M14 with wandering horizontal zero

Grizzlypeg

Grizzlypeg

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I have this frustrating problem with my M14s that is scoped. I'll bring it out to the range, fire a five shot group and get a decent group of say 1.5 to 2" at 100 yards with surplus ammo (it shoots even better with Federal 308 ammo), but it almost never remains centred on where I had it zero'd to last time out. Its always wandering to the left of the bullseye. So I adjust my scope, recentre it, shoot a nice group, put the gun away, and next time out, sure enough, its off to the left.

The mount is a smith 3 point mount, rings are Burris Signature Custom Zee's and the scope is a Burris FFII 3-9x40 that was purchased new by me,and has only ever seen use on the M14s.

Any ideas? Is it barrel temperature? Bedding of the receiver in the USGI stock? I doubt the scope mount is loose. If its a moving component of the sights, it would have to be something internal in the scope itself.
 
Could be the scope or the stock(wood?) is touching the barrel, intermittently, due to it taking on or losing moisture. Like LeeEnfieldNo.4_mk1 says, take off the scope. Sight in and try it. If it continues to lose zero, it's the rifle. Most likely the scope though.
Contact 'em for their Canadian warrantee shop. customerservice@burrisoptics.com
This is Burris' warrantee.
http://www.burrisoptics.com/warranty.html
 
Looks like I have some troubleshooting to do here, and some systematic trial and error on finding the source. I only shot the rifle for a short while with iron sights, found the results promising, and wanted to scope it to see what the gun's potential was. I've had good luck with that brand of scope on my bolt action rifle. The side mount has always looked troublesome to me. I'd better have a good look to see if its still lying flat on the side of the receiver. On the other hand, if the V on the base is to located itself properly with the groove in the receiver, how can it lie flat? The groove would have to be oversize or exact for it to lie flat, and if its oversize that would negate its precise alignment.
 
LeeEnfieldNo.4_mk1 said:
take the scope off and shoot it with irons for a while. If it still wanders, you have a problem, if not, its the scope.
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Exactly what I would do. The m14 is difficult to scope to say the least. Some mounts will not mate to some receivers, and some mounts are garbage to begin with. After that, you have all the same issues you could with any scoped rifle.

One thing that I have done in the past with mounts is to paint the inside of them with a sharpie. Then mount them, shoot them, and then take off the mount. The contact area is very small on some mount/receiver pairs.
 
I've double checked it, and all screws are tight. With the action out of the stock, its easy to view the mating of the side mount with the side of the receiver. It is flat and parallel with the side of the receiver when viewed from beneath. The rings are Burris and look foolproof. I'm wondering if its something to do with the barrel and / or forend pressure. I notice that I can press on the barrel band and shift the foreend ferule to one side, but not the other. So, what's hanging it up?
 
Grizzlypeg said:
I notice that I can press on the barrel band and shift the foreend ferule to one side, but not the other. So, what's hanging it up?
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well, your ferrule/barrel band contact should be smooth, and the stock ferrule should not contact the gas cylinder. I am not sure what you mean by moves one way, but not the other, but I'd fix that out of principle.

I still think a range session with irons is the first step though.
 
carbonrod said:
well, your ferrule/barrel band contact should be smooth, and the stock ferrule should not contact the gas cylinder. I am not sure what you mean by moves one way, but not the other, but I'd fix that out of principle.

I still think a range session with irons is the first step though.
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I'll have to take the handguard off and get a better view of what is allowing me to flex the forend in one direction but not the other.

I'd probably need a couple of range sessions with irons only to see if the problem repeats. For some reason the pattern seems to be that I take the rifle out of the case, shoot, rezero, shoot a while and put it away. Then next range session, sure enough, its lost zero in the horizontal plane. Its a pisser because I find the rifle shoots good consistent groups, its just that the centre of that group keeps wandering despite using the same ammo.
 
With the scope mount removed and the hand guard off, I can see what may be the cause of the problem. The barrel is not centred down the barrel channel. At the very end of the forend of the stock, you can see its closer to the right hand side. In fact, there is just a hair's clearance between the right side of the stock and the gas cylinder. I have no doubt that it may well be touching at times and pushing the barrel left. The part of the stock that is touching the gas cylinder is the thick fibreglass aft of the ferrule. The ferrule itself doesn't touch anything as its larger in diameter, but the stock's narrow channel not being centred around the gas cylinder is what I was feeling when I could push the barrel left, but not right. Couple of thou right and it touches the gas cylinder.

So, do I grind out some of the offending stock, or bed the action so as to centre it? I'm thinking the latter would put more even pressure on the barrel via the barrel band.
 
Grizzlypeg said:
So, do I grind out some of the offending stock, or bed the action so as to centre it? I'm thinking the latter would put more even pressure on the barrel via the barrel band.
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The progression of tweaking your rifle toward what is laid out by the AMU manual will have you do both if you continue down that path.

For now, I would route out the area of the stock that is touching, as well as the stock ferrule.

If this is not a norc stock that we are talking about, I would be looking at barrel alignment before modifying the stock, however.

I wouldn't be in a rush to bed it until you are sure that you want to keep the rifle as is, and in the stock it is bedded to.
 
