[sirtirithon]

So I finally mounted a scope on my M1A yesterday and took it out today. I thought I had an in spec receiver because my ARMS 18 mount appeared to mount fine. The scope I mounted isn't exactly high end, I'm aware of this. I installed a Leupold VX1 using Warne low quick detach rings. I dont have a big budget right now and just wanted a good hunting scope for the upcoming season. Still it isn't a cheap scope set up either.

Trouble is I ran out of both elevation and windage. Several of you told me this would probably happen. Dang!. I'm getting nice tight 2" groups at 100 yds but they are 4" to the left and 3" high from the bullseye and I'm bottomed out on adjustment. I knew this might happen. Question is what now? Elevation doesn't bother me, but windage being off isn't good at all. There is a reputable gun smith in my city that builds custom rifles and was an armorer in the USMC for several years. I have seen some of his M14 builds and they are fantastic. He was the one who recommended the ARMS 18 mount to me. I'm thinking I might talk to him about mounting it correctly. I don't feel comfortable grinding on it and wasting more ammo trying to get it right. Is this an expensive job to have done? What do you guys recommend? Should I sell the Leupold and just buy a new scope with more MOA adjustment?

 

[Marine1]

STOP! Opinions will not be in short order, but at this point you could continue to spend ALOT of $ chasing a potentially inexpensive fix. Go see the former USMC (some of the finest in the world if I do say so myself, Semper Fi) He should be able to take a look and make needed modifications for much less $ than starting over again. My .02 cents!

 

[Rawnerves]

I say if you have a good USMC gunsmith near you, what are you waiting for? Switching scopes, rings, and things around can get very expensive, been there done that.

 

[boomer1983]

Iv heard of this problem before and am wondering if its receiver manufacturer related or is it possibly a mount issue? I just mounted the arms 18 on a lrb receiver and havent put the scope on it yet but Im concerned when I do I might experience the same thing you have at the range. Is shooting and sighting it in the only way to tell if its missalinged? I hope its not a dumb question but I figured someone here could set me straight.

 

[BLACKTAIL 8541]

Iv heard of this problem before and am wondering if its receiver manufacturer related or is it possibly a mount issue? I just mounted the arms 18 on a lrb receiver and havent put the scope on it yet but Im concerned when I do I might experience the same thing you have at the range. Is shooting and sighting it in the only way to tell if its missalinged? I hope its not a dumb question but I figured someone here could set me straight.

Haven't had any problems with the ARMS 18 mount and LRB receivers. So dont worry about it untill there are problems.

As to the OP. take it to your USMC armorer and let him do the work to correct the issue. He can probably do it in an hour or less.

 

[Charlene32]

i had this same problem with my leupold. i had to unscrew the set screws in the elevation knobs with and allen wrench to reset the zero-stop. does you scope have this function? if it does then i bet that is your problem. there is nothing cheap about a leupold. they make good optics.

 

[Al Mack]

To check the mount alignment. Get a 3/8 dowel, with the scope off set the dowel in the center of the mount to see if your off and how much. I hope this helps, good luck.

 

[Bimmer]

I'm getting nice tight 2" groups at 100 yds but they are 4" to the left and 3" high from the bullseye and I'm bottomed out on adjustment...

I don't feel comfortable grinding on it and wasting more ammo trying to get it right.

This isn't so bad. You're only 3-4moa off... some of the real problem cases here are 15-20moa off.

I'd try just shimming the mount and/or the rings.

You'd be surprise how much difference a couple pieces of aluminum cut out of an old pop can (or a stripe of electrical tape) would make when placed inside a scope ring... if my math is correct, then .10" would make a 6moa difference.

I'd use pieces big enough to wrap halfway around the scope, and I'd put them at the lower right at the front, and at the upper left at the rear. This should move your point of aim significantly to the upper left (where your point of impact is).

Should I sell the Leupold and just buy a new scope with more MOA adjustment?

Absolutely not. This would just be a band-aid fix... Admittedly, the shims would only be a band-aid, too, but at least they're basically free.

Bimmer

 

[sirtirithon]

Thanks for advice! I will swing by the gun smith's shop tomorrow and see what he says. Not sure how a ARMS 18 that fits correctly should look but it isn't fitting flush in the receiver groove. There is a paper thin gap left. I'm thinking that's where the windage problem is. Elevation could be the low rings. But that's not a big deal. I'm hoping he can fit it for a reasonable price and I can finally enjoy a trip to the range. I don't think the scope is at fault, its brand new.

