Temperature and loads...


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Afy
November 30, 2008, 08:23 PM
Well yestterday was relatively cold in France.
3 degrees Centigrade.

My pet load of 41.7 grains of N550 under a 139 gr Lapua Scenar normally gives me about >0.5 inch 5 shot groups at 100 meters.

What I saw was vertical stringing with a normal grip. And horizontal with free recoil.

What is happening? Is it temperature? Should I up or lower??

Much appreciated.

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Walkalong
November 30, 2008, 08:28 PM
When I got vertical stringing with a known good load, I always looked at me first. Did it do it consistently? If so, and you ruled you out, it may need a little bump, if you have room to bump.

I was shooting next to a very good shooter one day at Riverbend. He was just a fussing. Blamed his brass. He chucked it in the trash. I got it out, loaded it, and beat him with his own brass the next group. Then he got so mad he screwed his barrel off and changed it. Moral is, sometimes we just have a bad day. I know I have. At the time, he was a better shooter than I was, he was just having a bad day and blaming it on equipment instead of himself. I always looked at me first when groups went South.

jcwit
November 30, 2008, 10:22 PM
If a person is diabetic really look out. Your eyes screw around with you depending where your blood sugar is at.

Ridgerunner665
November 30, 2008, 10:24 PM
Sounds like it could be your rifle instead of the loads...

Is it a wood stock?

Afy
December 2, 2008, 12:42 PM
not a wood stock, not diabetic, and yes there is a little room to bump.

NCsmitty
December 2, 2008, 07:55 PM
Afy, it sounds like a bedding problem. Is the barrel bedded or floating? Have you checked the action screws for proper tension. I really do not think your loads are the problem with the reaction that you experienced in stringing both ways. VV powders, from what I have researched, are fairly temperature stable in their 500 series powders, and less so with the 100 series.
Look to the gun and/or your shooting platform for rectifying the problem. Things can change when you're dealing with near freezing temps. Did the stringing occur right off or after the barrel heated up?

NCsmitty

Afy
December 3, 2008, 02:44 AM
NC Barrel never did heat up. Way too cold for that. Just mildly warmed up. Stringing occurred on the second and thrid set of groups.

First 5 shots were taken at randomly for fouling. about 5-10 minutes between groups. Rate of fire was approximately 1 shot every 30-45 seconds.

The barrell is fully free floated, and the rifle is aluminium bedded.

Will check all the nuts, especially the one behind the rifle.

Ridgerunner665
December 3, 2008, 02:47 AM
Yep...I was leading up the same idea that NCsmitty has...

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