What causes horizontal stringing?


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mugsie
July 24, 2008, 07:53 AM
I was at the range the other day working up a new load for my 223 bolt action. I'm settling on 25 point something grains of Varget under a 69g HPBT. The load shoots nicely between 25 and 25.5, however at 25.5 I'm seeing horizontal stringing. I don't know if this was me because I was getting tired and at the end of the night, or something else at work here. What say the masters?

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JWarren
July 24, 2008, 08:55 AM
Not much of a master here, but the conventional reasoning has been that the barrel is warping due to heat build up and/or pressures being applied to the barrel over that heating period.

This is one reason many opt for heavy barrels, fluted barrels, and free-floated barrels.

Heavy Barrels are thought to be less prone to warping due to heat build-up and because they have more mass, they heat up more slowly.

Fluted Barrels are supposed to dissipate heat faster. It also supposedly increased barrel rigidity-- although this has essentially been debunked.

Many people swear by the benefits of fluted barrels, some not so much. Some just think they look cool. I like mine.

Free floating attempts to eliminate ANY pressures on the barrel from the stock, etc. This will allow the barrel to have no external pressure on it that will affect Point of Impact over the heating period. It should be noted that some rifles prefer some contact with the forearm and free-floating is not preferred to them. For those, it will be better to either bed the action or at least bed the barrel end of the stock.

It really depends on the rifle.

Again, I am no expert on the subject.


-- John

taliv
July 24, 2008, 10:02 AM
i'd say, 90% chance it's your position
10% chance, google "optimal charge weight"

dakotasin
July 24, 2008, 10:09 AM
assuming everything else is good (floated barrel, good scope, solid mounts, no undue pressure from the rest, etc) i have found horizontal stringing to be indicative of less than perfect bedding, and vertical stringing to be indicative of powder charge (ie need more or less powder - usually more).

everallm
July 24, 2008, 10:48 AM
If it was vertical stringing, my first thought would have been breath control second inconsistent powder metering

Horizontal suddenly popping up when you go to a hotter/faster load....

What's your barrel twist, if it's less than 1:9 that MAY be the issue with a heavy round

Stump Water
July 24, 2008, 11:22 AM
What's your barrel twist, if it's less than 1:9 that MAY be the issue with a heavy round

+1

Most of your garden variety .223 bolt actions won't have a twist rate that will stabilize a 69gr. bullet.

SlamFire1
July 24, 2008, 12:17 PM
i'd say, 90% chance it's your position

At least.

Stock weld is just as important for scopes as it is for irons. I regularly shoot irons in Highpower competition. Also in small bore. Just moving that face up and down the stock will move the point of impact from 12 OC to 6 OC. I believe I saw the same effects prone with a precision scoped rifle at 200 yards. Moving the buttplate left and right on the shoulder will move the point of impact left and right.

When your position changes each and every shot, your errors are a combination of up and down, left and right, and will totally confuse you.

Wrap your thumb across the stock, and put your face on it. Or nose. Do it consistently. Place that buttplate in the same spot at the same altitude on your shoulder. Be conscious of your position. It makes a difference in point of impact.

mugsie
July 24, 2008, 12:55 PM
In answer to a few of the questions posed above - it's a Savage model 12, fluted bull barrel, 1:9 twist. It stabilizes 69g very well. Working up from 24g's, my groups were within 1 moa but just barely (sorry I don't have pics of the target but I'm at work). At 24.5 they tightened up a bit, 25 had 2 shots through 1 hole, 2 shots through another hold about 1/4 to 1/2 inch away, and 1 shot by itself, but within 1 inch of the first group. In effect, these were all within 1 moa with a couple through the same ragged hole. At 25.5 they were exactly hohizontal and each almost 1/8 inch from it's buddy, almost like I was trying to stitch a perfect line.

The rifle was on a wooden rest with a piece of carpet over it, stock resting on the carpet. Barrel is free floating. Butt plate was against my shoulder. Granted I was getting anxious as I closed in on the group and my heart rate was climbing, but I would think this would give sorta circular groups, not perfect horizontal stringing. I was waiting about a minute or so between shots. I tend to think it was me and 25.5 Varget over 69g HPBT is the way to go, but I'm curious about the stringing. I'll load some more at 25.5 and try them again and see what happens.

