spannulman
Well-Known Member
Someone told me in a Gunshop that shot strings in a line were due to loose stock bolts. They said front stock bolt made the line of shots go vertical and the rear bolt horizontal, or vice versa.
But then someone I met on the moors with a pointer said it lifts the front leg pointing feather and rear for fur- so I may be having my leg pulled. I’m away to the stores dept for a ‘long weight’......
But then someone I met on the moors with a pointer said it lifts the front leg pointing feather and rear for fur- so I may be having my leg pulled. I’m away to the stores dept for a ‘long weight’......
Heym SR20
Well-Known Member
Vertical grouping will be a mix of:
1) Barrel heating - you are using a lever action where the magazine tube is attached to barrel. Vertical stringing is well known and understood in a combination or double - all barrels heat up. If one side of the barrel is fixed to another barrel or tube it will warp upwards or downwards (or sideways in the case of a side by side). Don't know if this effects lever actions.
2) Inconsistent hold and body position - you are gripping rifle differently with each shot.
3) Trigger squeeze, break and sight alignment.
Ignoring barrel heating, it doesn't take very much to throw bullets off a bit. Assuming you are using a typical breath in / breath out technique with the squeeze coming in as sights are aligned a slightly early or late break of the trigger will cause shot to go off. You say that you need a firm squeeze on the lever - I would use a firm squeeze on both hands as the sights are aligned and the firm squeeze will release the trigger. Given that you have had by the sounds of it issues of the trigger not falling, you may well be getting a flinch.
Also remember that lever actions are not precision target or bench rest rifles. They were designed to get multiple quick shots onto a reasonably close and reasonably large target in a defensive type situation.
1) Barrel heating - you are using a lever action where the magazine tube is attached to barrel. Vertical stringing is well known and understood in a combination or double - all barrels heat up. If one side of the barrel is fixed to another barrel or tube it will warp upwards or downwards (or sideways in the case of a side by side). Don't know if this effects lever actions.
2) Inconsistent hold and body position - you are gripping rifle differently with each shot.
3) Trigger squeeze, break and sight alignment.
Ignoring barrel heating, it doesn't take very much to throw bullets off a bit. Assuming you are using a typical breath in / breath out technique with the squeeze coming in as sights are aligned a slightly early or late break of the trigger will cause shot to go off. You say that you need a firm squeeze on the lever - I would use a firm squeeze on both hands as the sights are aligned and the firm squeeze will release the trigger. Given that you have had by the sounds of it issues of the trigger not falling, you may well be getting a flinch.
Also remember that lever actions are not precision target or bench rest rifles. They were designed to get multiple quick shots onto a reasonably close and reasonably large target in a defensive type situation.
phillips321
Well-Known Member
Wont also inconsistent load data also potentially be a factor? If the FPS deviates too much then this could cause the point of aim to be higher/lower?
Heym SR20
Well-Known Member
This is an interesting read. Shooting - Group diagnosis
And rereading the OP. When reloading vertical stringing probably means you are well away from an accuracy node, all other things being equal. Last couple of loads I have worked up, I have loaded up 10 rounds starting at bottom and getting close to top. Fire them slowly - cold barrel - at the same target noting point of impact. There will be an element of vertical distribution, but you may we’ll find clusters of rounds of adjacent loadings. Pick the middle of these and go from there. With the correct load, a little variation in powder won’t make much difference. If the load is not at a sweet spot, a little variation can make a big diffference.
And rereading the OP. When reloading vertical stringing probably means you are well away from an accuracy node, all other things being equal. Last couple of loads I have worked up, I have loaded up 10 rounds starting at bottom and getting close to top. Fire them slowly - cold barrel - at the same target noting point of impact. There will be an element of vertical distribution, but you may we’ll find clusters of rounds of adjacent loadings. Pick the middle of these and go from there. With the correct load, a little variation in powder won’t make much difference. If the load is not at a sweet spot, a little variation can make a big diffference.
This is from yesterday, me versus the wife.
The group on the right was shot first (1-3), cool barrel to start, quite warm at the end. The group on the left was shot second (4-6), and we were worried about a thunderstorm overhead so they were shot quickly quite soon after shots 1-3, and the barrel was pretty hot by the end. The vertical stringing was immediately obvious, in sequence they go 4, 5 above 4, 6 above 5.
Tikka T3 sporter contour, 308.
