Need a little advise from the pros..ok here's the deal.i got a new 338 edge shooting 300g sierras and did some testing. Groups at 350 yds show 1/8" vertical group but a 1 3/4 horizontal group. The wind was calm under 3 mph probably more like 1 mph. Shooting is done off a bipod and rear sand bag. Could this be a shouldering problem with this cannon or is something else to blame. I am familiar with shooting larger guns, but spend most of my time shooting a 6br for groups ,not a 338 edge .maybe I just need to change my technique for this monster. Thanks For any info K Redden
Poor horizontal grouping
- Thread starter K redden
- Start date
Alex Wheeler
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Adjust your seating depth.
Thank you Malibu you seem to always have an answer for my questions . At the moment it is .065 jumped . I thought it would be a bit far ,but the first loads produced such good vert. I hadn't adjusted the depth yet . I'll probably seat them out in increments of .015 until I find something close ,then go from there.
Ditch the bipod for a solid front rest [ http://bulletin.accurateshooter.com/wp-content/uploads/2010/12/lohbig03.jpg ] and a cement bench [with a 400lb top or there abouts] for testing. A .001" movement at the bench usually equates to 1/4" movement on target at 100 yards. Use wind flags even in conditions that appear to be calm. A lot of bullet movement can take place over 350 yards. 
Got this from my friend Gene. See if this helps.
TUNING OUT HORIZONTAL & VERTICAL DISPERSION
Most of my shooting during the past several years has been in the wind free environment of the tunnel. One thing that continues to repeat with every gun, barrel and bullet combination I have worked with is that
horizontal dispersion results from bullets being seated too far into the lands
vertical dispersion is the result of the powder charge being either too hot or too light.
Daryl Loker told me years ago that you tune out horizontal with neck tension and bullet seating depth,
tune the vertical out with the load. (Or in recent years since the advent of tuners, with the tuner.)
I assure you, if I put my standard load of powder in and seat the bullets on hard jam, I'll have two bullet holes of built in horizontal, and that's in a tunnel with no wind!
Pushing bullets back into the case .005 at a time, and the horizontal will disappear just when the bullets come off the lands or just kissing.
You might as well keep this to yourself after you see it with your own eyes because no one will believe you if you try to tell them; it goes completely against conventional wisdom.
Gene Beggs
TUNING OUT HORIZONTAL & VERTICAL DISPERSION
Most of my shooting during the past several years has been in the wind free environment of the tunnel. One thing that continues to repeat with every gun, barrel and bullet combination I have worked with is that
horizontal dispersion results from bullets being seated too far into the lands
vertical dispersion is the result of the powder charge being either too hot or too light.
Daryl Loker told me years ago that you tune out horizontal with neck tension and bullet seating depth,
tune the vertical out with the load. (Or in recent years since the advent of tuners, with the tuner.)
I assure you, if I put my standard load of powder in and seat the bullets on hard jam, I'll have two bullet holes of built in horizontal, and that's in a tunnel with no wind!
Pushing bullets back into the case .005 at a time, and the horizontal will disappear just when the bullets come off the lands or just kissing.
You might as well keep this to yourself after you see it with your own eyes because no one will believe you if you try to tell them; it goes completely against conventional wisdom.
Gene Beggs
Once you get through trying all the great suggestions here that are within your control, another possibility is excessive inletting tolerances around the action. You have not mentioned if this is a custom rifle with a professional bedding job. If you shoot 6 br for groups, you are most likely used to shooting a gun with tight tolerances and very little/no slop. The heavy recoil of your .338 will exacerbate your problem. Often, having the bedding professionally done will solve this problem.
As a proof source Alex Sitman of Masterclass stocks says: "These tolerances usually occur around the recoil lug and here is where down range accuracy comes in. Rifles were the lug is left "loose" in the bedding have a greater chance of giving the shooter horizontal stringing from the torque put on the action upon firing. For this reason and the fact that the stock isn’t mated properly to the action, the stock should be at least surfaced bedded to snug up these areas. Properly done, accuracy should be increased."
This may be your issue. As a group shooter, I doubt it is your technique but you never know.
As a proof source Alex Sitman of Masterclass stocks says: "These tolerances usually occur around the recoil lug and here is where down range accuracy comes in. Rifles were the lug is left "loose" in the bedding have a greater chance of giving the shooter horizontal stringing from the torque put on the action upon firing. For this reason and the fact that the stock isn’t mated properly to the action, the stock should be at least surfaced bedded to snug up these areas. Properly done, accuracy should be increased."
This may be your issue. As a group shooter, I doubt it is your technique but you never know.
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