Vertical stringing

J

jaybic

Guest
Hello to all,

I am curious as to the cause of vertical stringing and or the cure. I have been reading the Centerfire forum and one thread mentions not having an vertical stringing issues so he had found his seating depth. Please mind that those were not his exact words but close.

How does one "tune" out a vertical stringing problem? All other things being equal, is it seating depth?

I have seen from my rifles some groups 1/2 inch wide by 2 inches up and down and am wondering if this is the that phenomenon.

Thanks to all,

Jaybic
 
Vertical stringing can be attributed to several things.....

If I were to assume that there were no stock issues, to cure vertical stringing, I usually change primers to a hotter primer or add more powder.
 
Vertical Stringing

Someone chime in if I am mislead but isn't vertical stringing caused by a straightened barrel trying to go back to its origninal shape due to heating/overheating? The only cures that I am aware of is either:

1. keeping the barrel cool and not shooting too many times without cooling down,
2. having the barrel cryogenically cooled to 300 degrees below zero and gradually brought back to room temperature, or
3. buying a rifle (like the Remington 40XB Rangemaster) that does not use straightened barrels!

I prefer number three!! :D
 
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Here is a link to 6mmbr that lists some casues of vertical stringing , while it pertains to full blown benchrest , most should still apply to other rifles.

In the "load tuning" section there is mention of switching primers.

• Primers--If you're getting vertical, and everything else looks fine, try another brand of primers. And remove the carbon from the primer pockets so the primers seat uniformly every time.
Click to expand...

http://www.6mmbr.com/verticaltips.html
 
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Are you using a 1pc or 2 pc base? What type of receiver is it?
 
It is an Abolt Microhunter in 22-250 with a 20 in barrel. Its a very light, short rifle with Leupold 2 piece with front dovetail and rear windage adjustable mounts. Its about 3 years old with about 500 rounds +/- thru it. It seems my DPMS .223 will do it also so maybe bench technique(ME) is the problem also.

It has never been bedded other that the Browning factory job. Are they know to do a decent bedding job?

Thanks fellas,

Jaybic
 
You have a rifle with a thin profile barrel, that are prone to stringing as they warm up...Some things to try....
Ensure the scope bases are tight, check individually with rings removed..
Most Browning have free-floated barrels, check yours and verify...
Check action screws front and rear, don't overtighten, about 35-45 inch pounds maximum..
Ensure you are shooting off of a quality rest and bags..(not pillows or shot bags, etc..)
Pick a calm day with overcast skys to test..
Keep the barrel cool while sighting or load testing..If necessary use Brake Cleaner sprayed into the barrel to cool from the inside out...patch out wetness before shooting..
Check scope mounts ensure they are rigid...
If using factory loads, try several brands...
If handloading get some help, ensure you are carefully loading without variation in powder charge, neck tension, and seating depth..
Start with some new brass, and use recommended powder of new manufacture..(some handloader use powder that they have plenty of, or that is the cheapest. If you are shooting a 22-250 you can't go wrong with Hogdons H380...
As a last resort have the barrelled action Cryogenic treated that may take the stress out of the barrel..

Keep us posted.

Eddie in Texas
 
Thanks Eddie/eww1350,

I do handload and I considered myself quite knowledgeable right up until I discoverd this website and I have since demoted myself to "the village idiot" of reloading.:)

Anyway, I just bought a RCBS Casemaster to upgrade my load quality and I have checked over most things that you have mentioned but did miss a couple ideas. I have maybe a dozen powders I have tried and h4895 and Varget appear to do the best by me so far. I have to play with h380 and h414 some more.

Did not know action screw tension played a role. I just tightened them good and hard, maybe too much but I dont have a torque wrench to know for sure.

Is it possible its a bedding issue. I have a buddy whose barrel was not floated all the way and he put a piece of matchbook under the recoil lug and it got better I guess. There has to be a better way than that.

Thanks again,

Jaybic
 
Jaybic

I think the Browning A-Bolt rifles have the hot glue bedding around the recoil lug...I suggest that using your best handload seat the bullet out to maximum that will fit into the magazine with 1/16th" clearance..then start by backing out the front and rear action screws until loose..then with the rifle vertical tighten the front screw until it makes contact with the bottom metal..then turn 3/4 turn in and stop..then turn in the rear action screw just enough tension to keep it from falling out..then fire 3 shot groups and tighten the rear screw 1/4 to 1/2 turn at a time..don't overtighten...If it starts to shoot, then using a pencil mark the screw and stock then back it out counting the turns until it is removable..then apply some "blue" locktite thread sealer and turn it back in to the exact spot.

Let us know if this helps...

Weatherby sells their "minute of angle" Mark V rifle with a synthetic stock and it comes with instructions NOT to tighten the screws more than 35 in.lbs.


I used to have a Savage .223 heavy barrel rifle that would not shoot untill I went thru the procedure I described to you..It will shoot 1/2" groups regularly.
 
It could be

Your bench set up and or shooting technique.

It isn't easy to shoot small groups, even with good equipment.

Example: One of the best things I've done to improve groups from the bench is to fill my rear bag with #8 lead shot.

I would also recommend a stop on the front rest, this will help the rifle to go back into the some spot every shot.

Your set up should not move during or between shots.

All this stuff is much harder to do with a hunting style rifle.
 
as far as bedding goes take it out to Coyote Creek and have Clint take a look at it he's a fair guy to deal with.
 
A problem with 300WM

After 2-3 shots the group would start to string upwards and then to the left. As this pattern would reoccurre with three different powders, two primers and two bullets I'm now convinced it was a tension in the barrel steel itself.
After having the barrel double stress relieved, I hope to fix the problem.

Shoot better
Peter
 
jaybic, when you are shooting a light weight rifle.....

things are just a little bit more complicated. How you grip the gun from shot to shot is critical, how much Shoulder you put into the gun is critical.

I have had excellent luck getting Brownings to be very accurate. In many calibers. One thing that I did find is that you have to hold the forearm down, you can't just let it lay on the front bag. If you do not hold down the forearm, then you will get all kinds of vertical.

If you replace the spring in your trigger with an ink pen spring, you will have a 1 1/2-2lb lb trigger for bench work, replace it with the factory spring for hunting.

The Brownings that I have worked with all liked to have the bullet seated to kiss the lands, all of them.

When you are shooting, do not let your barrel get hot. I use a solution of 50/50 rubbing alcohol/water with a soaking wet rag. Rub the barrel till the solution is dripping off the barrel, and it will cool the barrel very fast. When you get home, oil the barel if it is a chrome moly barrel.

If you are shooting out in exposed sunlight, do not let your rounds be exposed to sunlight in warm weather, it will really heat up the round causing wild pressure changes.

As you place your gun on the bags, be sure that the front bag is no further out than half of the forearm, placing the gun on the bags near near the forearm tip causes all kinds of flyers.

NEVER have the sling swivel in the center of the front bag, NEVER!

In my experience, vertical means that you have a problem with the barrel touching the forearm, or you need to add more powder or a hotter primer.

Good luck!
 
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