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

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  #8  
Unread 08-03-2009, 06:47 PM
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Re: S.O.S.-New Scope setup looks 'left'...a lot!

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 $$$
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  #9  
Unread 08-03-2009, 09:41 PM
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Re: S.O.S.-New Scope setup looks 'left'...a lot!

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'?
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.338 Norma Mag, Stiller Tac338 & Rock Creek barrel
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  #10  
Unread 08-04-2009, 07:01 AM
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Re: S.O.S.-New Scope setup looks 'left'...a lot!

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.

Last edited by Coyboy; 08-04-2009 at 07:17 AM.
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  #11  
Unread 08-04-2009, 07:09 AM
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Re: S.O.S.-New Scope setup looks 'left'...a lot!

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
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Re: Scope Installation

--------------------------------------------------------------------------------

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 POS 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.
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Last edited by Coyboy; 08-04-2009 at 07:19 AM.
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  #12  
Unread 08-04-2009, 10:10 AM
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Re: S.O.S.-New Scope setup looks 'left'...a lot!

Quote:
Originally Posted by Coyboy View Post

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?
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.338 Norma Mag, Stiller Tac338 & Rock Creek barrel

Last edited by sdowney; 08-04-2009 at 11:08 AM.
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  #13  
Unread 08-04-2009, 06:09 PM
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Re: S.O.S.-New Scope setup looks 'left'...a lot!

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.
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  #14  
Unread 08-24-2009, 11:27 PM
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Re: S.O.S.-New Scope setup looks 'left'...a lot!

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.
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.338 Norma Mag, Stiller Tac338 & Rock Creek barrel
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