Shooting Technique -- horizontal stringing

[zupatun]

At lunch went out to do a little practice. Shot at 100yds and 200yds because the range max is 200. Used caldwell adjustable rest and rear bag. Shooting Tikka T3 SS Varmint in 308 Winchester. Federal Fusion 165's. I waited 3 minutes between shots. Wind directly from behind gusting between 3 to 10mph averaging around 4mph (so it seemed to me). 55F outside, elev 1067ft Western PA.

Results at 100yes. Max vertical measurement between 5 shots is about .52" - 0.308 = 0.212 off the caldwell at 100yes. Horizontallly, outside measurement is 1.375"-.3" = 1.067.

My rest is very steady. I'm leaning into it with slight downpressure on my cheek to get the crosshairs to come up about 1/2" to dead nuts center (DNC)at 100. Any reason why my horizontal stringing is so much larger than the vertical stringing--anything with technique that is easily diagnosed. Truthfully, I should have looked this up and done more research, but this is enough time screwing around on the web--so I have to get back to work.

Any experience or advice is appreciated. P.S. 200yd group off the bipod with the back supported by my fist is about a 3" group vertically and about 1.5" horizontally. Actually I find shooting off the bipod like this more comfortable than the caldwell and rear bag.

/ubbthreads/images/graemlins/confused.gif

 

[eddief]

Matt,

Make sure your front bag on your Caldwell isn't too hard, this will cause vertical lots of times. They just need to be slightly firm, not hard or your rifle will bounce under recoil, but you won't notice it because it happens so fast. Also be consistent with your shoulder pressure.

Eddie Fosnaugh

 

[Buffalobob]

Matt

I spent hours and hours searching this forum, 6mmBR, BR and another looking for the cures for horizontal grouping. There was someone who posted the same question about a month ago and all they got was advice on vertical grouping and comments about reading the wind.

About 5 months ago I bought my first front rest and rear rabbit ear bag. The groups suddenly went horizontal for the little light 17 Rem except for an occasional low one. I switched to a hotter primer and cured the occasional low one so that my groups are just like yours. Totally no vertical dispersion but wider than the Mississippi River!!! Conventional measurement said my groups went from 0.5 MOA to 1.0+MOA but it was all horizontal. That was when I began the search of the internet.

All I found was one passing comment by Speedy Gonzales on "alignment of the rear bag". I checked and sure enough I never ever get mine lined up correctly. But I do not believe that can account for a full inch of horizontal at 100 yds.

 

[Buffalobob]

After I posted that it occurred to me maybe I had been using the wrong words to Google. So I tried again.

Here is what Varmint Al has to say (although I do not understand why sandbags give one shape group and a front rest another.


TRIGGER CONTROL.... Ever wonder why benchrest shooters use triggers that have 2 ounce pulls, or less? Well, look at it this way. Let's assume the front of the rifle was fixed couldn't move. If while you were pulling the trigger, you just moved the rear of the rifle just 1/100th of an inch, you've just changed your POI about and 1.5 inches. JUST 1/00th OF AN INCH and you've just blown your group! So, it stands to reason, the more force you must exert on your trigger to release the sear, the more the rifle will move. I like to think of it this way. A two pound trigger requires half the force of a 4 pound trigger (32 oz Vs 64 oz). So, a 2 oz trigger requires 1/16th the force of a two pound trigger (2 oz vs. 32 oz)!
I can't tell you how many rifles have had amazing improvements in groups, just by changing to a competition trigger, or at least having it adjusted as low as you can get it. This is the first thing you should do to a rifle that you're expecting great things from. WARNING! Triggers are very touchy and sensitive mechanisms. If you are not sure what you are doing, have a gunsmith adjust your trigger and test it. <font color="red">
Now, test what your trigger pull is doing. You don't need ammo for this. I like to start with the gun cocked and the safety on just so you can see how much your crosshairs move when you pull on the trigger. Get set up like you're ready to shoot and aimed at the bull. Now squeeze the trigger, while keeping a very close eye on the bull and the crosshairs. Did the crosshairs move? Then expect it to move when you shoot for real. Now play around with different positions for your trigger hand and thumb. I'll bet you if you place your thumb on the side of the stock that you will get lateral movement when you pull the trigger. A better place to put your thumb is on top of the tang or not place it at all. Some benchrest shooters will place their thumb on the back of the trigger guard, and just squeeze thumb and trigger finger together to fire. </font> Whatever method you use, you should be able to exert enough force on your trigger be it 2 ounces or 2 pounds without causing the crosshairs to move on the bull. Practice this.

 

[rwleonard]

I remember shooting a 6-round group with my 308 several years ago. On three of the shots I saw the reticle track straight back toward me,on the other three, the rife torqued and the scope went black. I got two distinct groups, each about .3 MOA but nearly an inch apart, all horizontal. A 308 has enough recoil to make consistent control of tht recoil critical to shooting little groups. I find that if I have any tension across the back of my neck and shoulders, I get horizontal stringing.

