7mmmountaineer
Member
Time to face it I am a workaholic............
Posts: 521 
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Post by 7mmmountaineer on May 4, 2015 15:43:29 GMT -5
I finally got a chance to go shoot yesterday for the first time in over a month. I have been working with a friend off and on for the last couple weeks for a 7RM heavy bullet deer and black bear load for here local. He told me something I never would have believed if I hadn't seen it my self. The load is a pretty standard load for me 160gr Speer BTSP and Retumbo love the combo. He told me when he zeroed his rifle at 100yds it was over a foot high at 200yds and spot on at 250yds. I called bull$hit right away their was no way and it didn't make sense to me at all. So I met him at his place yesterday with my 7RM and the same bullet and powder and primer combo as his rifle. First he shot and sure as hell he wasn't even close at 200 almost 14 inches high. The I shot and despite shooting nickel sized groups at 100yds with this combo I too was high at 200yds not quite as high as he was 3 inches. Like he said he was spot on at 250yds but at 300 he was a foot low yet I was low at both 250 and 300yds. So my question is what could cause this. I checked my scope rings, bases, and even my parallax and my rig seems sound same for his. When we zeroed his rifle for 200yds he was low at 100 and 300yds. I am looking for some advice fellas I have never had his happen before and know of no one that ever had either.
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bob
Member
I'm too old to be nice but never too old to learn!
Posts: 1,457
Location: Northern California
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Post by bob on May 4, 2015 18:41:44 GMT -5
You're shooting in an area with a gravitational anomaly or a sever updraft.  Seriously though what is your muzzle velocity,I just want it for reference. Have you tried this with another brand bullet it just may be an introduced yaw of some sort. At any rate I've never encountered anything like that but now I will have to look for it. |
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Post by hacker54 on May 4, 2015 23:16:54 GMT -5
There could be several factors at play here. Weather conditions on that shoot as compared to other shoots. Barrel harmonics could be one as to how you hold and shoot from a rest compared to how your friend holds and shoots from a rest. Not all loads will shoot the same in different guns. My pet load for my 7-08 as per my post from the old house was great but might not shoot as well in another rifle in same caliber and model.
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7mmmountaineer
Member
Time to face it I am a workaholic............
Posts: 521
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Post by 7mmmountaineer on May 5, 2015 6:22:53 GMT -5
Ok Bob my velocity on Sunday I am not sure but when I worked this load up it was 3012FPS. It was also about 30-35 degrees cooler than it was the other day. I think that and the difference in altitude was 2000ft higher than normal might explain some of my POI differences. But not for the other rifle 14 inches high to spot on at 250 makes no sense at all to me.
Gary true what works well in one rifle doesn't always work well in a different rifle. This load was worked up in that rifle and until Saturday according to my buddy was shooting fine. In his rifle the load was most accurate according to him at 67.2gr. |
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7mmmountaineer
Member
Time to face it I am a workaholic............
Posts: 521
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Post by 7mmmountaineer on May 11, 2015 21:06:29 GMT -5
Ok so this has been eating at me so I returned to the scene of this puzzlement yesterday afternoon. Since it is finally drying out here I did a nice long walk around the area we were shooting in. I found 2 things right off the bat that I was not aware of the other day. First what I thought was a shallow running creek wasn't it's actually a cut creek and with the water being down it's close to 35 feet deep and 25 feet wide. Second the 200yd target was set up with in about 20 yards of this creek making an almost 90 degree turn. Even with the creek down to near normal levels their is still a pretty good up draft to shoot through. Now add an additional 15ft of water of fast moving water and if I thought this out correctly you would increase the amount of up draft NO? ?
Oh and my friend wasn't shoot a 160gr bullet either he was shooting a 140gr SIE PH. |
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bob
Member
I'm too old to be nice but never too old to learn!
Posts: 1,457
Location: Northern California
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Post by bob on May 11, 2015 21:19:49 GMT -5
Sever up draft! I really didn't think there was a gravitational anomaly!  In the words of Sgt. Schultz "very interestnik" . Glad you got to figger it out 'cause I couldn't for the life of me! |
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Post by hacker54 on May 11, 2015 23:01:47 GMT -5
I could see how that would effect bullet path down range just as a side wind would.
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Seriously though what is your muzzle velocity,I just want it for reference. Have you tried this with another brand bullet it just may be an introduced yaw of some sort. At any rate I've never encountered anything like that but now I will have to look for it.
In the words of Sgt. Schultz "very interestnik" . Glad you got to figger it out 'cause I couldn't for the life of me!
My daughter came from Missouri, my son and grand son, my wife and I had a nice dinner of grilled "porter house" pork chops, corn on the cobb, my son, G'son and I share 10/5. G'son is 4 minutes early though @ 10/4.
Pooh I hope you find to right house . 
