Post
Ironically, I have a set of Leupold bases with a significant alignment error of the double dovetail slots. Even worse, the error has the slot offest to the left in front and to the right in back which results in an additive error of my scope pointing to the left compared to the barrel. It took quite a while to figure it out, and for years I just used offsets in my Burris Signature rings to straighten it out. I've now removed those bases but you are correct in that only a small misalignment can cause significant scope alignment errors.

As he's already tried 2 different sets of bases I doubt that is his problem. I just wanted to add to your comment with my own example.
In theory, the bores of the rings should be parallel to each other so if the base dovetail is cut on a diagonal to the bore and you mount the bases and rings and then use an alignment/lapping bar (like a Wheeler) or in my case a shop ground length of bar stock, the misalignment would be immediately apparent when you wiped the ring set with the bar and lapping compound.

The lapping compound would remove the oxide finish inside the rings only at one extreme end instead of across the bore face. On silver rings, I use Dykem blue or red, on black rings, the oxide coating becomes the 'bluing'....

Lapping/alignment is SOP with me before I ever set any optic in the saddles. One, I want to visually ascertain if the rings are close to alignment and two, I want maximum ring to tube contact which basically eliminates any chance of the scope moving on recoil (so long as the rings are torqued to manufacturers specification) and it eliminates any chance of ring marks on the optic or in the extreme case, crushing the aluminum scope tube, rendering the optic useless, the main reason why I stay away from sopes with ring marks of any kind.

Ring marks are caused by one thing and that is misalignment of the rings thenselves in relationship to the scope tube brought about by not carefully aligning the tube to the rings or lapping the ring bearing surface beforehand. Your alignment and final accuracy will only be as good as the preperation and execution done prior to that first shot.

Along that line, I also use the lapping bar as an alignment tool when fixing the rings to the base/rail. I clamp the rings loosely to the bar and set the rings on the base/rail and attach them loosely as well. Then I go back and progressively tighten the rings to the alignment bar and then tighten the rings to the base/rail. That aligns the rings independently and parallel to the base/rail. Of course all this is predicated on the bar being true and parallel as well.

If you shoot short distance, none of this is necessary. Long distance compounds the slightest misalignment and necessitates precision, error free mounting and of course precision, error free machining by the manufacturer as well.

No manufacturer is exempt from error, or as it's been said before, shitte happens. We just don't want to be the recipient.

I read Bruce's synopsis of how to check the alignment and while that will distill the problem, the problem remains and needs to be addressed. IMO, I don't think it's a bore or barrel issue, though it may be in as much as Savage barrels screw in and lock with a retainer nut. I still would lean toward parallel misalignment of the machined mounting holes in relationship to the centerline of the chamber, a more likely scenario, at least in my opinion from owning a machine shop and having an understanding of the different operations, how they are performed and what and when inspections take place.

Barrel fixing to receiver/chamber alignment is critical and is highly likely to be hand inspected on every firearm whereas receiver/chamber rail/base hole alignment is fixture aligned and most likely not individually inspected but rather inspected on a frequency basis.

Never having been to Savage Aems or touring their shop, I can only guess, but using common machine shop practices, I can crudely deduce their inspection regimen.

Every manufacturer has to balance the human factor against the profitability factor. Savage produces what I consider to be a quality product at a reasonable cost. To do that is a fine balance between profitability and how much each firearm is, shall we say, 'carassed' by humans.

Not to demean any manufacturer on this site like Kirby (Allen Precision) but in order for Kirby to make a profit on his offerings, he has to charge appreciably more because the human factor and that skill is put into each unit. Savage is a production facility. Mass production and one off are entirely 2 different animals.

It all distills down to what you are willing to pay and what you will tolerate as far as a less than ideal situation, and, of course, how well the manufacturer stands behind their product (in this case and mine, I expect 100%).

Thats why I said earlier that the OP should contact Savage Arms and allow Savage to decide the outcome, exactly what I'm going to do with Ruger shortly.

