vertical stringing


October 22, 2008, 07:40 AM
Could someone please explain vertical stringing and what causes it? I have seen it referenced in posts and in articles I was reading from a accuracy magazine I was recently reading.

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October 22, 2008, 07:52 AM
It's when the dispersion of your shots is primarily up and down. For example, in a 10 shot group, if the spacing of your two widest shots on a horizontal plane are 4", while the spacing of your two widest shots on a vertical plane are 10", that is indicative of vertical stringing.


October 22, 2008, 07:55 AM
Breathing will cause vertical stringing.

October 22, 2008, 08:20 AM
Poor shoulder control (inconsistent) will cause vertical stringing. Really bad ES's will cause it at longer range.

October 22, 2008, 08:46 AM
Failure to maintain the same focus on the front sight and sight picture with respect to the target will cause it also.

October 22, 2008, 08:47 AM
Poor breath control is a regular culprit as well as, at long range, inconsistent powder throw in hand loads.

October 22, 2008, 09:43 AM
Seems like most of the culprit is in shooting technique, rather than handloading mistakes.

I have a 3 shot group which is a tight 0.6". They are .223 55gr fmjbt fired from an AR at 100 yds (I believe I can still improve this by modifying seating depth). The holes are basically touching but in a vetical line. Is this vertical stringing? Or does there have to be some spread for vertical stringing?

October 22, 2008, 09:56 AM
Vertical stringing with a bolt action especially, quite often occurs as the barrel heats from repeated shots. Often if a barrel has contact with the forward portion of the stock, the heating will cause the shots to rise progressively.
I float all my bolt rifle barrels.


The Bushmaster
October 22, 2008, 11:29 AM
My Browning A-bolt barrel has been floated and I have a vertical stringing spread of three shot 1 5/8" at 200 yards. Guess it's my breathing...

October 22, 2008, 11:57 AM
A single 3-shot group tells you NOTHING.

The Bushmaster
October 22, 2008, 02:12 PM
L O L...:D Guess I should have put a "big Grin" smilely on that one...

October 22, 2008, 02:21 PM
How dare you shoot three-shot groups! :cuss:

Don't you know that anything less then 20 10-shot groups is statistically insignificant!

If you don't burn out a barrel during load development, you just aren't going to be statistically significant! :D


October 22, 2008, 02:51 PM
I agree. If I can't produce a clinically significant sample every time I fire I should just keep the guns locked away and not even bother to go to the range???????

come one guys

Life dictates that sometimes you do things in a less than ideal manner. At that point in time I had a time limit.

I understand that none of you like 3 shot strings but this question was designed to help me learn something about vertical stringing, not 3 shot, 5 shot, 10 shot, 20 shot, or 100 shot groups.

By the way. To the question of statistical significance, a power analysis dictates that you will need far more than 10 shots per powder weight change if you select 4 different powder weights.

October 22, 2008, 02:57 PM

The Bushmaster
October 22, 2008, 04:38 PM
I don't know swampshooter. When I add them all together (several 3 shot strings[groups]) they tell ME a lot...:scrutiny:

Yes...I know...rcmodel...I did a cardinal sin...:D

October 22, 2008, 07:53 PM
A single 3-shot group tells you NOTHING.It can show potential, that is for sure. If you get real serious, you can jump up to 5 shot groups.

For a hunting rifle 5 shot groups are overkill by 3 shots, maybe 4.

If your hunting rifle will shoot a good 3 shot group over and over, you've got a good one.

There is no reason not to let the barrel cool between shots either, unless your testing a target rifle that may have to shoot a lot of shots in a hurry.

October 22, 2008, 08:03 PM
alot of times when i am coaching soliders an people in general i see the "stringing" when they change thier point of aim from shot to shot. i hope that we are discribing the same thing here but i think we are.

Ky Larry
October 22, 2008, 09:16 PM
As was stated above, vertical stringing can be caused by the barrel heating and making contact with the stock. Itcan also occur in a rifle that has a freefloated barrel. I had a Ruger 77 in .243. I freefloated the barrel but after 5 shots the barrel was making contact with the stock. A gunsmith told me this was caused by stress in the barrel due to uneven heat treating and tempering. The answer was to let the barrel cool after 4 shots and the stringing problem went away.

uk roe hunter
November 1, 2008, 06:11 PM
this problem may also be due to the stock bolts not being tight enough. the rifle action must be pulled down and bedded properly. I agree with the barrel floating theory. my rifle barrels all float except my model 7.

November 1, 2008, 07:30 PM
With my NRA "service rifles", I can clearly see vertical stringing in the prone position.

As your face slide up and down the stock, the point of impact on paper goes up and down. I think it goes, move up, the point of impact moves up.

People do not want to acknowledge that the greatest error source is the shooter, and the greatest source of shooter error is inconsistant position. Call it a poor "stock weld".

I saw this today shooting standing with my M1a. As I moved closer to the sight I had to add elevation. I shot a 95-2x standing. That was my best string, my position stunk today.

You notice vertical stringing when your groups go up and down, but not sideways. With a target rifle, it is easy to figure out that the cause is poor position.

When I have rifles that vertically strung, in all but one case, it has always been due to poor bedding. Seldom will poor bedding only show up in vertical stringing, you will also have variations side to side, but I think the biggest deviation is vertical.

I have one Ruger #1 in 30-06. It vertically strings everything in a perfect line. The line is about 2" high. I have played around with tension screws, free floating, pressure bedding. The thing vertically strings.

November 2, 2008, 12:19 AM
Well here's a different answer for you. Vertical string CAN be caused by using the wrong powder. Or a powder with the wrong burning rate for the cartridge being loaded.

I saw it happen once with my 7 X 30 Waters contender. I experimented with 4198 powder, even though there were no loads in any of the manuals for it. I understood exactly why that was, it is not suited for that cartridge! The group was a long, straight line of holes, like rungs on a ladder. 4895 turned out to be THE one powder that produced excellent round groups in that pistol.

November 2, 2008, 08:34 AM
Snuffy, you are right on! Not that anyone else is wrong. If stock weld is good (and we are talking bedded bolt rifles) I have noticed powder as the culpret, either poor choice or poor volume. I have found vert stringing to occour right around the "sweet spot" in load development, either a few tenths more or less powder will bring em back to round.

November 2, 2008, 10:26 AM
I shoot a Ruger #3 and a couple of Encore barrels.

By letting the brass stretch between the shoulder and the base and subsequently eliminating any headspace my single shots will vertically string reliably.

I was trimming the brass (necks) to the right case oal but not paying attention to the shoulder to base dimension. After I bumped the shoulder back I got the best shooting from the number 3 that I have ever experienced and my Encore barrels became more predictable.

November 2, 2008, 11:38 AM
Not that anyone else is wrong.

I didn't mean to imply the other answers were wrong, they ALL could certainly cause vertical stringing. I simply wanted to add the powder choice to the equation.

By letting the brass stretch between the shoulder and the base and subsequently eliminating any headspace my single shots will vertically string reliably.

Very interesting! I will keep that in mind when sizing for my contenders!

November 2, 2008, 02:05 PM
Get a Mini-14 and you will learn all you want about vertical stringing... :evil:

November 2, 2008, 02:54 PM
A single 3-shot group tells you NOTHING.

That read about a 9 on the old Tension scale, Mate.

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