The group on the right was shot first (1-3), cool barrel to start, quite warm at the end. The group on the left was shot second (4-6), and we were worried about a thunderstorm overhead so they were shot quickly quite soon after shots 1-3, and the barrel was pretty hot by the end. The vertical stringing was immediately obvious, in sequence they go 4, 5 above 4, 6 above 5.
Tikka T3 sporter contour, 308.
Hi Dodgyknees, on your right hand target, where you've got two shots touching followed by one a little wide, are you saying that shots 1 & 2 are the touching shots, with shot 3 being wide one? And you're attributing the difference to the fact that the barrel was a bit warm by the time the 3rd shot was fired? Only asking because all my 3 shot groups from my 270 look like that, and I was wondering why.
No, the barrel heat affected the group on the left. Sorry I haven’t explained it very clearly.
The right-hand group was shot by my wife. She’s a better shot than me and often wins our little competitions! Not yesterday though... thank god for that as I’d lost the previous four.
Shot 1 was the lefthand of the two touching, shot 2 was the one to the far right, shot 3 was the righthand of the two touching. If you could see how they were being shot - standing on a slope leaning into the canopy of the Hilux, with the rifle on a bag which was on top of a plastic box, no rear support, then the drift to the right with shot 2 is easily explained.
Then I took over, shot 4 was the lowest of the string on the lefthand target, shot 5 just above it, shot 6 above that. Because we were genuinely concerned about getting struck by lightning I didn’t give the rifle much time to cool after the wife’s string. So by the time it got to shot 5 it was hot, shot 6 properly hot.
The vertical drift of POI is pretty typical for this sporter contour T3 and my similar 243 Howa. But my varmint contour (0.870” at the crown) Tikka and similar Howa never get this kind of heat related POI drift and I shoot much longer strings with those, often 6,7,8 shots one after the other when I’m onto a mob. I’ve tested that on paper with these rifles to get confidence that if I shift from 200m goats to 500m goats in the same string, I’m not going to have to take a wandering POI into account.
That’s why I love heavy barrel varmint rifles.
This kind of shooting replicates pretty close what we do when driving farm tracks looking for goats, either off the bonnet or out the back of the canopy.
The right-hand group was shot by my wife. She’s a better shot than me and often wins our little competitions! Not yesterday though... thank god for that as I’d lost the previous four.
Shot 1 was the lefthand of the two touching, shot 2 was the one to the far right, shot 3 was the righthand of the two touching. If you could see how they were being shot - standing on a slope leaning into the canopy of the Hilux, with the rifle on a bag which was on top of a plastic box, no rear support, then the drift to the right with shot 2 is easily explained.
Then I took over, shot 4 was the lowest of the string on the lefthand target, shot 5 just above it, shot 6 above that. Because we were genuinely concerned about getting struck by lightning I didn’t give the rifle much time to cool after the wife’s string. So by the time it got to shot 5 it was hot, shot 6 properly hot.
The vertical drift of POI is pretty typical for this sporter contour T3 and my similar 243 Howa. But my varmint contour (0.870” at the crown) Tikka and similar Howa never get this kind of heat related POI drift and I shoot much longer strings with those, often 6,7,8 shots one after the other when I’m onto a mob. I’ve tested that on paper with these rifles to get confidence that if I shift from 200m goats to 500m goats in the same string, I’m not going to have to take a wandering POI into account.
That’s why I love heavy barrel varmint rifles.
This kind of shooting replicates pretty close what we do when driving farm tracks looking for goats, either off the bonnet or out the back of the canopy.
I would say not, but it would depend on the size of your groups and whether the average POI is in the same place group to group.
One of the groups I shot today was in a strikingly vertical arrangement but I reckoned it was just a random event...the excellent Fuller group diagnosis article explained it adequately, I didn't look for anything more esoteric, the group could of been any shape around a similar POI I suspect. It was the first trial of a group with Fox bullets at the factory load so I will load a few more and see what happens at the same load, but also work up to few a bit faster at the load I worked up to with the Barnes TTSX 130gr. I tried the TTSX today loaded with the same 2.91g as the Fox 130gr factory load today just out of interest.
Apart from Shooting - Group diagnosis there are a couple of other articles which may help...
CURES for VERTICAL STRINGING
...and I can't remember where I copied this from...
Re: What causes horizontal and vertical strings
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What some folks are saying about vertical shot stringing in this thread is, IMHO, way off base; probably out of the ball park.
