Vertical stringing

[fastnflat1]

What is the most common cause for vertical stringing in groups?

I had an action trued and new bbl installed and am having a heck of a time getting vertical string tuned out.
Ive had it in 2 different stocks, tried various seating depths, different primers, free recoil and firm grip technique and no luck yet.

My next try will be a different scope. Just curious as to what the pros here have found to cause this to happen.

 

[snert]

Have you checked with a chrono? Varied velocity show up as vertical.

Most of my vertical is how the gun rides the bags or some other sort of recoil management issue.

 

[ShootDots]

Have you checked with a chrono? Varied velocity show up as vertical.

Most of my vertical is how the gun rides the bags or some other sort of recoil management issue.

^^^ This is the biggest culprit. I think that in many occasions, the rifle is not riding correctly because it is excessively nose heavy, causing the vertical stringing.. Counter-weight or flute the barrel>>>that, many times, will fix a problem that can not be fixed with seating depth changes, powder changes etc...etc..

 

[Greyfox]

Could be a lot of things, but you asked the most common. IMO the most common reason is that the rifle is out of tune, meaning you should go up or down in powder charges in small increments and see if that corrects the problem.
It's also the easiest to correct.

Rick

 

[expiper]

OP....more powder ,,,or,,,hold down on the back of the gun with your thumb on the comb...Roger

 

[Subsilent22]

My latest experience, which Ive put a few barrels on over the last year. Anyhow, I had my action re-trued by another smith and my barrel set back the last go around. Took it out with the same loads that had previously held 3/4in groups at 300 and the gun wouldn't hold a MOA. I went home and got my reloading gear and headed back to the range to re-tune my load thinking this was the problem. (This is my F-Class gun that has won a few comps and placed 3rd in Master class at Berger Nats) On the way back to the range I started thinking about the possibilities of what was going on with the load when I remembered about my Savage hunting rifle, which is bone stock. I remembered that after working up a good load with that rifle I started messing around with torque settings on the action screws and actually tightened my groups up by a whole inch at 300 yards. So I decided to try this on my F-Class gun before going back through and redeveloping a load. I brought my front screw up from 45in lbs to 51in lbs and my rear from 45in lbs to 48in lbs and BINGO!! It went right back to shooting 3/4in groups. Just food for thought!!

 

[fastnflat1]

Thx for the shared experience and knowledge! The bbl is a M40 contour finished at 26". With a scope mounted and in a laminate stock the balance point is about 2" in front of the recoil lug. The gun doesnt feel nose heavy much at all.

5 shot ES is in the hi 20s to low 30s. thats the best I could find starting low and working up to max load.
I was expecting better than that but couldnt achieve it.

This setup is chambered in a 243 Improved variant and I'm running H4831sc with CCI primers and a 105vld.

I've used 2 different configurations for brass. One being Lapua 308 palma brass worked down to 243 and the second being Lapua 243 win brass.

The palma brass with cci-450 primers showed no sign of hangfires or problems igniting the powder column and had very similar velocity readings to the 243 brass with cci-Br2 primers. However both configurations exibit the vertical stringing.

The stringing is equivalant to 1moa basically. Shot out to 600yds It had about 7 inches of vertical and
3inches of horizontal.

When I shot it at 600 it was set up in a chassis with a harris bipod in prone off of a mat with a rear sandbag. Tonight I shot it in a laminate vls stock with a benchrest type setup on bags on a bench at 100yds and I get about 1 inch of vertical.

I'm gettin close to 300rds down the tube now and am startin to go gray over the thing LOL.

I do like challenges but this is startn to get to me.

Even though it seems to be tracking fine I am going to try another scope just to be sure.

 

[fredhorace77]

one thing you might check is to make sure you have significant clearance in the barrel channel of the stock. sometimes theres not enough room and when a longer barrel is used, say 26"or longer, the barrel vibrates more and needs more room in the barrel channel to move. basically your barrel could be bouncing off of the stock somewhere in the barrel channel. just a thought.

 

[Immike]

If the rifle is jumping in the bags, make sure the bags are soft and rest it further back on the stock. Barrel flip will create a lot of vertical. Push it forward until it quits jumping.

 

[fredhorace77]

If the rifle is jumping in the bags, make sure the bags are soft and rest it further back on the stock. Barrel flip will create a lot of vertical. Push it forward until it quits jumping.

