What causes vertical stringing?

Paul in Idaho

Well-known member
Joined
Aug 9, 2012
Messages
829
Location
Southwest Idaho
I just saw Laelkhunter's post on this topic and remembered I have been meaning to ask about the problem of vertical string results in my own shooting.

In most of my practice at the range, I have seen vertical stringing in my hunting load. I haven't been able to figure out if it's something I'm doing, or if it's an issue with the load. So far I only use factory-loaded ammunition. There isn't a consistent progression - sometimes the first shot is high and later shots string lower. Other times the first shot is lowest and others go higher. The horizontal variance is minimal.

Can you experts help me figure out what might be happening?
 
Seating depth or bedding problem. As elk magnet said, it could be a parallax issue. What kind of scope are you using?
 
One thing that I have found with my own shooting, is that I tend to change my rifle hold too often. It WILL change your impact point. I have to really concentrate, when I am on the bench. I don't seem to have problems in the field, as it is a more natural hold, than what I get on the bench. I guess that I have less time to worry about it in the field.
 
I had always thought the vertical stringing was caused by improper bedding of the barrel (contact somewhere) or a free floating barrel having contact somewhere in the barrel channel. As the barrel heated up, it could cause the vertical stringing if there was contact. In my case however, I only experienced the vertical stringing (a three inch group) with one powder, RL22. The 4350 and the RL19 produced a cluster of shots around an inch or less.
In your case, it might be loose action screws or barrel contact with the stock. After making sure the action screws are tight, try sliding a piece of paper between the barrel and stock, and see if it slides from the chamber to the end of the stock without binding. If it catches somewhere, you have contact between the barrel and stock.
 
As others have said, it could be a bedding issue; something mechanical. Case in point: I bought a Remington Model 600 in 350 Remington Magnum from a shop in Kalispell Montana on Gun Broker. The rifle is circa 1966 or so and had a plastic vent rib that serves no functional purpose. It came with the original rib and a replacement aluminum rib mounted on it, and the original plastic trigger guard unit (that always warp over time) had been replaced with a new metal one.

Upon shooting, the first shot would hit about 2" high where I had sighted it. The next would be 3" high, the third would be about 4" high. I killed deer with it, but never had to shoot more than once.

I tried free floating the barrel, didn't make a difference. I pondered having it glass bedded or pillar bedded at a gunsmith. So somehow, I came up with the notion to put the original plastic rib back on. I hit paydirt! The metal rib was somehow applying a slight upward force on the barrel as the barrel heated up from repeated shots. The gun now shoots a 1.5" group with handloads and no longer exhibits the vertical stringing that once plagued it.
 
As others have said, it could be a bedding issue; something mechanical. Case in point: I bought a Remington Model 600 in 350 Remington Magnum from a shop in Kalispell Montana on Gun Broker. The rifle is circa 1966 or so and had a plastic vent rib that serves no functional purpose. It came with the original rib and a replacement aluminum rib mounted on it, and the original plastic trigger guard unit (that always warp over time) had been replaced with a new metal one.

Upon shooting, the first shot would hit about 2" high where I had sighted it. The next would be 3" high, the third would be about 4" high. I killed deer with it, but never had to shoot more than once.

I tried free floating the barrel, didn't make a difference. I pondered having it glass bedded or pillar bedded at a gunsmith. So somehow, I came up with the notion to put the original plastic rib back on. I hit paydirt! The metal rib was somehow applying a slight upward force on the barrel as the barrel heated up from repeated shots. The gun now shoots a 1.5" group with handloads and no longer exhibits the vertical stringing that once plagued it.

I wonder what it would do if you left the rib off completely? Wouldn't look as nice, but might be a sub-moa rifle.
 
Had another thought. DON'T leave a live round in the chamber of a hot gun for long enough to heat the powder up hotter than the other rounds. Some powders are temp sensitive
 
Yeti GOBOX Collection

Forum statistics

Threads
110,807
Messages
1,935,175
Members
34,887
Latest member
Uncle_Danno
Back
Top