Problem: accurate at long range - inaccurate at short range

MSR

Member
AIUK Saviour
I've discovered a curious problem. At ranges of 40m and 50m my groups are correct for elevation, with some dispersal left and right (but that was me not aiming well). The important result was that they were all correct for elevation and at least three or four were in the gold.

The problems started when I dropped to 20m for a warm-up and tuning session. I noticed that all my groups were 11 o'clock blue. Consistently. Sight was dead centre on the gold, and the groups went high and left. I moved back to 50m and was peppering the gold again, with the arrows distributed evenly across the horizontal and none of them high and to the left. I moved back to 20m and instantly they were high and left.

Back at 20m I adjusted the sight to compensate and nothing changed. I ended up with the sight set to zero (unable to adjust further) and still, nothing changed at 20m. At 40m and 50m I was fine. At 20m I was high and to the left no matter what I did.

I consulted two club coaches. They spent some time orbiting me as I shot and pronounced my technique text book. One used the word 'perfect'. Under other circumstances I would be happy about that. However, this just means that instead of looking at myself, I have to look at the equipment, I there is no obvious problem with the equipment!

I adjusted the button by moving it inwards, just in case the centre shot tuning was incorrect. No change.

With the button adjusted I experimented further at 20m by aiming at 6 o'clock blue. The group moved down, but stayed in the same place (high and left) relative to my aim point.

I then shot three arrows with the aim point back in the gold, followed by a bare shaft. I then moved the aim point down into the blue and shot three more. The results are below:

20m groups (612 x 816).jpg

You can see the two groups, and the bare shaft.

SF 70", 36lb limbs, 40lb OTF
30" ACE 500 spine

So, at 40m and 50m I'm fine. No problems. At 20m I'm always high and left. No one can see anything I'm doing wrong in my form. Adjusting the button made no difference at all.

Wild Theory:

It has been suggested by a non-archer friend that the arrows are not able to stabilise themselves in time over the short 20m distance. The analogy given was that of artillery shells in flight. Some examples were initially unstable at their muzzle velocities, only calming down later in their flight as velocity dropped. It was suggested that my arrows could be performing the same way. Just a thought. In fact, it's the only thought I've got! In the absence of a form problem, and the absence of any obvious equipment or tuning problem, I don't know where to begin.

This is my outdoors config. My indoors string has a different nocking point and I use alu shafts. I haven't tested that config, however, as I haven't yet shot indoors with this bow.
 

geoffretired

Supporter
Supporter
One question I have, is how did you come by the sight mark for 20m? Did you, for example, shoot those arrows at 20m to get sight marks at some point in the past? Did those same arrows hit golds at 20m last time you shot them?
With the sight adjusted to zero..... does that mean it was at the top of the scale bar and would not go higher? If the sight is at the top of the scale bar, it might be possible to raise the sight further by moving the scale bar into the higher setting( unless it is already up there). The other limit to raising the sight, is where the top curve of the sight window is compared to the gold when on aim. Some archers find the upper edge of the sight window obscures the gold and their arrows are still shooting high. Lowering the bow simply makes that worse.
One thing about results at different ranges is that the group size is expected to double more or less with double the distance. If the short range groups a re relatively bigger than that, we usually look for clearance problems or launch problems.
Shooting through paper at 3m is good for some problems like this. You will expect a tear to one side or the other but a vertical tear would be a sign of some unusual launch. lipstick on the rest and button might show some contacts, and on the sight window and arrow shelf. Powder will do just as well. Rub marks on the feltchings might be showing they are catching somewhere.
You are shooting thinner arrows, I suspect, than the allys. How are they placed against the button? Has the rest been lifted compared to its position for fatter arrows?
 

Mistake

New member
Ironman
First thing i'd check is are my arrows straight

Then I would go through a check list pretty similar to Geoff (although I wouldn't bother with the bow window as it's a riser I've used for 4 years now.)

Then if I could I would also try different arrows. My x10s are stiffer than my AGCs on paper, but out of the bow my x10s are as perfect as I can get them, and my AGCs shoot stiff and looser groups
 

Mark31121

Member
Ironman
I'd look for clearance issues, they have a bigger impact at 20m than at 50+ and I'd put a smaller target on to give you more of an idea of grouping - I was using a single 40cm spot to check my bow setup on Friday at 20 yards (new arrows) before moving to 30m to a full bare shaft check.

My old arrows looked fine at 20 yards, bare shaft within inches of the fletched - out to 30 yards and the fletched were all in the gold with the bare shaft off the target. I then went home and ordered new arrows.

apologies for swapping between yards and metres, it all depended on what the targets were set out on the day
 

KidCurry

Well-known member
AIUK Saviour
Well first the high impact... move your sight up a few clicks. All yo have here are a slight left impact not a high left impact. This might mean raising the evevation scale bar to get the sight pin higher.

