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Point of impact shifted!! What caused this?
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<monyhunter>
posted
I don't want to make this a long drawn out post, so I will get right to the point.

Here is what I used for my deer hunts this year.

Tikka Master Synthetic
24" barrel
7mm Remington mag
Tasco High Country scope 3x9x40mm
WW Super brass Neck sized only (third loading)
Federal GM215M match primer
Barnes140 XLC XBT
Reloader 25 = 70 grn
loaded just off the lands

In working up this load for this years hunts I as able to dial this set up to shoot 1" groups, 2" high at 100 yards. I used this to take two whitetails, the furthest shot being about 150-180 yards.

I still have elk to go this year and so I wanted to make sure my load was still go for the fist shot out of a cold barrel. I also was going to test some other loads after that. So I took three of my "hunting" loads out to the range.

First shot ------------- 6 inches high, 2.5 inches left.

So I thought maybe just the cold barrel messed things up. But the next shot was also way off and the three shots grouped about 3 inches!!!! Man, what the hell?

I tested my other loads and they to were way high and to the left.

Is this what you start getting with a piece of crap scope, or is something else going on here?

If I hadn�t already pushed the limit with the wife this year, I would just run out and get a veri-X II for $189.

------------------
Monyhunter

 
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Picture of Bob338
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With any radical shift in point of impact the first thing to suspect is the scope, or its mounts. Second thing is a warping stock. Don't know your firearm but even plastic and fiberglass stocks will warp and cause a problem like you have. Wood is particularly bad as most wood in factory rifles isn't properly sealed to start with. Humidity changes will affect it greatly.
 
Posts: 1261 | Location: Placerville, CA, US of A | Registered: 07 January 2001Reply With Quote
<BMG>
posted
monyhunter,
I was shooting my 32" barreled 45-70 at the range yesterday and did some tests that you might find interesting. I shot my known load at 100yds while resting the forearm on the bags and holding the gun only with my shooting hand. Four shot groups 1.5" (405gr cast bullets, Fed GM210M, and 37gr IMR 3031) is normal with this load/gun and all was well. I then rested my hand under the forearm and gripped the rifle with both my hands and fired another four shots, well...
3" low and to the right was where they went in a 4" group.
Moral of the story: Check your grip. Different grips produce different POI. Hope this helps.
 
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<Mike M>
posted
Could well be the scope. But I would double check the seating depth. The Barnes bullets usually like to be seated about .05 off the lands. If they are seated against the lands pressure can go up significantly and accuracy will go straight to Hell.
 
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I suspect that big belled scope took a whack!! that why I like stright tube 20MM scopes like the 1.5x5 Leupold on hunting rifles. they don't stick out far beyond the front ring (1/2") and believe me that makes a difference...Took me a long time to figure that out...

Next could be the stock warped.

------------------
Ray Atkinson

ray@atkinsonhunting.com
atkinsonhunting.com

 
Posts: 42309 | Location: Twin Falls, Idaho | Registered: 04 June 2000Reply With Quote
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With the one and only Tasco scope I have used much, just changing the power from 3 to 9 power would cause the POI to change about that much.
Second guess would be the mounts, a loose screw or a broken screw.
Third, a loose action screw.
Any one of these, or a combination, could cause such a shift in POI.
 
Posts: 1372 | Location: USA | Registered: 18 June 2000Reply With Quote
<whales>
posted
When you were shooting was the barrel or the stock on the sand bags. It does make a differance
 
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<monyhunter>
posted
Bob338 = I don't think it could be the stock. Well in fact I did take the stock off the last cleaning round to get the dust off. Maybe that is it.

BMG = I was gripping the rifle the same way I always do to the best of my recollection. I do agree that any variation could cause the problems I was having. I will keep this in mind this weekend when I test some things out.

Mike M = I could not be the seating depth as the three shot were from the exact same loadings as I had used to sight the gun in with. They were also the same "lot" of loads I used to take my two whitetail. I don't know how far off the lands the bullets are seated, but I take them about 1/2 turn off the lands. Not exact science, but they "did" shoot straight.

