S.O.S.-New Scope setup looks 'left'...a lot!

[sdowney]

I'm getting ready to sight in my new scope and notice the scope crosshairs are looking way to the left of the bore. I'm talking on the order of 2 inches left at 30 yards or so. Even with full windage dialed in, I still can't quite get the vertical crosshairs to line up with the bore.

I took the scope off and played with all the screws, trying them back on a dozen times. Nothing. Then, I switched rings fore and aft, same result (tells me it's not the rings or it would lean right after the swap).

All the parts are new except the rifle. The rifle used to have standard Leupold rings with a Vari X III. Now it has an EGW picatinny 20 MOA base, Seekins 1" rings, and a Zeiss Conquest 6.5 x 20 x 50mm. Apparently, the problems lies either in the a) holes tapped into the receiver or b) the EGW base is off.

Any ideas/fixes from the gurus??? I hate to start buying bases till I find one, but I really hate to have a receiver who's holes are wrong.

Many thanks in advance, guys.

Scott

 

[Topshot]

Two inches at 30 yards is not that far off. It is only just over 6 MOA at 100 yards. You should be able to get your windage accross that far. After all you have a 20 MOA rail fitted and you should be able to still center the cross hairs in the vertical with that. Have you tried the original scope on the new base?

Try spinning the base about 180 degrees, as you did with the rings. It will be pointing up instead of down but it may give you an idea of what's going on.

If the old bases aligned the old scope OK then the screw holes are most likley OK.

I would center the windage turret in the middle of its travel then fire a shot at a target to see where the actual point of impact lies. This will give you some true data to work from.

If it is that far off the target that you are not happy with it. Then the next thing that I would do is run a micrometer over your rings and base set up. If it is that far out you should be able to pick it up with your measurements and compare it against the point of impact from the shots you fired.

 

[lamiglas]

we bought (3) Rem 700's from cabelas several months ago, and my father in law had the same problem with his. I took the gun to shawn carlock and he looked it over and verified that the holes in the reciever are not straight. I called Remington and the gentlemen wasnt surprised at all. he said it happens sometimes and if i sent it back they would ship to cabelas a new rifle. cabelas said they would take care of all of that for me. bottom line, the gun shot well, so our option was to have a gunsmith do some work, or go back to the rear windage leupold ring ( the cheapest option, so the one he chose). with the adjustment in the base, he hasnt had any problems since. The gun shoots very well.

 

[sdowney]

I did try another scope on the base and the same thing happens. And it's more like 3" off at 15 yards. I definitely don't have enough windage to make it right.

The rifle is several years old and I've had it worked over pretty good by a great gunsmith in Denver. Returning it to Remington isn't an option at this point.

It does sound like it's a receiver hole problem vice lousy base, doesn't it? Can a decent gunsmith fix that or am I stuck with discarding the base and rings and going back to traditional rings and bases?

 

[lamiglas]

It depends on how far it is off. I believe alot of the time, a smith can re-tap to a larger size and correct the problem.

good luck to you.

 

[sdowney]

Is it likely that it's the EGW base? Assuming it's not and it's the taped holes that are misaligned, what are my options if the smith can't fix the receiver? Is there such a thing as a one or two piece, 1", 20 MOA, windage adjustable base that can take heavy recoil?

BTW, I did measure the error and it's about 18 MOA. I only have +/- 15 MOA adjustment on my scope.

 

[Topshot]

Check out Burris, I am sure they make one that takes their ring inserts.

 

[Coyboy]

Buddy take a deep breath and read this post. I will explain what is most likly your problem. You need to think a little to grasp what I'm telling you.

1st off chances are it's NOT the egw base or the reciever holes. Yea I know now you think I know **** about your problem, keep reading.

9 out of 10 remington recivers " roll off " to the right and the rear, ON the REAR reciever ring. What this means is as you tighten that alluminum rail, it is twisting to conform to the surface dimensions on the reciever.

So what you end up with is a base that twist to the right at it's rear end. When the rings are set on the rail the rear ring will lean right. this will be exagerated the taller the ring you use. So what this caused was a scope that points to the left when set in the rings.

This is why you see smiths advertise "epoxy bed picitinny rail stress free" when I do this to a rifle/rail I end up with a flat untwisted rail, thus rings that line up and lap in much easier, and a scope that is centered on the barrel.

the reason for this roll off in the reciever ring is due to the way remmy polishes the recievers during manufacturing. High polish SS or blued recievers are usually a little worse than the parked recievers. If you don't believe me take the scope and rings off. remove the base, then set the rail back on the reciever, look at the right rear corner, slide a feeler gauge in the gap. Try installing only the rear most screw and tighten it down. Then you can watch the front of the base rise off the front reciever ring.

One other thing to consider is that the barrel or action thread tennon/recoil lug, is a little ascew and there is somthing in that joint forceing the barrel to point a smidge to the right.

Hope you figure it out without spending more $$$

 

[sdowney]

Cowboy, thanks for your input. What would you suggest from here? Could a decent smith in Boise epoxy bed the base? Is my EGW base still good or is it likely a gonner? Once expoxied in, I take it it's a permanent fix; that's OK. Also, will that expoxy bedded base be strong enough to handle a .300 RUM hunter with a big scope?
Or, would you suggest I cut my losses, and go with some kind of two piece base with windage adjustment like a Leupold and allow the Seekins rings and EGW base to collect dust in the 'almost useful pile'?

