Scope failure, maybe

B

big bear

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I have an older Leupold VXIII scope that I suspect have failed. I had been getting 1.5-2" groups at 100yds with this scope (quite good for the old 303 it was mounted on). Then the groups became a bit erratic with unexplained flyers and now the impacts vary up to 1 foot ib elevation. Windage does not shift much at all. The mount is tight. I was just surprised that the elevation could fluctuate so much shot to shot with the windage not varying much if any. I want to blame th Lee No4 Mk2 because I am not an Enfield enthusiast.But the rifle is an as new Fazerkerley 1956. All the screws are tight.

So I thought I'd post this question before I change scopes and burn through some more ammunition. Just in case it's the old No4MK2 sudden onset wandering elevation syndrome familiar to everyone except me.:bangHead:
 
Korth is warranty repair. I will be sending it in if my test of rifle with a different scope shows that the problem isn't the rifle . Looking back on the scopes history I have had it for over 30 years b:, time sneaks up on you!
 
Keep us posted what you discover about that scope - is about a dozen of that era here - I have had Bushnell and Weaver scopes die on the range, but not a Leupold - first time for everything, though. If it turns out to be that scope, about the only "saving grace" was that it died when you were shooting at targets - not when firing at a once-in-a-lifetime buck!!!
 
Sun_and_Steel_77 said:
I agree with the above. Any Lee-Enfields I ever owned were not consistently accurate enough to test a scope.
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I would go with that! One of the Bushell Banner scopes that "died" was on a Parker Hale sporter No. 1 - my first time shooting my hand loads - got a rough cluster sort of near the bulls eye, then holes started to "walk" to the right - I think #13 or #15 was right off the right side of the paper (14" (35 cm) wide paper) I do not know if that was the scope or the rifle - is still in back of rifle closet as I brought it home that day (several years ago) - I never tried it again.
 
The older SMLE type 303's were renowned for scope or scope base failure. If it has one of the PH type rails spanning from the front of the action to the rear bridge, you may find that the mount screws have failed, or even been shorn off because the action is a rear locking and flexes each time it is shot until one day something gives. May only be one of the mount screws.

And it was also common for the scope to slowly creep forward over time as each shot flexing the base and rings caused the scope to move in the rings, only about a nats fat, each time. But over years and shots fired it may move. A lot of shooters would notice the scope moving over time and consequently tighten the crap out of their rings, and that would cause the scope to fail.
 
Another option is the barrel has worn out... so swap scopes on current rifle... and put current scope on another rifle of known performance.

testing both rifle and scope will get you answers easy enough.

Good luck

Jerry
 
As mentioned multiple times, easiest thing is to swap scopes and test again.
If it is pooched Korth has been excellent for repairs.
Wouldn’t surprise me I’ve had multiple scopes crap out. I’m guessing I put more rounds down than most.
 
Mystic Precision said:
Another option is the barrel has worn out... so swap scopes on current rifle... and put current scope on another rifle of known performance.

testing both rifle and scope will get you answers easy enough.

Good luck




Jerry
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The rifle is as new (other than factory test fire I am pretty sure it was not fired before me. I have put 150rds through it so I can't see how the barrel would be worn out. Mount is commercial mount which fits into the rear sight base with no alteration of receiver. Installed by a gunsmith . Mount is very stable . The drastic random vertical dispersion of the impacts with virtually no shift at all in windage is a clue to cause of problem .
i'm not just sure what it means.I've mounted a new scope and hopefully will get out tomorrow to test.
 
Let us know what you eventually discover. From your description in Post #13, sounds like you have a "no drill / no tap" type mount? I have one that also fits in place of the rear sight - a Parker Hale A21 base, but that required drill and tap for front receiver ring for the partner A20 base. And those PH bases pretty much need the PH rings to go with them. If it were me, I would be looking closely at that scope mount base, but then I would likely have mounted it myself - so lots of experience with my own "screw-ups".