Consider the fact that a .308 Win. has a 2/10ths inch vertical shot stringing at 100 yards for a 100 fps spread in muzzle velocity. And a .300 Win. Mag. shooting 180-gr. spitzer boattails out at about 3000 fps with a 100 fps spread in muzzle velocity has vertical shot stringing at 200 yards of about 6/10ths of an inch. If vertical shot stringing is more than this, there's something else causing it. And a rifle capable of 1/8th MOA groups of the shooter at these ranges is needed to see these effects of a 100 fps spread in muzzle velocity.
Most common problem shouldering a rifle as it rests on something atop a bench is where the butt plate's put in the shoulder; too low and shots go high; too high and shots tend to go lower. In second place is how hard one bears down on the rifle's cheek piece with their own head; too hard and shots go low, too soft and shots go high.
Horizontal shot stringing from rifles so shot is common when the rifle's not pulled back into the shoulder the same way for each shot. There's also a shift in windage zero from sitting at a bench to standing up on your hind ligs; shots to to the right more so when at the bench.
If the rifle's trigger has a really heavy pull, the impact of the trigger finger transferred to the rifle when the sear's released and the finger lever comes to a hard stop is quite a force. If that force is not in line with the bore axis, it'll pull/push the rifle to one side. Good way to see this is dry firing and watch were the scope's reticule moves when the firing pin snaps home. If it jumps left for a right handed shooter, the trigger finger's not far enough onto the finger lever; it pulls back at an angle from right to left. If the trigger finger's too far in, it pulls the rifle to the right moving the recitule that way when the firing pin snaps.
One sure way to have horizontal shot stringing is finger flicking when the round fires. That's when the trigger finger's unconciously told to jump off the trigger's finger lever when the sear releases. You gotta keep that finger on the trigger with it at the stops until the rifle stops moving from recoil. Practice doing this so it's second nature. Finger flickers never shoot very accurate. This is called follow through.
Alan
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Nice shooting. I've never got the patience to record my groupings properly.
Thank you. I find an advantage of keeping the targets (especially including the bad ones!) means I can look back and see an average trend of the POI. With my 130gr TTSX hunting load I have now got some 30 odd five shot groups which vary between 1.37" and 0.45" and average 0.846" which are all around the 1" high POI. Another advantage of recording is confidence...I go to the range two or three times a month and I can see that the practice has improved my shooting constancy no end. I do the first shot cold barrel with my Hunting round and that is often surprisingly close to the 1" high mark. Each session I also do a group with the HPS target master to use as a control...they shoot to a slightly lower POI, around 1/2" high and usually into below an inch...and then whatever load development rounds I am working on.
The star at the moment is 110gr TTSX which are working out even better than the 110gr V-MAX, both of which have ended up using the same powder charge. But keeping records means I am not complacent! The 110gr TTSX produced an amazing (personal best) 0.308" 5 shot group on 10. October, the same session saw the V-MAX manage an 0.819" a 0.66" but also a horrible 2.187" AARGH! Nonetheless group centre / nominal POI was still just over a quarter of an inch from 1.5" high for all three V-MAX groups.
I had come to the conclusion after reading the rifleman.org.uk/Fuller_group_diagnosis.htm that I am possibly good for around 0.5" and the rifle and ammunition are probably good for the same. Which means that although most will fall into groups below an inch, when our extremes coincide it is 1" left, right, up or down from nominal POI and that means a potential 2" group...neatly illustrated/confirmed by my 10. October session!
Alan
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vertical or horizontal stringing is usually a clear indication of a variable from the position or shooter technique
This is one of mine
Fox 130gr .270 factory ammo
shot from the end of a park bench turned on end to create a standing shooting table
I felt the lateral movement in the shots
This is one of mine
Fox 130gr .270 factory ammo
shot from the end of a park bench turned on end to create a standing shooting table
I felt the lateral movement in the shots
That is clearly illustrated in Dodgyknees post...the shift in POI between his and his wife's hold on the rifle...either that or it is effectively an 1.5" 6 shot group.
I can't help think there are too many variables to be able to identify any simple cause...dodgyknees will have a lot of groups with identical pattern and POI shift to be able to identify the barrel warm up as the perpetrator in a 0.618" 3 shot group, but my marksmanship, rifle and ammunition aren't up to it by any means.
Alan
Do you get the issue with all types of powder?
Some powders are position sensitive. Try lifting the muzzle up before firing so the powder falls to the rear of the case (where able to safely do so!).
wildfowler1
Well-Known Member
Christ my youngest HWV does that, now you have made me think. The pointer bit I mean . Mind they tell you anything up north. Wf1
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