Any other suggestions or comments guys - and no, the rifle isn't broken and no, I'm not going to send it to anyone! :neener:

DoubleTapDrew
July 24, 2008, 01:21 PM
This is a good article of things to try: http://www.6mmbr.com/verticaltips.html

FEG
July 24, 2008, 03:55 PM
In my limited experience, powder position (low load density) causes vertical stringing. I am not in a position to figure the load density of Varget here, so I could be misguided.

Rifleman 173
July 26, 2008, 09:12 PM
You can get any sort of stringing because of the way a barrel heats up. Sometimes, as in the case of most Rugers, they will string vertically. In your case, your rifle as it gets warm strings horizontally. A really good rifle should not string at all. But that also has to do with the loads you shoot, the barrel's steel and so on. It is almost impossible to actually get a rifle that does not string if even just a tiny little bit.

homers
July 26, 2008, 10:00 PM
cross wind?

rangerruck
July 26, 2008, 10:18 PM
the problem is simple; the bbl, is touching the stock. Easy way to check is two ways; next time out at the range, shoot a round, and wait at least 1 full minute, between shots, that is, 1 minute before you even begin to settle in for the next shot. if no stringing occurs, then I am right. Another way to check is to heat her up. let 10 or 20 shots go, but before you do, check the freefloat, with a dollar bill , or a piece of paper. Also bring a pencil, and make marks on the bbl, to show any sticking points, make your marks right on the bbl.
Then heat it way up, shooting a bunch of rounds, and get that bbl cooking.
Now recheck the freefloat, and make marks again , on the bbl.
If your sticking points now exist, are have moved up or down the bbl, I am right again. This is especially true if the stringing is occurring allways in the same direction.

kennedy
July 26, 2008, 10:41 PM
when i have horizonal stringing its because my body is wobbling side to side. when that happens i put my rifle away and shoot my hand guns.

Cypress
July 26, 2008, 11:06 PM
I have this problem when shooting my .223. I have found that I cant the rifle a little after I have shot quite a bit.

Matt304
July 26, 2008, 11:11 PM
Homers:

cross wind?

I can't believe it took 11 posts. :D

First of all, we are arriving at all of these conclusions, and we know very little about Mugsie's details.

Was there any crosswind, and how much? 5-10MPH crosswind equates to 0.5-1.0" drift on your load at 100 yards. I'd say if you even had noticeable 5-6mph breezes, that is definitely enough to get the horizontal stringing you speak of on your group size. And, it is probably the most likely cause if the wind came up while shooting. Or, it could have been there the entire time, and if your position finally steadied up to where you actually held better vertically, you will then begin noticing the horizontal line from the variable wind involved.

When groups are only hovering at 1MOA to begin, it can be tough to figure out what is going on without shooting a lot of targets for consistency. It sounds like there is not enough shooting or tight groups involved to reach any solid conclusions here. I would say, keep shooting, and report back.

bogie
July 27, 2008, 04:48 AM
Horizontal?

Wind, bench moving (they sometimes do... look through the scope, and whack the bench or lean on it...), wind, shoulder mirage, wind, trigger, wind, loose nut behind the buttplate, wind, loose rest, wind, bag moving, wind, trying to shoot with a bipod, wind, or, maybe, wind.

mugsie
July 27, 2008, 11:24 AM
Resolved!

I was going crazy trying to figure this out, but I think I've got it since the other day I shot 5 rounds virtually touching in a nice little group. Did it again the following nite on several occasions and can do it again and again almost to the point of boring.

1) I was timing my heart rate and watching it in my scope. If I fired between beats, the shots grouped very nicely.
2) I was watching the wind conditions - strung some little pieces of flimsy material down range and shot when it was calm.
3) waited slightly longer between shots - not so much because of the barrel cooling (it's a bull barrel and slightly fluted) but more to calm myself down - sorta get into the zen zone.

Maybe one of these is more important than the others, maybe in combination they're all important, but putting consistantly, 5 rounds inside a dime at 100 yards, is one great feeling.

I thank all of you for responding and trying to help. Thanks.

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