 

[Coyboy]

Scott, if I were you I would take the mounts off and eliminate some of the questions.
1. line a 2 foot long straight edge down your screw holes to see if they look parrellel to the barrel.
2. Take the base and see how much roll or twist is in the thing when tightened, A precision level or parralell. or somthing that is perfectly flat can be laid on the base when it is tightened down to see how much rocking takes place.
3. Unless the smith actually is aware of the problems with this type of instal, he may just put epoxy under the base and tighten the screws causing the same problem but gluing your base.
4. The base is not perminent when epoxy bedded. Once the screws are removed a couple of smacks with a plastic mallet will pop the base off the reciever, then the remaining epoxy shim can be scraped off. Also. I always epoxy bed the rail AFTER the action is bedded to the stock and tightened in properly. I will try and find a post I have here about installing bases with bedding and provide a link.

Your base is still good it will flex back to normal when the screws are removed. Yes it will be stronger with the epoxy and will handle the recoil.

 

[Coyboy]

One note not in this post, avoid epoxy with metal flakes in it for this application, acraglass gel works the best.


05-16-2009, 10:06 AM
Coyboy
SPONSOR
Find Me on the Map Join Date: Jan 2005
Location: Center of the State, Pittsville, Wisconsin
Posts: 924

Re: Scope Installation

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Here's how I set up a new gun in the shop.

90% of the rifles get a picatinny rail. They are epoxy bedded to the reciever and shimmed if necessary so that the rail does not "bend" to conform to a reciever that is not dimensionally accurate, during the bedding process the screws are waxed but the rail and reciever are clean so the epoxy bonds them but the screws can be removed degreased and lock tited the next day. You must first find a front and back screw that will hold the base in the proper positon to equal out the tolerance differences and use those 2 screws when setting the epoxy, tighten them down so you get metal to metal contact. Do not overtighten or you will twist the rail. The goal is to keep the rail FLAT so that the two rings when mounted are in the same axial plane. The epoxy acts as a shim so after it sets and the screws are reinstalled it tourques up without twisting or putting stress into the system. If the base twist that offset will be magnified into the rings when they are set. If you don't think the reciever to base fit can possibly be ascew set a rail on a remmy and tourqe down the far rear base screw with no others installed. The front of the rail will lift off the reciever and point skyward around .005-.015"

The Tac rings are then set on the base in the proper position for the scope/eye relief that will be needed. The rings are torqued to the rail, while paying attention to their alignment. The ring tops stay off for now. The easiest way to tell if the rings are truelly aligned is to take your lapping bar charge it and do a quick lapping, clean off the paste and check the rings. If everything was done properly up to this point and your rings are of high quality it should take very little lapping.
Once the rings are lapped true, I determine weather the ring tops need to be lapped, Usually I do not lap the tops, unless there was a serious alignment problem with the bottoms,(ussually the cheaper the ring base set up the more lapping is sometimes required)

The only time I lost clamp on a set of rings was on some *** ruger factory rings that were seriously f'ed. After lapping I milled off a little material on the ring bottoms where the screw tappings are, to give it clearance to clamp.

Leveling the scope is the easy part. I drew 2 lines with a 4' level on the far wall of the shop. Level the gun in a clamp with a level acrost the bolt race way, where the bolt handle cutout is or on the rear lang flat. Then rotate the scope until the hairs line up with your plumb line on the wall. double check and tourqe, double check after tourqing tight, attention to detail gets it right. Putting a anti-cant level on the tube in this set-up works well also.

You can confirm by placing a target at 100 yards draw a perfectly verticle line on the target. Aim at the bottom of the target on the line, holding your cross wire perfictly verticle with your line, shoot a group. Put 20 minutes of ellevation on the scope and shoot again, your second group should be straight above the first (20"), if you held your cross wire perfectly verticle. If not Rotate the scope until it does.
__________________
Jim See

Center Shot Rifles llc.
Making Rifles Accurate
Center Shot Rifles (Pittsville, WI)

 

[sdowney]

You must first find a front and back screw that will hold the base in the proper positon to equal out the tolerance differences and use those 2 screws when setting the epoxy. Do not overtighten or you will twist the rail.

Jim, will the EGW supplied screws most likely work, or do I need to find a whole slew of screws somewhere?

So, just tighten until the screws start to take hold, probably 2-3 in-lbs? Epoxy, and then re-tighten at 15-20 in-lbs?

What are the cons of using $4 J-B Weld vice the $32 it will take to get Acraglass delivered from Brownells?

As I'm currently on the road working for Uncle Sam, and running short on time before hunting season, I'm thinking I'll order the supplies and have a go at it when I get home. Would you agree it's not an insurmountable task for a novice DIYer?

 

[Coyboy]

The screws are waxed so no epoxy sticks to them, plug the 2 holes that you will not be using with clay so they don't fill with epoxy.You put the epoxy between the bottom of the rail and the top of the reciever. Then you set the rail over the screw holes, and instal the 2 waxed screws (johnson paste wax, or grease will work as well) Tighten just so the rail is making contact with the reciever at the high points. You want the epoxy to remain between the reciever and the rail to act as a leveler and shim. clean off the epoxy that squeezes out. Let this set 24 hours. remove the 2 screws the base will still be stuck to the reciever leave it that way. With pipe cleaners degrease the holes and clean out the putty. now instal the screws with lock -tite to proper tourqe, done.

If your rail fit is really bad you may want to cut a thin brass shim to put under the right rear corner to help keep the rail as level as possible to the reciever bolt raceway.

Yes egw screws are fine. sometimes the very front screw needs to be shortened so it dosen't bottom out on the barrel threads.

JB should work.

 

[sdowney]

To Coyboy and the others who helped:

Conclusion: I took the rifle to a respected smith here in Boise and I had both issues with this rifle.

The factory receiver screw holes were misaligend. Jim tapped new, larger holes that actually lined up with the barrel. But the scope still canted left.

Then, he expoy bedded the aft portion of the rail to minimize the twisting to the right when the screws were torqued down.

These two fixes moved my scope from 18 MOA to the left to 1/4 MOA to the right!

Thanks again.