FYI - if your rings are 4 inches apart, and you get 12" vertical dispersion at 100 yards, that can be caused by your scope lifting at front ring, or rear going down, or combination, that totals only 0.0133", which is ignoring any barrel whip or "compensation" that might be going on.
 
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Potashminer said:
Let us know what you eventually discover. From your description in Post #13, sounds like you have a "no drill / no tap" type mount? I have one that also fits in place of the rear sight - a Parker Hale A21 base, but that required drill and tap for front receiver ring for the partner A20 base. And those PH bases pretty much need the PH rings to go with them. If it were me, I would be looking closely at that scope mount base, but then I would likely have mounted it myself - so lots of experience with my own "screw-ups".

FYI - if your rings are 4 inches apart, and you get 12" vertical dispersion at 100 yards, that can be caused by your scope lifting at front ring, or rear going down, or combination, that totals only 0.0133", which is ignoring any barrel whip or "compensation" that might be going on.
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Mine is the BadAce Lee-Enfield NDT scope mount. I've already changed scopes but I will go over all the screws gain.
 
Potashminer said:
Let us know what you eventually discover. From your description in Post #13, sounds like you have a "no drill / no tap" type mount? I have one that also fits in place of the rear sight - a Parker Hale A21 base, but that required drill and tap for front receiver ring for the partner A20 base. And those PH bases pretty much need the PH rings to go with them. If it were me, I would be looking closely at that scope mount base, but then I would likely have mounted it myself - so lots of experience with my own "screw-ups".

FYI - if your rings are 4 inches apart, and you get 12" vertical dispersion at 100 yards, that can be caused by your scope lifting at front ring, or rear going down, or combination, that totals only 0.0133", which is ignoring any barrel whip or "compensation" that might be going on.
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Mr. POTASHMINER for the win. The lock plate on the mount had come loose.Had to put rifle upside down and use a flashlight to see the little tab. Thanks for all the suggestions .
 
big bear said:
Mr. POTASHMINER for the win. The lock plate on the mount had come loose.Had to put rifle upside down and use a flashlight to see the little tab. Thanks for all the suggestions .
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Nelson is one of our very best IMO!! He knows lots, not shy of sharing what he knows, no drama and a lot of common sense!!
 
Thank you for comments - to be seen, yet, if that was OP's only issue. I had come up with (I thought) an issue that was out of order, but had nothing to do with the symptoms displayed.

A CGN thread some years ago about a BSA m1917 conversion - new-to-rifle CGN owner was getting 4" or so groups at 25 yards - had tried multiple bullets and loads - no change. Discovered rear base was not matching to curvature to the rear bridge - that scope base had larger radius curve than the receiver - so likely could "rock" - so required epoxy bedding to stabilize - a good solution, except problems persisted. Turned out that bore slugged to .282" groove diameter, not the .277" that one would expect for a 270 Win. The CGN owner found that out by slugging that barrel, before he mailed that rifle to me - and I found same diameter when I slugged it here. Still sitting on shelf waiting for "inspiration" for a solution to that ... Is some Nosler Partitions in .277" - here for that BSA 270 Win - about the only exposed lead base bullets I could find in .277" - maybe those will swell up enough to fill that barrel size - to be tried, at some point. In my mind, unless it is capable of at least 1.5 to 2 MOA at 400 yards, is kind of pointless to have a 270 Win for hunting?

I am not adverse to a 270-7mm - I do not have similar - about 10 or 12 years experience taking deer with 7x57 - is only the 7 mm that I have - but that BSA rifle would also need the throat to be reamed, because, as is, can not chamber 270 Win brass with 7mm bullets in the neck - throat is too skinny - from cerrosafe cast, appears to be a "perfectly dimensioned" 270 Win chamber.

https://www.canadiangunnutz.com/forum/showthread.php/1863303-VERY-strange-BSA-problem
 
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Back from range. I used blue lock tight on every screw in mount and rings.and..... the rifle is back to behaving perfectly. So the cost of 2 boxes of ammo is my tuition fee for learning the obvious.l Thanks everyone!
 
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