 

[Bimmer]

... it isn't fitting flush in the receiver groove. There is a paper thin gap left. I'm thinking that's where the windage problem is.

The gap would have to be more than paper thin... you're off by at least an eighth of an inch, which is pretty significant.

Elevation could be the low rings.

No, that's not how geometry works. Your problem is NOT that the scope is offset, the problem is that the scope isn't close to parallel.

Elevation could be the low rings. But that's not a big deal.

Really, it is a big deal, and you should fix it.


Try this:

If you can see your iron sights with the scope mounted, then set up the rifle on a bipod or on sandbags or whatever, and aim it at a target or something using the (zeroed) iron sights.
You can do this in your backyard with your unloaded (repeat: UNloaded) rifle.

Then sight along the edge of the scope mount and see where it points. This isn't very accurate, but if you're as out of whack as you say, then it's probably pointing down and to the right from where your iron sights are pointing.

If the mount seems straight, then you might take a close look at your rings and scope...

Bimmer

 

[JMGlasgow]

Burris Signature rings and inserts. Problem solved and inexpensive. Make sure to re-center the scope.

 

[lefty o]

placing shims inside the scope rings wil;l result in nothing more than a crushed scope tube!!!!!!

the simplest answer is the burris signature series rings.

 

[M1AallTheWay]

There are many threads on TFL which look at mounting issues with the ARMS mount, including this one. But because the fix often involves what amounts to custom fitting of the mount to the receiver, the best advice, as stated above, would be to have the armorer look at it first. The Burris Signature rings are a fine solution, and I've used them extensively, but if you can get it mounted properly, that'd be even better.

 

[Bamban]

Burris Signature rings and inserts. Problem solved and inexpensive. Make sure to re-center the scope.

+1 The cost effective and no downside option.

 

[bd111]

+1 The cost effective and no downside option.

There really isn't. May be Burris's best overall product. The inserts protect your scope's tube while securing it. Signatures succeed everywhere from rimfire to bigbore rifles and revolvers.

 

[Bimmer]

placing shims inside the scope rings wil;l result in nothing more than a crushed scope tube!!!!!!

Not true.

If he over-tightens the screws on the rings, then he'll crush the tube no matter what.

If he uses shims and tightens the screws properly (20 inch-pounds, right?), then it'll be fine.

 

[MajorJim]

Don't know if it will compensate for a 4 MOA difference at 100 yards, but lapping the rings might be a good idea.

Rings can have the ever so slightest deviations and not be perfectly rounded. In addition, when you mount the rings to the rail, and deviations in the mount will cause a misalignment between the front and back rings.

Lapping the mounted rings will make the MOUNTED rings concentric with one another and in contour with the scope.

Also take a hard look at the instructions for the scope - some will allow you to reset zero and adjust the set point for alignment.

I'd also check the mount - most of the older mounts were zero MOA cant, meaning they did not raise the point of impact. Some new mounts add 20 or more MOA in elevation to compensate for scopes runing out of adjustment at around 1000 yards.

We all know that bullets start to drop as soon as they leave the rifle. They why do trajectory charts show a rise in elevation? Because modern rifles are barreled with a slight upward cant. If the receiver and barrel mounting is not precise, the cant can be higher or lower (strssing the importance of precise alignment). That could be another factor at work here, but if it is an issue of the barrel threads in the receiver being off, absent a new receiver, you are left with compensating fixes, like shimming.

How does your rifle shoot just with iron sights?

 

[Charlene32]

thats what i said, and that is what i think the problem is. i am assuming that the leupold scope is new, and if it is then its a simple matter of resetting the zero-stop on the dials. the same thing happened to me with my leupold. i wish the OP would come back and say that is not the issue, because right now im convenced.

 

[sirtirithon]

Just got off the phone with Leupold. The VX1 scope does not have that function, to reset the zero. I explained my problem to the customer service rep and he actually knew all about the SAI out of spec receivers and ARMS 18 issues. He recommended the Sadlak measuring kit or the Burris rings with inserts. Gotta hand it to Leupold, they have great customer service. I gave the local armorer a call and he said it would run around $60 to fit the mount to my receiver but he wants to see it first. So I'm off to go get his expert opinion then depending on the cost of fitting the mount either sell my current rings and order the Burris or have the mount fitted. Thanks again! Ill post what he says.

 

[lefty o]

Not true.

If he over-tightens the screws on the rings, then he'll crush the tube no matter what.

If he uses shims and tightens the screws properly (20 inch-pounds, right?), then it'll be fine.

its a free world, but if you add something inside the ring, you risk ruining your scope.