Ray = I think it may be the scope. I have had this scope for about 7 years, so it may just have given up. To test this theory I am going to load up some 140 grn Ballistic Tips and shoot those this weekend. I have never had anything but stellar groups with the ballistic tips. My thought is that if the gun/scope can still shoot a nice group with the noslers, then it must have been something other that the scope.

JMac = Yes I think the scope is "lower" quality. I have been happy with it so far, but if it really is the scope I will be "upgrading" from here on out.

whales = see my response to BMG.


Thanks everyone for the help so far. I will be testing again this weekend and will post the results for ya. Part of me hopes it IS the scope so I have an excuse to buy a new one.

------------------
Monyhunter

 
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What was the temperature readings before and after the problem...
 
Posts: 439 | Location: Quebec Canada | Registered: 27 August 2001Reply With Quote
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monyhunter,

I had a similar experience to yours by just changing bullets.

I have been shooting Barnes X 300 grain bullets in my 375/404 for a number of years. They shoot very accurately in my rifle.

Earlier this year, I was loading some ammo for our hunt in Zimbabwe, and noticed that Barnes have changed the design of thier X bullets.

I used teh same components as with the old style bullets, but found the new ones would shoot about 8 inches to the left!?

I could not beleive it at first, so loaded a couple of loads with the old style bullets. Sure enough, those went excatly as they should.

I re-adjusted my scope and left it at that. The new bullets worked just as great as the old ones.

------------------
saeed@ emirates.net.ae

www.accuratereloading.com

 
Posts: 69652 | Location: Dubai, UAE | Registered: 08 January 1998Reply With Quote
<Boyd Heaton>
posted
My 300 Ultra on a clean barrel alway's spit's the first one about 4 inches high and 2 inches to the right and takes about 5 shot's to settle down.

------------------
My wife told me if I buy another gun she would leave me.I hope the door does not hit her on the way out!!!!!

 
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Picture of Dutch
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My Tikka also reacts pretty interestingly if you change the torque on the action bolts. Wouldn't be surprised if taking the gun out of the stock wasn't the culprit (but I still vote for the scope!). HTH, Dutch.
 
Posts: 4564 | Location: Idaho Falls, ID, USA | Registered: 21 September 2000Reply With Quote
<Reloader66>
posted
You stated you took the rifle apart. That fact is certain to change POI. You can never get the same tension on the actions screws after taking the rifle apart. Always recheck your POI after doing any work on any rifle.
This kinda like Paul Harvey and now the rest of the story. Rifles are like fine wine and beautiful women every day they change just a little and you must keep up with those changes.
Tasco scopes are from the best but in this case I would bet your rifle being taken apart and put back together is the reason for the POI change. Before the hunt adjust the POI where you want it and leave it alone until the hunt is over. Check POI when you get to camp and you should have no trouble finding the kill zone.
 
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<Don Krakenberger>
posted
Took my BAR 30-06 out of the gun safe and checked it for wis whitetail season. It was dialed in 2 yrs ago perfect. I was 1.5 ft high and left of my target---couldn't figure it out---NOW THANKS TO YOUR GUYS I HAVE THE ANSWER--now i remember I took off my forarm and cleaned up the sliding mechanism 2 yrs ago after the hunt!!!---Thanks for "jogging" my memory. I gotta quit drinking beer!
 
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<Link>
posted
Hi I am no expert on guns. However when I assemble anything I try to go with a recommended torque. I use a inch of ft. lb. # torque wrench. This goes for the assembly of my guns also. Can't hurt? lol Don
 
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<TomJ>
posted
Was the bore clean? I noticed with my 30-06 that the first shot from a cold, clean bore was a little high and right.
I'd check the scope too. After 20 years experience, I no longer put any faith in Tasco, Simmons, Bushnells or other inexpensive scopes. Heck, you can buy a Leupold VariX II 3x9 for $180 at the discount stores now or a Nikon 3x9 for about the same money.
 
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