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Author Topic: Point of impact changes  (Read 9003 times)

Offline 300rum

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Re: Point of impact changes
« Reply #15 on: October 07, 2015, 12:05:35 PM »
Your point of impact should not change from day to day.  I have scopes that I have not touched in a decade and they shoot exactly the same with the same lot of ammo, I don't have to make any adjustments.  I would be looking at the mount and scope. 

First range day I zeroed at 200 yards. Then I shot small steel targets from 300-550 yards all day long. Second range day I had to make some minor adjustments but was at least still on paper at 200 yards.

Offline Bob33

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Re: Point of impact changes
« Reply #16 on: October 07, 2015, 12:05:55 PM »
My guess is the scope got bumped in transit. A 6 MOA shift is enormous and I cannot envision any environmental factors that would cause it.
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Offline jaymark6655

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Re: Point of impact changes
« Reply #17 on: October 07, 2015, 12:09:53 PM »
temperature difference and a really sensitive powder?  Maybe the swing in  chamber pressure is causing the bullet to leave the muzzle at a different point in its vibration or recoil?

Pressure changes with altitude, but temperature and humidity also change it so an increase in altitude of 3000 physical feet might be effectively a lot more if you sight in at sea level on a really cold day with no humidity and then climbed 3000 feet higher and shot on a really hot, humid day.  I can't imagine any change in weather that would cause that much of a shift though.

 :yeah:

What powder are you using?  If you're not using a temp stable powder you could see that much shift.  What were the environmental conditions when you zeroed verses where you are shooting now?



Not a chance. If this is true,rifles would make better clubs.

I just heard a story about some scopes that once adjusted, you could sit there and watch the turrets turn back out or maybe it got bumped especially if they don't lock or something is loose somewhere.
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Offline Bean Counter

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Re: Point of impact changes
« Reply #18 on: October 07, 2015, 12:12:48 PM »
My guess is the scope got bumped in transit. A 6 MOA shift is enormous and I cannot envision any environmental factors that would cause it.

It was in a soft case and got buried under other crap for the long, LONG drive, and also shifted around a few times   :o

Offline Bob33

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Re: Point of impact changes
« Reply #19 on: October 07, 2015, 12:15:21 PM »
My guess is the scope got bumped in transit. A 6 MOA shift is enormous and I cannot envision any environmental factors that would cause it.

It was in a soft case and got buried under other crap for the long, LONG drive, and also shifted around a few times   :o
As a standard practice, I always (try to, at least) fire a test group after travelling to ensure the POI has not shifted. Hit Shappens.
Nature. It's cheaper than therapy.

Offline jasnt

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Re: Point of impact changes
« Reply #20 on: October 07, 2015, 12:23:19 PM »
Sounds like a scope base is loosening up to me. Should not be that much shift even with temp changes condition changes or barrel contact. Maybe scope isn't tracking right?
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Offline JimmyHoffa

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Re: Point of impact changes
« Reply #21 on: October 07, 2015, 12:24:32 PM »
My guess is the scope got bumped in transit. A 6 MOA shift is enormous and I cannot envision any environmental factors that would cause it.
Probably first guess too. Next might be a change in the stock or bind. How is the rifle bedded/floated?  Is the stock wood?

Offline Bean Counter

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Re: Point of impact changes
« Reply #22 on: October 07, 2015, 12:26:27 PM »
Quote
As a standard practice, I always (try to, at least) fire a test group after travelling to ensure the POI has not shifted. Hit Shappens.
That's really all I had to do: the 25 yard battle zero. I shot two rounds at 25 yards and saw that I was 1.5" low at 25, ergo 6" low at 100. Ergo 24 clicks @ 1/4moa adjustments. Fired two more rounds and was spot on. Filled 5 out of 6 of my tags with ease at 200-400 yards after that.

Unfortunately this lesson cost me a really nice pronghorn on a premium quality unit. but I'm glad I didn't wound him being so far off. Its not the goats fault that the hunter is the idiot. I wound up plugging an average buck and will chalk it all up to a learning lesson  :rolleyes:

Offline Bean Counter

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Re: Point of impact changes
« Reply #23 on: October 07, 2015, 12:27:34 PM »
Probably first guess too. Next might be a change in the stock or bind. How is the rifle bedded/floated?  Is the stock wood?


Stock wood. I don't think its glass bedded or anything fancy like that.

Offline Bob33

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Re: Point of impact changes
« Reply #24 on: October 07, 2015, 12:29:34 PM »
Well, you know BC that a few members on here do believe you may have a loose screw.  :chuckle:
Nature. It's cheaper than therapy.

Offline fisheral87

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Re: Point of impact changes
« Reply #25 on: October 07, 2015, 12:37:02 PM »
I recently had two screws back out on me around the action on my Weatherby.

Also check the bedding, 7mmFan had a similar situation with his model 700 where the stock was expanding/contracting and throwing him off.

Al

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Offline Bean Counter

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Re: Point of impact changes
« Reply #26 on: October 07, 2015, 12:39:17 PM »
Well, you know BC that a few members on here do believe you may have a loose screw.  :chuckle:

 :chuckle: Post of the day right there!  :tup:

Offline jaymark6655

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Re: Point of impact changes
« Reply #27 on: October 07, 2015, 12:41:50 PM »
One more theory:  Wet WA to dry WY with a wood stock, it shrank loosening your action screws.
20 Zardoz Points!

"That's the reason we pay $25 for a recoil lug made by a professional instead of one for $0.50 made by Micheal J Fox using a dremel!"

"Women should be treated the same as a French Rifle, dropped at the first sign of trouble."

"Fair is a meaningless word taught to young children."

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Re: Point of impact changes
« Reply #28 on: October 07, 2015, 12:48:50 PM »
I'm currently residing in Arizona

Offline coachcw

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Re: Point of impact changes
« Reply #29 on: October 07, 2015, 01:00:27 PM »
my bet is a loose base screw

 


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