Rick

 

[JR]

When shooting groups, try not to change your position behind the rifle much..If you have to sit out a gust, don't get up and have a sandwich inbetween..

"Wind directly from behind gusting between 3 to 10mph averaging around 4mph (so it seemed to me)."

Ha..but tailwind can be a bitch, you never know which way it switches..

Check your parallax is correct for the range as well..

JR

 

[zupatun]

Thanks all,

Some things to think about and try. I'll definitely play with my thumb position and the front bag was pretty firm. I'll have to re-read and gameplan before I go out and practice next week. Again, thanks.

 

[wapiti13]

Matt, didn't see you talk about possible parallax issue. Depending on your scope, is it parallax adjustable? If not, most scopes are set at 150yds by the factory. You are shooting at 100 &amp; 200 yds. Head movement in your scope can cause a visual error. You must weld your eye in your scope to be repeatable. Just a thought.

 

[zupatun]

Well, I haven't been to the range all summer, but took my handload I worked on in the winter out to the range. The velocity looks like it is now about 2675 instead of 2750 (calculated, I don't have a chrono...) because the drop is about 1moa lower at 300yds than I expected. That said, my horizontal stringing at 300 yards is about 1.5MOA or about 4.5". The vertical is about 0.24 MOA. I was using a bag on top of a block of wood for the front and a monopod for the rear with a firm grip but relaxed trigger finger.

Load was 44.5Gr Varget with a 165gr IB for 308 win brass in my Tikka T3 (Tubbs FF smoothed barrel) Varmint. I waited 5 minutes between shots. Ambient temps were around 85 deg. wind was dead still up and down the range.

Same issues as back when with horizontal stringing. I am using good finger placement, but as I haven't practiced much maybe my grip and thumb placement hasn't been very repeatable. Also, while I have parallax adjusted for 300yds the crosshairs are freqently out of focus even when the target is in focus. I'm finding it hard to keep both in focus. I was really focusing on relaxing my breathing, and not anticipating...

Any comments are welcome. Plan on going out next Monday to see if I can repeat or improve on these results. Not horrible for the first trip this year, but not great either.

Matt

 

[royinidaho]

First I'd read all the replies to Ian's posts re: basic marksmanship and sort out the responses.

Next I'd ensure that parallax is out of the scope at the target distance.

Third I'd ensure that the front rest is not flat and wider than the forearm. If it is stick 1/4" plastic pipe or dowels or something to shape it into a wedge to hold the fore arm.

Next, when shooting, ensure the non-trigger hand is on the rear bag not the forearm.

Next I'd get away from using the cheek weld to adjust the final height of the point of aim. Squeeze the rear bag for that. Ensure that with only the one hand touching the rear bag, that the natural point of aim remains when the rest of the body parts are removed from touching the rifle.

Lastly, if the horizontal spread persists, bump the powder up a notch then down a notch and note any change. I find that often I shot a | string followed by a -- string at different powder charges and shot a * when the powder is mid way between the two extremes.

And finally, buy powder in 8# cannisters and primers by the 1K to save trips to the store.

 

[Surveyor]

When I hear horizontal stringing, the major players are parallax, trigger (causing a last nanosecond pull), barrel making side contact (not adequately free floated), scope or scope mount and heard possibly crown.

Usually I ask if the string was incremental (1st on .5 inch, 2nd 1", 3rd shot 1.5" in the same direction). This usually points to barrel or bedding. If the shots are willy nilly, both sides of P.O. aim, then parallax or scope. Willy nilly on one side of PO aim, then trigger.

 

[James H]

First I'd read all the replies to Ian's posts re: basic marksmanship and sort out the responses.

Next I'd ensure that parallax is out of the scope at the target distance.

Third I'd ensure that the front rest is not flat and wider than the forearm. If it is stick 1/4" plastic pipe or dowels or something to shape it into a wedge to hold the fore arm.

Next, when shooting, ensure the non-trigger hand is on the rear bag not the forearm.

Next I'd get away from using the cheek weld to adjust the final height of the point of aim. Squeeze the rear bag for that. Ensure that with only the one hand touching the rear bag, that the natural point of aim remains when the rest of the body parts are removed from touching the rifle.

Lastly, if the horizontal spread persists, bump the powder up a notch then down a notch and note any change. I find that often I shot a | string followed by a -- string at different powder charges and shot a * when the powder is mid way between the two extremes.

And finally, buy powder in 8# cannisters and primers by the 1K to save trips to the store.

Roy I gotta agree with you.
Never apply downward or sideward pressure to the stock, use your non-trigger hand to squeeze the rear bag to bring the X-hairs to the point of aim if you are too low adjust the front rest. If I need to use the rear bag to adjust more than about 1/4 minute I will adjust the front rest (it is really better if you do zero horizontal adjustment with the rear bag).