+1 i have seen this help alot.

 

[masterblaster1]

anneal your brass verify headspace

 

[Tim Singleton]

If the rifle is jumping in the bags, make sure the bags are soft and rest it further back on the stock. Barrel flip will create a lot of vertical. Push it forward until it quits jumping.

Soft bag IMO critical

 

[alintx]

Plus one on the bag powder. Free recoil can real finicky about it altho its my favorite. Thumb on top was next pick of the solutions above, Closely followed by recoil lug over the tripod. Good luck and let us know if you solve it !

 

[LHSmith]

Excessive trigger pull, front bag too hard, inconsistent distance from butt stock to shoulder in free recoil, inconsistent hold when shooting firm grip style, powder charge ( go up or down), rear bag not firm enough causing ears to settle lower from each shot, inconsistent placement of stock in bags (did you use a fore-end stop on the rest?), fore-end stop not padded, rushing shots in attempt to try to run and gun causing one to jerk trigger, inconsistent bag friction, swivel studs hitting bags.
Remember the bullet is still in the barrel in the very early stage of recoil. So any contact with the gun has to be exactly the same in order not to influence POI.
This is where having a precisely "timed" action/ trigger group and full length sizing to 0.002" bump (from measured H/S) will shine = absolute minimum bag upset. Each time you cycle the bolt on less than optimum set-ups, you are displacing the sand in the bag to the point where the bag support becomes unstable.
Describe your bi-pod w/ rear bag and "BR type" set-ups.

 

[dkhunt14]

I always had better luck with the VLDS in the lands .010. This was especially true at long range. I would try another powder or primer. Matt

 

[jsthntn247]

What is the most common cause for vertical stringing in groups?

I had an action trued and new bbl installed and am having a heck of a time getting vertical string tuned out.
Ive had it in 2 different stocks, tried various seating depths, different primers, free recoil and firm grip technique and no luck yet.

My next try will be a different scope. Just curious as to what the pros here have found to cause this to happen.

Seems like you tried everything but varying your powder charge. To me powder adjustment gets the vertical out and seating depth and neck tension get the horizontal out. If your not in a solid node, nothing else you do is going to help.

 

[BoydAllen]

Tell us about the action bedding in the various stocks. I think that having perfect bedding is very important to accuracy. If the action was trued. particularly if a cut was made on front of the receiver to true it, and or if a recoil lug could have been installed in a slightly different position, the bedding would have to be redone. Have you checked your bedding with a dial indicator?

 

[22BRGUY]

Maybe silly...how did your ladder tests work out?

 

[fastnflat1]

A buddy stopped by yesterday and hes a shooter/reloader so I asked him to shoot my setup. His groups were similar to mine and actually a bit larger so that comforts my thoughts of it possibly being me LOL.

My "benchrest type setup" is not what some of you would call "benchrest" but I have worked loads and tuned other rifles with this setup to achieve groups in the .3s, and that is typically my norm if the rifle is capable of doing so.

A jewell trigger is installed on this rifle also, so a heavy or sloppy trigger is not the problem either.

As far as my bedding goes, the stocks were not bedded before the re-bbl and I have since bedded the stocks hoping to improve performance. I seriously dont suspect a bad bedding job as the rifle shoots worse after truing and re-bbl than it did as a factory remington setup. And yes that was before I bedded either stock.



Load development with H4831sc started at 44gr and worked up to 48gr. I could only go to 48gr in the palma brass with small rifle primers as the large rifle brass wouldnt stand the pressure. I never could see any sign from the groups that said pick me, pick me, so I based the pick of 46.5 on velocity readings. No, thats not what was the fastest but there was show of a "Node" in the way that velocity plateaued at 46, 46.5 and 47gr. I figured from there I would tune it with seating depth. It started to show some good sign of coming around but has since began to go backwards.

I think i'm gonna wipe the slate clean and start over, redoing ladder tests and see where I end up.

The bbl doesnt copper much and cleans up really quick and nice. Its actually one of the better bbls I have for cleaning (is that a sign? lol) I dont think its a bbl issue but who am I to say.

Could fault be in the chamber job or crowning? I'd say so, but I'm not goin down that road until I go back and redo my load testing.

 

[Tim Singleton]

Its frustrating. But some barrels just refuse to shoot