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I see this quite often in different rifles/different loads.
I rule out loose screws, bad scope, hold, etc.
I support all rifles at the bench on the forearm, gentle squeeze, etc.
It just seems to come up infrequently, drives me nuts.
I sort all brass by OAL to the thousandth, all bullets to the 1/10 gr, primers from same box, mix up powder prior to measuring/pooring, then shoot a group of 4 with all these matched components.
Any ideas (too slow, too fast?)

Tracy in IL
 

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Does this tend to happen at 100 yards, 200, 600? After 2 up, 2 down, do the following groups pattern more or less normally?

Based on your comments, you seem to know what most of the common causes might be and you check for them. About the only thing you didn't mention is wind flags. Can you tell us distance and tell us whether you use flags, what type, and how many. Brief, strong gusts from 12 o'clock or 6 o'clock can fairly easily cause what you're experiencing, and without flags, you may never realize what's going on.
 

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Vertical shot disbursement, where bullets pairs up to create their own groups, so to speak.
There is a variety of elements that will cause squirrely barrel harmonics....Free floated barrels,
especially light sport weight, that allow unimpeded tones and overtones of the vibrations vs controlled
harmonics, such as bedding for adjustable forearm pressure. To crowning the muzzle with a piloted tool.

I once had a 243 that did vertical strings of around 3 inches....I added a lit'l forearm pressure and the rifle then with the same
loading put four outta five that could be covered by a dine and all five, a nickel would cover 'em at a 100 yards off of the bench.

My pre64 300 Win Mag. is a moa rifle....One morning at the range, it would not group a proven load at all. Checked
stock screws, checked scope mounting, etc... Nothing loose, not one thing amiss. I glanced at the box of fired cartridges
the firing pin strikes were off center, some primes hits off center by a lot. Jerked the bolt out, and sure enough the firing pin
hole had broken out, allowing the pin to strike the primer along the anvil leg or between them for erratic ignition.
Bushin'd the bolt face and all was back to an inch or less at a hundred yards.

If a clean bore shoots a couple high, low or off the point of aim, then will group subsequent rounds to a satisfactory level...
It sounds like a cold shot conundrum or the bore just needs a lit'l jacket material to fill the voids.

From Shilen Rifle, Inc Welcome to Shilen Rifles, Inc. FAQ
How clean is clean?
We get this question many times and have a great deal of difficulty helping some customers understand that a rifle barrel does not have to be spotless to shoot great. Many times more harm than good is done in trying to get it that way. Picture a car's fender. If the fender has a small dent in it, then professional application of body putty fills the dent. When painted over, the dent becomes unnoticeable, and the surface of the fender is smooth and consistent. The same thing happens in a rifle barrel on a microscopic level. Removing this small trace of copper puts you right back to square one. The next bullet that crosses that area will, again, leave a small trace of copper. Similar to patching a pothole. All successful benchrest shooters shoot one or more "fouler" shots down the barrel before going to the record target. This is not to warm up the barrel. They are resurfacing it on the inside. Benchrest shooters clean between relays to get the powder fowling out, not the copper. However, since copper usually comes out with the powder, they know that it must be replaced to get "back in the groove". I've had shooters tell me they "cleaned their rifle for 3 hours to get all the copper out of it." Their next statement is almost invariably that they had to shoot 4-5 rounds through it just to get it back to "shooting" again. This tells me that in order for the rifle to shoot well again, they had to replace the copper they worked so diligently to remove. I have a 7x08 Improved that shoots the same 1/2" MOA after 15 minutes of cleaning or 3 hours of scrubbing and de-coppering. Personally, I prefer shooting to cleaning. The gist of this is to set a regular cleaning regimen and stay with it. If the accuracy of the rifle is acceptable with a 15 min. cleaning, why clean longer? I would much rather have people admiring the groups I shot than marveling at how clean my barrel looks on the inside.
 

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Rushin4, it would help with a bit more info . What is your rifle. Factory or custom barrel. Is it bedded and if, by what method. A few ideas on your loading. Cases should be trimmed not sorted to the same length it's actually a safety issue. Never heard of mixing your powder before pouring, it's not helping or hurting, but wasted effort. Weight sorting bullets unless your shooting some real junkers is useless. Shooting primers from the same box if your buying same brand and number is pretty useless also. My ideas come from years of both short and long range benches competition at the highest levels and trying things, not just latching on to what I read or heard someone say. Another thing t.o know, your 2 and 1 groups, are they smaller that a dime, bigger than a quarter , and at what distance. With some more info we can help I think.
 

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I see this quite often in different rifles/different loads.
I rule out loose screws, bad scope, hold, etc.
I support all rifles at the bench on the forearm, gentle squeeze, etc.
It just seems to come up infrequently, drives me nuts.
I sort all brass by OAL to the thousandth, all bullets to the 1/10 gr, primers from same box, mix up powder prior to measuring/pooring, then shoot a group of 4 with all these matched components.
Any ideas (too slow, too fast?)

Tracy in IL
What is the distance?
 

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Shoot a 22 RF. abit....... if same thing happens.... it`s the nut behind the bolt.....
caused by flinch.
if not....
parallax in scope......
magnified by inconsistent cheek weld and varied hold on gun....
let another person shoot your gun....



























inconsistent hold and cheekweld....
 

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Cures for Vertical Stringing


Speedy Gonzalez, noted shooter, gunsmith and recent inductee into the Benchrest Hall of Fame, offers these pearls of wisdom to help you eliminate vertical in your shot strings. Remember that vertical can result from myriad gear issues and gun-handling mistakes. Try to isolate one item at a time as you work to improve your groups.
MECHANICAL and HARDWARE ISSUES
• Barrel Weight–A lot of rifles are muzzle-heavy. Some rifles have too heavy a barrel and this causes vertical, especially when shooting free recoil. Basically the gun wants to tip forward. The remedy is to trim or flute the barrel, or add weight in the rear (if you can stay within weight limits).
• Unbalanced Rifle–If the rifle is not balanced, it does not recoil straight, and it will jump in the bags. If the rifle is built properly this will not happen. Clay Spencer calls this “recoil balancing”, and he uses dual scales (front and rear) to ensure the rifle recoils properly.
• Firing Pin–A number of firing-pin issues can cause vertical. First, a firing pin spring that is either too weak or too strong will induce vertical problems. If you think this is the problem change springs and see what happens. Second, a firing pin that is not seated correctly in the bolt (in the cocked position) will cause poor ignition. Take the bolt out of rifle and look in the firing pin hole. If you cannot see the entire end of firing pin it has come out of the hole. Lastly, a firing pin dragging in bolt or shroud can cause vertical. Listen to the sound when you dry fire. If you don’t hear the same sound each shot, something is wrong.
• Trigger–A trigger sear with excessive spring load can cause problems. To diagnose, with an UNLOADED gun, hold the trigger in firing position and push down on sear with your thumb. If it is hard to push down, this will cause vertical problems.
• Stock Flex–Some stocks are very flexible. This can cause vertical. There are ways to stiffen stocks, but sometimes replacement is the best answer.
• Reliability–ALL your bench equipment must work flawlessly. If it doesn’t, get it fixed or get rid of it. We need all our attention on wind flags.
 
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