Personally I have never had a horizontal stringing problem that could be traced back to the load, it's always been missing the wind or bag handling.
When you adjust the paralax don't just focus the image, look through the scope and move your head around and see if the X-hairs move, if they do the scope paralax is not adjusted properly.
James

 

[edge]

About a year ago I posted the same question and got the Varmint Al reply. It made a huge difference in my groups moving the thumb from the side of the rifle to the tang. I have been a shotgun shooter most of my life and tend to slap the trigger. Changing from a 3 pound trigger to a 1 1/2 pound trigger and moving the thumb helped a lot.

My groups almost always had this type of a pattern:

45 caliber muzzleloader shooting 150 grain 30 caliber Accubonds.

edge.

 

[Boss Hoss]

Speedy put this together and is a good read:

Tips on Vertical Problems


1. A lot of rifles are muzzle heavy. Some rifles have too heavy a barrel and this causes vertical problems, especially those who shoot free recoil

2. Firing pin coming out of hole in bolt in the cocked position. This will cause poor ignition. Take bolt out of rifle and look in firing pin hole. If you cannot see entire end of firing pin it has come out of the hole.

3. Firing pin dragging in bolt or shroud. Listen to the sound when you dry fire. If not the same sound each shot something is wrong.

4. Trigger sear too much spring. Hold trigger in firing position and push down on sear with your thumb. If it is hard to push down, this will cause vertical problems.

5. Firing pin spring too weak or too strong will cause vertical problems. If you think this is the problem change springs and see what happens.

6. Tightening front sand bag too tight on stock. When you try to pull rifle back by hand and rifle feels like it is stuck in the bag it is too tight. Rifle should move in sand bags evenly, not jerk or chatter when pulling back by hand.

7. Action not level with top of stock running down at muzzle end. Rifle will recoil up at butt end causing vertical.

8. The load that are shooting can too light or heavy and can cause vertical problems.

9. Bench technique not same every shot. One example, should against stock one shot and not the next.

10. Bad primers – if getting vertical try other primers.

11. Bad scope, if scope is bad from shooting vertical, if you change your load in anyway and vertical goes away it is not your scope.

12. Rifle not balanced, it does not recoil right, jumps in bag. If rifle is built properly this will not happen.

13. Some stocks are very flexible. This can cause vertical.

14. Front sandbag too hard. I personally have never had a rifle that will shoot consistent with a rock hard front sandbag. It always causes vertical or other unexplained shots.



Other Tips:

1. Head on front rest loose. A lot of rests have movement even when you tighten them as much as you can. This can cause unexplained shots.

2. Some 30 mm scope rings are not getting tight enough to hold scope. Scope slipping in rings under recoil. This will cause point of aim movement.

3. Keep shell holders clean, in press and priming tool. I have seen so much dirt in shell holders that cases are sized crocked on body. Also primers cutting primer pockets bigger shaving brass as you seat the primer.

4. Whenever you can, set up so you can load watching conditions on the range as you load your ammo. That way you will be aware of any changes in conditions since your last group and you will be mentally prepared for the new condition.

5. Learn to look at whole field of flags, not just the row in front of you. A lot of times conditions change away from you will cause shot to go out of group before change in condition shows up in front of your bench.

6. When you chamfer the inside of your case necks make sure they are smooth enough that they don't peel jacket material off when you seat the bullet.

7. I see people walking around with case necks turned up in the loading block. A lot of the time there is condensation dropping from the roof of your loading area. If one drop of water gets in case you are in trouble on the shot. How many times have you had a bad low shot when it has been raining and you have been walking around with your cases turned up in your block?

8. Learn to keep head down and follow through when you are shooting each shot.

9. I hear a lot of discussion about low shots in a group and apparently this occurs a lot on the fifth shot. If it is your 5th shot most of the time you can bet you are doing something at the bench.

10. If 5th shot is a problem, which everyone does at times, we do what I call wishing the last shot in. We just aim, pull the trigger, and do not worry about the wind flags.

11. This year alone I have seen nine lock rings on scopes that are not tight. Guess what that does to your group? Make sure yours are tight.

12. When you realize that the wind is your friend you will become a much better benchrest shooter.

13. Practice in wind, not in good condition.

14. Pay attention to angle changes on flags. Even though you see the same color angle changes make a big difference in your groups.

15. The longer you wait between shots when a condition is changing the more the condition change will affect your bullet.

16. If you do not know how to read wind flags or have never seen a wind flag try to shoot your group with the flags all going in one direction.

17. Equipment at bench has to work flawlessly. If it doesn't get it fixed or get rid of it. We need all our attention on wind flags.

18. Learn to shoot with both eyes open so you can see more of the conditions.

19. Free recoil shooters should be sure rifle hits shoulder squarely on recoil, not on edge of shoulder or muscle of arm.

20. Should have your own stool to sit on so that you can sit at the bench comfortably for you.

21. Hunting rifle barrels – do not get cleaned enough. If you keep barrel clean it will shoot better for you. You should clean barrel good after every 10 to 12 shots.

22. Most hunting rifles will not put first shot after cleaning with rest of shots. So after cleaning if you have a rifle that won't group first shot shoot one fouling shot before going hunting or before you shoot for group size.

23. When working up a load for your hunting rifle take your time and do not let the barrel get hot on you.