Spike Camp

Sand bag placement for accuracy test

Sand bag placement for accuracy test
« on: May 16, 2018, 08:29:40 AM »
Has anyone noticed a difference in accuracy dependent upon what part of the forend contacts the front rest or sandbag? For example, at the end, middle or close to the trigger guard.
Is there  best practice or just see what the gun likes? It always seemed the gun shoots slightly high when the sandbag is at the end of the forend.

Re: Sand bag placement for accuracy test
« Reply #1 on: May 16, 2018, 09:42:51 AM »
Sounds like you're getting a pressure point on the barrel from the placement of the sandbag. The "paper test" that we often do to check if a barrel is free floated isn't really a good test because that's not much space at all. If that's all the clearance the barrel has, the stock can easily move that far, contact the barrel, and change your point of impact.

I'd check the clearance of your barrel with the sandbag in different locations. Depending on what type of stock you have, glass bedding can be added for rigidity, or material can be removed to ensure proper clearance. Of course Weatherby may not like this should you ever need to send the rifle back for any issues...
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.257

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Re: Sand bag placement for accuracy test
« Reply #2 on: May 16, 2018, 10:00:22 AM »
Many variables here
#3 contour barrel correctly free floated should not be affected by the sand bag at the end of the stock
#1 barrel with a pressure point with the sand bag under the end of the stock and a warm barrel could affect point of impact.
Also as noted by Cbloom20 incorrect free floating can affect point of impact
Also type of stock, how much flex does it have

This has to be assessed per gun
Mike

Re: Sand bag placement for accuracy test
« Reply #3 on: May 16, 2018, 11:45:37 AM »
That makes sense and thanks. This is a model 700, pillar bedded with wood stock, sporter barrel. Sandbag under the single pressure point raises POI about 1 inch at 100. When I break in the Weathermark I will pay attention to sandbag placement to help insure consistency.

dubyam

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Re: Sand bag placement for accuracy test
« Reply #4 on: May 17, 2018, 09:24:37 AM »
I've found most synthetic "tupperware" stocks and some wood stocks have too much give in the forend, and end up creating upward pressure on the barrel if rested out near the tip.  To combat this, when I do load development, I use the front trigger guard screw as my rest point, or as close to that as I can get.
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Re: Sand bag placement for accuracy test
« Reply #5 on: May 17, 2018, 06:49:26 PM »
That makes sense and thanks. This is a model 700, pillar bedded with wood stock, sporter barrel.

An option is to have a smith remove material frm the barrel channel, and add glass bedding to increase rigidity.
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Stacy

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Re: Sand bag placement for accuracy test
« Reply #6 on: May 18, 2018, 08:26:19 PM »
I find it best to hold the forend of the rifle too even off the bench. I didn't catch if you were holding the forend or not so I'm mentioning it. 

Re: Sand bag placement for accuracy test
« Reply #7 on: May 18, 2018, 09:41:35 PM »
I  like Dunyams suggestion of  resting the gun on the front stock screw. It's easily repeatable.
Stacey also has a good point about holding the forwnd. My experience is that improves accuracy. But not sure why.
I plan to be more methodical with the new gun and use consistent approach. Thanks guys.

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Re: Sand bag placement for accuracy test
« Reply #8 on: May 19, 2018, 06:09:05 AM »
If you plan on using a tri-pod hunting, either use it also at the bench or at least place the sand bag under your sling stud
Mike

Re: Sand bag placement for accuracy test
« Reply #9 on: May 20, 2018, 05:01:49 AM »
Yep. Another good point. Practice what will occur in the field.