Vertical Stringing

R

reynolds357

New member
I just bought a Savage 11 ultra lightweight that is vertical stringing. 2 inch vertical string at 100 yards. A five shot group will consistently start 2" high at 100 and move straight down a line and finish 2" below where the first shot was.
Its floated and I assume Savage pillar bedded it. My thoughts are barrel moving as heated, but from what I have read about this rifle the barrels are supposed to be top of the line barrels that have been completely stress relieved. I am considering glass bedding. Tried a few different loads. They all vertical string. Some more and some less, but they all vertical string. My best load vertical strings in a perfectly straight line. Tomorrow I am planning on playing with the torque on the stock bolts. If that does not work, I guess I will glass bed it tomorrow night. Anyone have any ideas to try first?
Tally ultra light base/rings combo. Bases bedded and rings lapped. The base and ring is one piece on front and one piece on back.
 
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While you are testing things at the range try a pressure pad at the end of the forestock. Cardstock or regular paper folded up makes a good test pad. Try various amounts of pressure. If that solves it make a permanent pad with epoxy.
 
Is the spread progressive or more random? What type of rest are you using?
Vertical stringing can be caused by nonuniform shoulder contact and varying recoil attenuation.
 
While you are testing things at the range try a pressure pad at the end of the forestock.
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All my older Remingtons had this feature, I don't know if Remington still does this or not.

However I have a Savage and Stevens, they don't have that feature and they don't vertical string.

Another thing that can cause vertical stringing is erratic ignition. If you are using handloads you might want to check your primer seating.

Best Regards
Bob Hunter
www.huntercustoms.com
 
First off, barrel dimensions have nothing to do with it's bending as it heats up. Skinny, whippy barrels will shoot just as accurate as fat, stiff ones starting cold and after 30 shots fired 20 seconds apart, still shoot extremely tiny groups. And a lot of those short, skinny sporter barrels are actually stiffer than longer, heavier ones. Good example's the original M14NM standard weight barrel; 'twould shoot inside 2/3 MOA at 600 yards shooting 25 to 30 shots in less than 22 minutes in a match. They's shoot the same in special rapid fire matches putting 24 shots down range to 600 yards in 50 seconds.

Any rifle that walks its shots as the barrel heats up does so for one or more of these reasons:

* barrel's fit to the receiver with hard contact at only one point around the barrel tenon shoulder; the receiver face ain't square with the tenon threads.

* barrel's got an epoxy pad under its chamber; as the barrel expands from heating up, more pressure's put on the barrel from underneath it and that alters how the barrel whips vertically when fired.

* barrel's not properly stress relieved or has poor metalurgy distribution in it (rarely happens).

* shooter holds the rifle differently each time it's shot as its fore end rests atop something; he keeps changing pressure against the stock in the same direction shot after shot after shot. Often happens with a pad under the barrel at the fore end's tip.
 
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Could be...that your stock bolts are not properly torqued. Bart can probably tell you which one gets tightened first. First thing...you have to make sure the barrel and receiver is properly seated into the stock. I think that you should first --- hold the barrel of the gun with the muzzle vertically straight up --- and tap the butt stock gently on a carpeted floor, to make sure the barrel and receiver is properly seated into the stock. I think you should call a qualified gunsmith, as to which stock bolt gets tightened first.

With my faint recollection....the stock reciever bolt gets tightened first, then the forearm bolt. Go back to the receiver bolt for the final torque --- then the forearm bolt. Could be that that your stock bolts are too long.
 
Everyone, thanks for the help. I just diagnosed the problem. I went back to the range and the vertical stringing became worse and worse. The string had finally opened up to 4 inches at 100. I tore it down and the epoxy used on the "rear pillar" had broken loose. That would not have been a tremendous problem if the wood even remotely fit the action or if the pillar was actually long enough. The reason I put Pillar in quotation marks is because they are so thin they do not meet the requirements of a pillar in my book. In addition to that, the fit of the action to the stock is terrible. There are a couple of pressure points and a lot of area that does not contact. I did the wood work necessary today to glass bed it and as soon as I get a chance to get more bedding compound I will do what Savage should have considered doing if they were going to make a stock as light weight and weak as this design is. Savage is my favorite manufacturer, but this is not what I would expect from them on one of their higher end rifles. I would expect it on what I call their "throw away stock" rifles, but not their top of the line stuff.
 
