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Strange shift in shot patterns with Lux... Help!

608 Views 11 Replies 7 Participants Last post by  kilroymcb
I've had my CZ-452 Lux now for several months. I shoot it quite frequently and am always impressed with its fine handling and shootability. However, one particular problem keeps vexing me and won't go away.

I have the Lux equipped with a 4x34 Kronos scope with a one inch tube, attached to the receiver via Millet angle lock scope rings. I usually shoot either Winchester Power Point 40 grain standard velocity, or CCI 40 grain standard velocity. I have the scope zeroed for 50 and 100 yards. Usually, I can drop every round into a 1.5 inch circle at 100 yards, centered on the point of aim. However, sometimes, with no predictable pattern, my shots will be thrown off in a tight group, about the same size, between 2 and 2.5 inches to the right of the point of aim. This isnt a string, or a couple of flyers... these are complete, well centered groups off to the right a couple of inches.

This one I took from a bad angle... but trust me, its off to the right, not straight up.

And here is a group over a great deal more shots.


I've had it happen from a cold barrel or from a hot one... with a clean barrel or with a dirty one. And I'm quite careful not to let my barrel contact anything, resting only the stock on the bench. The rings are quite tight and I've marked the windage and elevation drums so I'd know if they'd been moved. I've put well over 1000 rounds through the rifle now, so I think if it were poor shooting on my part, I could pin it down...

Does anyone have any suggestions as to what it could be and how it might be resolved? HELP!
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Are the action screws tight? Sounds like it is moving around in the stock or if the barrel is not free floated the stock contacting the barrel may cause this. These are the only things I can think of right now.

PS": Welcome to RFC...
 

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Discussion Starter · #3 ·
I can turn the forend screw maybe a quarter turn more before I fear damaging the head of the screw. Experimenting, I found I could easily slide a sheet of notebook paper beneath the barrel just in front of the rear sight mount. Obviously, I'm not at the range to see if tightening up the action screw helps any... but I wouldnt think that such a marginal amount would cause a dramatic shift like that. Any other suggestions? I'll give it a shot next time I head back to the range though.
 

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Discussion Starter · #5 ·
So, Nick, you're saying that the reticle on my scope may be shifting around? Do you know any fixes for this, other then replacing the scope? I really like the optics on this particular Kronos.
 

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Reticle shifting is a possible cause. Another way to check if it is really a problem : look through the scope while dry-firing (against an empty shell, for peace of mind). I've seen the reticle "jump" with the small vibration caused by firing pin impact. This is why Burris has the Posi-Lock option.

I don't know any simple way to fix the problem. Had thought of drilling and tapping a cheap scope to simulate the Posi-Lock, but hadn't gotten around to it.
 

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Another possibility - though it's never, never happened to me personally - is a tilted rifle.

I've seen some other guy line his horizontal cross-hair up parallel with the top of the target frame, which turned out not to be fully seated in the holes in the ground. Threw a very consistent group neatly off to the right, it did.

Jaywalker
 

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Discussion Starter · #9 ·
Well, I tightened up the stock screw as tight as I could to see if it helped the problem. Only effect was, it shifted the POI up by about 4 inches. No windage change. Sadly, I sheared the stock screw trying to loosen it again. Allen head screws in the mail :B
 

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The first, cheapest and easiest thing to do is swap out the scope with another that you know is OK. Just put on another scope and see what happens, sure sounds to me like this might be your problem.
 

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take the scope off and shoot open sights at 50...my special shoots better than that at 50 with open sights...so id have to say scope could be the culprit. could be wrong though. another thing would be to make sure your barreled action doesnt wiggle in the stock. my .17 was like that last time after shooting (didnt know it) but it shot where i aimed so i guess it didnt affect it...just weird if you ask me. i should check that again to make sure its hitting where it was after being tightened...
 
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