I could very intentionally machine a rail with the through holes offset the deviate amount and bring the rail into parallel alignment with the receiver but that isn't the solution to the issue. The solution to my issue and the OP's, lies with the OEM and how thay address it.
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  #11  
Old 09-23-2012, 01:27 PM
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Re: HELP: Out of Windage - Scope Base Screw Hole Alignment Check?

before I'd go nuts, I'd have the barrel recrowned by somebody that knows what they are doing. If the crown has a ding or even the last inch or so of rifeling is dinged you will push the bullets in one direction or another. I don't recommend lapping the last two to four inches of rifeling, but that's your call. Slugging the barrel might be a problem with a .338, but you might get by with a shaved .357 lead bullet. The results may scare you to death, but then you'll have a much better idea what's going on inside it. Recrowning at least gives you a good starting point.
gary
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  #12  
Old 09-23-2012, 02:28 PM
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Re: HELP: Out of Windage - Scope Base Screw Hole Alignment Check?

There really should be a sticky for this. Its a Savage! The actions tend to not be straight, The barrels not bored straight and the threads are not true to the bent action and/or the off center/bent bore. I've got one Savage out of a couple dozen that lines up with the scope=only one!
Bruce_ventura gave some great advise but I'll add a couple more solutuons to the problem but be warned I use to milk cows for a liveing. The Burris Z rings are great if you can find them!
My favorite and easiest fix is to put on an IOR or Sightron fixed power scope in 16-20x that has LOT of adjustment=80- 150 MOAs worth. The NF br scopes are great scopes but lack much adjustment!
Leupold makes a one piece base that has windage adjustments in the rear that can get you lined up too but you usually end up shimming the back to get the ellivation required.
A couple of my red-neck fixes infolves setting the headspace to the die wich may or may not help the scope alianment? The other quick fix is putting a piece of shim on the rear ring to push the scope into alienment but unless you lap the rings afterwards its going to bend the scope and/or put some nasty ring marks on it.
Or you could send it to Fred and have him true everything up but your going to wait a long time and have just as much into it as a custom.
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  #13  
Old 09-24-2012, 11:06 AM
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Re: HELP: Out of Windage - Scope Base Screw Hole Alignment Check?

Quote:
Originally Posted by MachV View Post
There really should be a sticky for this. Its a Savage! The actions tend to not be straight, The barrels not bored straight and the threads are not true to the bent action and/or the off center/bent bore. I've got one Savage out of a couple dozen that lines up with the scope=only one!
Bruce_ventura gave some great advise but I'll add a couple more solutuons to the problem but be warned I use to milk cows for a liveing. The Burris Z rings are great if you can find them!
My favorite and easiest fix is to put on an IOR or Sightron fixed power scope in 16-20x that has LOT of adjustment=80- 150 MOAs worth. The NF br scopes are great scopes but lack much adjustment!
Leupold makes a one piece base that has windage adjustments in the rear that can get you lined up too but you usually end up shimming the back to get the ellivation required.
A couple of my red-neck fixes infolves setting the headspace to the die wich may or may not help the scope alianment? The other quick fix is putting a piece of shim on the rear ring to push the scope into alienment but unless you lap the rings afterwards its going to bend the scope and/or put some nasty ring marks on it.
Or you could send it to Fred and have him true everything up but your going to wait a long time and have just as much into it as a custom.
obvious that you've never trued an action, because if you had you'd know that Savage actions are known to be the straitest mass production actions on the market. Typically less than .0015"
gary
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  #14  
Old 09-24-2012, 11:49 AM
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Re: HELP: Out of Windage - Scope Base Screw Hole Alignment Check?

obvious that you've never trued an action

Is it really that obvious
The action may start out life straight but getting that factory nut loose has bent as many actions then it has fixed! Maybe buying cheap actions off the net has found me more problem childs then starting off with new units?
At any rate I was not really bashing Savage as they outnumber all other actions in the safe 5 to 1. They are not however without thier little issues.
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