Thanks for the advice Carbonrod. Its in a USGI fiberglass stock. The more I look at it and tighten and loosen the trigger group, I see how its off centre. I thought it might be the plastic buffer, as that's awefully close or touching the stock, but I removed it and it makes no difference. I'd need to remove a little of the stock where the receiver hangs down into it, to allow it to shift in the direction I want. The gas cylinder could well be touching the metal stock ferrule, the more I look at it. The barrel is aligned pretty good, its as close as the eye can see. The gas piston's rod lines up perfectly with the oprod. I'd need to centre the barrel in its channel as I allow the bedding compound (JB weld?) to set up on the receiver. I could make up a thin spacer out of wire and wrap that around the gas cylinder and barrel, or make a V out of wire and put that beneath the barrel to hold it centred. What do you think?
 
I bedded the receiver using JB weld, shoe polish as release agent. Preloaded the barrel tension using a short piece of coathanger, ala Gus Fisher's method. Wrapped paper round the gas piston cylinder to force it centered in the stock. Polished the ferule so it would slide smoothly and put some grease between it and the barrel band. Remounted the Smith M21 mount, put the scope on Leupld QRW rings so I could easily remove it and shoot with irons, unimpeded by the scope rings cross bar that half impedes the view through the Smith's "see through" scope base.

When I got to the range, I was unable to zero the scope on the shots. I couldnt' dial enough left into the scope to get it on centre. Looked it all over, scope base was flat on the receiver along its length. No gaps at the bottom of the base to receiver and parallel. Yet, something wasn't right. I could see from above view, the scope base wasn't parallel to the receiver and barrel. Not at its bottom, where the bolt passes through, but up top where the rings mount. I could see its right hand edge wasn't parallel with the op rod, it angled left. That would make the gun shoot right.

Scrounged up enough tools to disassemble it all at the range. Carefully reassembled it, and voila, it was now seemingly parallel. ????? I have no idea what changed. Only thing I can think of would be either the securing at the stripper clip guide, or the front screw that presses against the receiver, was somehow jacking the top of the mount over to the left.

By the time I could get it back on, and light was failing, adjusted and shooting at 100 yards, I manage to put 3 shots through the 3" bullseye and one just outside it. No time to test further. I have to admit, I don't trust this setup. Either the scope base is extremely tempermental on install or the scope is wonky. I think I'll be taking the base off again and trying to see what sort of conditions can cause it to move laterally.
 
Hungry, iron sights are far more reliable by a long shot. They may not be as precise in aim, but they hold zero more reliably. The Smith mount looks like a winner, but like any 3 point mount, its a rube goldberg affair.

Northman, I might end up pulling a scope off another rifle and testing it on the M14. At some point that's going to be a wise move.

I'm wondering if either 1) during the process of turning the cammed bolt bushing that forces the mount rearward into the stripper clip guide 2) while tightening the screw that goes into the stripper clip dovetail, its possible to pull the mount crooked. What if the stripper clip guide groove or its face, isn't perpendicular to the rifle bore?

My guess, and it dangerous to guess, is that my experience at the range of being unable to get the scope on paper initially, shows some fly in the ointment. When I compared the view through the iron sights to the scope cranked all the way over to the left, I couldn't get it boresighted, let alone on the paper. That shows a significant problem lies in the scope or mount, and not the rifle, that I shot two bullseyes with using iron sights. Some good light and carefull observation, and I should be able to figure out if there is a way this mount can go wrong and not seat properly.
 
Ok, spent an evening at the range with the rifle to get a handle on this problem.

Shot 3 five shot groups with the scope. 2/3 of the groups look identical. First shot a bullseye, next four climbing and to the right. Worst scope group was slightly over 5" at 100 yards. But why the bulleye and near bullseye on every first shot?

Final group, 5 shots with iron sights. Light really starting to fade. Best group of the night despite my inabiliity to really see the target, just the white paper. No high and to the right, most shots edging on the bullseye, a pretty symetrical random cluster 2.5" maximum. 4/5 formed a nice little group of about 1.5" One went low for some reason and opened it up to 2.5". Its hard to judge elevation when the front sight covers so much of the paper. So that's my excuse. I can't understand why the scoped shots would be so piss poor.

I have around 400-500 shots on this scope. Its a Burris Fullfield II, made in the Phillipines. Maybe its given up the ghost?

I have no doubt now, the scope and or mount is holding me back. The iron sights don't show the same patter at all that the scoped shots are.
 
"...Its in a USGI fiberglass stock..." That eliminates the stock taking on moisture at least.
"...why the bulleye and near bullseye on every first shot?..." Cold barrel.
"...No high and to the right, most shots edging on the bullseye, a pretty symetrical random cluster..." Proves it's the scope or mount. Most likely the scope. Burris used to be really good scopes.
 
I'm pretty disappointed if its the Burris scope. I believed all that ballyhoo about steel on steel, double springed mumbo jumbo. I'm starting to think that scoping my M14 is pointless. I enjoy shooting it with iron sights and I have other scoped rifles that shoot far more accurately. I took the wise advice that if you simply want an accurate semi-auto, get an AR15.

I might just put the Burris scope onto my 300WM temporarily and see if it shoots accurately and holds zero. If its no damn good, I'll send it in for warranty. I have one on my 308 bolt action rifle and its given me no problems whatsoever, but there's a lot more metal clanging on an M14 with both the bolt opening and closing. That might rattle a scope far more than straight line magnum recoil. There's part of me that is actually afraid to put a decent scope on the M14 for fear it will do the same to it. The smart thing to do would be swap the scope from the 300WM onto the M14 and the Burris from the M14 onto the 300wm and see which one goes wrong.
 
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