* barrel's not properly stress relieved or has poor metalurgy distribution in it (rarely happens).
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I have a friend with a 77 in 223 and it vertically strung groups until we placed a piece of flat rubber under the barrel about two inches from the end of the fore stock. Bart B, wouldn't this indicate a barrel issue??
 
coyota1, a piece of flat rubber under the barrel about two inches from the end of the fore stock to improve accuracy does not indicate a barrel issue. That means the receiver's not held repeatedly in the stock at its location; something's a poor fit or loose. All that rubber spacer does is half-way corrects the stock's problem of not holding the receiver the same for each shot.

If the receiver's held firmly in place for each shot and the barrel's not touching anything, that barrel will whip, wiggle, vibrate or whatever exactly the same for each and every shot before the bullet leaves it.

reynolds357's issue with his stock in the receiver area is a good example. Same thing happened decades ago with the first synthetic stocks. Their material in the receiver area was too soft for proper stock screw torquing so someone came up with the idea to put big pillars around the stock screws so the stock core wouldn't compress too much.

Regarding Erno86's comments of which screw to torque in first, I don't think it matters as long as you start in each screw until you start to feel it tighten, then do all the others to the same place, then finally torque each one up. Not enough stock screw torque will cause vertical shot stringing; the barreled action whips too much and not the same amount for each shot vertically from shot to shot. That's the details behind reynolds357's issue.
 
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Bart B, The thing is, after the rifle cools down the POI is where it was when it was cold. After the barrel heats up it strings. It isn't random, which suggests that something is going on with the barrel. I am not trying to frustrate you, we are already there.
 
Coyota1, then that barrel's not properly stress relieved or fit correctly to the receiver. That happens a lot with factory barrels.
 
Bart, since we are discussing bedding I have a question I am sure you can answer for me. In all the instruction sheets, they show you put tape on front, sides, and bottom of recoil lug and release agent on the back. What is the point of the tape? Is it just to make releasing the recoil lug easier, or is it for accuracy purposes? I have always bedded just using release agent and no tape on the lug.
 
reynolds, the tape's put on the bottom of the recoil lug to allow clearance so the bottom of the receiver will clamp solidly to the bedding under it. If there was no clearance on the lug's bottom, it would not allow the epoxy to compress a tiny bit and allow full pressure contact all over its bottom. I use at least 1/32nd inch thick tape on the lug's bottom.

I don't put any tape on the sides or front of the recoil lug on my Win. 70 actions. Nor do I think it's needed on any other action type. Full contact with the bedding in those areas makes the receiver slide back into the same place each time it's pulled out of the bedding for cleaning.

I use Devcon Plastic Steel or MarineTex; these have the least amount of shrinkage when they harden. I've mixed a bit of baking flour with Devcon to make the mixture thicker and not run too much.
 
Thanks Bart. The tape on the bottom makes sense. I had always achieved this using tape on the barrel and toward the rear of the action. Makes sense to put it on the bottom of the lug.
 
I have seen articles where different stock screw torque levels would help tune the Savage.

Working on memory here (and I have CRS) I seem to remember the front action screw is torqued with a torqueometer first and then the rear action screw is tightened in steps.

I guess the place to start might be 50 inch pounds on front screw and 20 inch pounds on rear screw and shoot 3 and see. Then increase torque to 25 inch pounds, 30 inch pounds etc.

I had a Savage Scout in 7/08 and the rifle was extremely senstive to stock pressure if a Harris bipod was mounted. In order to get repeatability I had to adjust the rifle to where it had a natural point of aim and then very gently reach up and grasp it without disturbing the natural lay of the rifle POA.

Thusly I could keep it in a steel target cut to E silhouette dimensions and 635 yards. If I just grabbed it and tried to control where it pointed resulted in wild shots. I just saw a couple weeks back the same thing occur in a Savage 22-250 with a bipod and I knew the rifle was capable of 1" at 200 yards.
 
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