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Old October 5, 2014, 12:31 AM   #1
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*****need help with my leupold mk4*****

I recently purchased a Mark 4 LR/T 8.5-25x50mm (30mm) M1 Illum. Ret (TMR) and mounted it to my standard M1A. I've gone through 200 rounds of 168 gr .308 factory ammo (Nosler Trophy Grade) trying to get this thing dialed in.

When I originally zeroed the scope at 100 yards, I did so on full magnification and achieved a 1 inch shot group on center. I was hitting about 2-3 inches low at 200 yards (which is about right per the ballistics).

I have since been back to the range, because I wanted to zero the scope at 200 yards instead of 100. My first shot was 8 inches low on full magnification. Subsequent shots were all over the place (after adjustments were made).

I decided to back off back to 100 yards and re-confirm my zero. The full magnification was giving me a hard time locking down a shot group and getting on center. I decided to back off on magnification and put the scope on it's lowest power. My first three shots were a 1/2 inch group, and my adjustments to center were spot on after the first adjustment. I was repeatedly hammering 1/2 inch shot groups on center on low power.

But then I'd go back to high power and my shots would just be all over the place. The Marine Corps taught me how to shoot. I have several other scopes. This isn't my first rodeo...but what the heck is going on here? Could it be a faulty scope?

Your help would be much appreciated.
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Old October 5, 2014, 12:47 AM   #2
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Old October 5, 2014, 10:01 AM   #3
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I've seen shooters affected by the perceived movement exacerbated by higher magnification. Over compensation and "snatching" at the trigger when the crosshairs slide past the aiming point is common for those not used to higher X power scopes.
I have no idea whether this is part of the problem or if you have an internal scope problem.
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Old October 5, 2014, 10:19 AM   #4
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If the mechanics aren't in doubt then swap out the scope with one of your others that you know is good and check your mounts in the process. Shoot a group and see if it does the same thing or shoots better. That will narrow it down to a scope issue or not. If it's not a scope issue you need to start checking your rifle and ammunition.

If it's a scope problem send it back to Leupold and have it repaired or send it down the road for anogher scope. I would have started doing thing before you sent 200 rounds down range chasing your tail for no real results. I'm sure you'll have it sorted out in short order.
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Old October 5, 2014, 07:04 PM   #5
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It sounds to me like you need a more solid rest, and need to really take your time shooting the groups.

I use the legs off old pants to make bags that I fill with rice.
They aren't as heavy as sand, and do a good job of cradling the rifles.

Use a long bag for the front and a small one for the butt
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Old October 6, 2014, 12:11 AM   #6
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I've found I can shoot tighter at 100 & 200 yards with scopes on their lowest settings.
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Old October 6, 2014, 04:12 AM   #7
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Sounds like the OP didn't adjust parallax for the higher magnification. If parallax isn't eliminated at range, small differences in eye placement can show up as crazy groups on target.

As magnification decreases, the effect of parallax on target diminishes, which is why you don't see parallax adjustment on low magnification hunting scopes, but you do on airgun scopes (where shots are at short range and targets are tiny).

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Last edited by Jimro; October 7, 2014 at 02:53 AM.
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Old October 6, 2014, 09:04 AM   #8
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There are many factors that can affect the POI using a scope that high power at that distance. 1. Mirage, probably not the problem but a possibility. 2. Parallex is a probable culprit. 3. Mechanical issues with the scope are also very likely.
My Leupold bench rest scopes have spent a lot of time on the UPS truck going back to be rebuilt because they just would not group like they should. I have a Leupold Mark 3 that has to settle in when adjusted. It takes it 7 or 8 rounds to settle. It is on a hunting rifle, so it is not worth the aggravation of sending it in to have it fixed.
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Old October 6, 2014, 01:35 PM   #9
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Old October 25, 2014, 08:17 PM   #10
edward hogan
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That is one big-ass scope for use on an M1a... Even if you have Brookfield or whatever The Best scope base is. I had a Sadlak...

Problem is the M-14 wasn't made to shoot with glass, it is an adaptation. Got a custom stock with cheekriser? Got a bedded stock? How's your trigger in terms of tune?

Want to shoot a semi-auto with best possible precision? Get an AR-10 flat top and your bedding and scope problems go away. You also have better bolt lockup and precision potential. Stock bedding job on an M1a might last 1000rds or at most a year. If you are sentimental about the rifle you just have a lot of issues to deal with.

Doesn't make sense to me to have the $$ tied up in that scope for use on an M1a. That scope on a custom AR-10 will hammer all day long and give you repeatability when removed/restored.

Nice to have a Bushnell #74-3333 borescope-collimator to diagnose scope problems. As others have suggested, swap a proven scope and see if your problems go away. Get the collimating tool and Know for sure what is wrong.
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Old October 25, 2014, 08:42 PM   #11
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I am not a pro, but if you are puling half inch zoomed out I can't see how it could be faulty only at high-power. I am not discrediting you as a shooter, I just don't see how it's mechanically possible w/o err on your end. maybe someone who knows more about scopes can correct me on that.
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leupold , m1a , scope help , scopes , sighting in

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