500 spine for 40# and 30" arrows I think would be a bit on the stiff side. Have you tried a softer spine, say 570? This could even be exacerbated by a slightly shorter draw at 20m. Do you use a clicker? I have seen, many times, when people are shooting longer distances they instinctively draw a bit longer.
 

mbaker74

Supporter
Supporter
AIUK Saviour
The height issue is purely a sight problem, you need to move it further up.
Your bare shaft at 20 metres says your arrows are way too stiff... Also your nocking point is a bit high.
 

MSR

Member
AIUK Saviour
Thanks, folks. From your replies I have complied the following to-do list:

1. Check arrows are straight and review bow window
2. Check rest height and button are correctly tuned to the alu shafts
3. Check nocking point
4. Move scale bar up
5. Check clicker is set correctly
6. Agonise over whether my arrows are too stiff (I suppose the easiest and most reliable test of that is to order a couple of softer spines and compare the results on the target).
 
Just to add something else to what has been said. You should set the button to just over centre, when this is done correctly don't alter it it to achieve any movement as you have done. It is either correct or not. I think it is likely your arrows are stiff as has been said. When an arrow is over stiff apart from the issues of clearance you can get a point blank effect. This means that regardless of how much you alter the sight at short range the arrow impacts in the same place. This is similar to what your friend suggested. I would also suggest you do the walk back test as an arrow can be apparently tuned at certain ranges but out at others.The walk back will show the pattern to indicate the necessary changes, the button pressure and in or out. I have rarely had to alter the latter if set just over the centre of the arrow at the start of the process.Hope this may help.
 

Steve Ruis

Supporter
Supporter
Nobody has Mentioned Spine Mismatch Yet

The high 20 yard mark may be just a poor site mark but the left-right problem may be to poorly spined arrows. Poorly spined arrows launch from the bow at an angle to the target line and will be off line farther and farther the longer the arrow travels. If you have adjusted your sight aperture's position for 40-50 yards, it will be off at 20. A correctly tuned bow will have its sight aperture in the same plane as the bowstring (and riser central plane) and the arrows will fly down the middle at all distances.
 

MSR

Member
AIUK Saviour
A correctly tuned bow will have its sight aperture in the same plane as the bowstring (and riser central plane) and the arrows will fly down the middle at all distances.
Hi Steve, can you clarify this? Are you saying the sight aperture should be in the same vertical plane as the string when tuned?
 

Steve Ruis

Supporter
Supporter
Yep, it is one of the first things I check with a new recurve student (May I look at your bow?) I visually line up the string with the center of the riser and hope to see the aperture bisected by the string. If the aperture is out to the left, the arrows are generally too stiff and to the right, too weak (of course reversed for our left-handed friends).

A basic criterion for accuracy is the arrow needs to be in the same vertical plane as is the target center (the arrow is a simple projectile and can't curve ... absent wind). In order for the bow to push the arrow to target center it has too have its string plane in that same plane too.
 

Steve Ruis

Supporter
Supporter
If you want to check your tune, just place your sight's aperture in the string plane as described before and shoot some arrows. If they hit the target to the left of your aiming spot, they are too stiff. If to the right they are too weak. If you have draw weight adjustment left, you might be able to bring your arrows in by adjusting the draw weight, otherwise you need to tinker with your arrows. A bare shaft test would tell you the same, but it is more complicated.
 

mbaker74

Supporter
Supporter
AIUK Saviour
I have to disagree with this, the impact of the fletched arrows on the target is dependant on the button stiffness.
Have you done a full set up on your bow? i.e.

Center the string to the limbs
Align the tip of the arrow to the left of the string,
align the sight pin directly above the centre of the arrow, then don't touch it.
Make sure the sight pin stays above the centre of the arrow as you slide it up and down. A surprising number of bows are not aligned between the sight rail and the riser.
Shoot arrows at a close target, and adjust the button pressure until they are central.

Move out to 20 yds and shoot groups with fletched arrows and check button position is giving your centralised groups.

Then shoot unfletched arrows and fletched together. the position of the unfletched tells you the arrow behaviour. If they are below the fletched group, your nocking point is too high and vice versa. Set the nock point first so all arrows land in the same horizontal plane.

Once they are level, if your unfletched arrows are left of the fletched, they are too stiff, right, too soft. You can then look at increasing or decreasing poundage, point weights etc to bring the groups together.

Once you have them all grouping, move back to 30 yds and do it again.

If the unfletched are more than 6-8" away from the fletched group at 20 yds, you are probably a whole spine out on your arrow selection.
 

MSR

Member
AIUK Saviour
Thanks for the advice.

Haven't had much time for archery, lately, so have yet to sort this out, properly with testing. I've just had an evening tuning, checking and aligning session (what else to do on a Saturday night?) and have sorted out limb weight, alignment, centre shot, button pressure, nocking point (discovered that it was at least half a diameter too high!) and tillering: in the end I've left the tiller at zero for both limbs. I want to do a lot more shooting and bare shaft testing before I mess about with tiller. It comes last on the list.

Tomorrow I will test at 20 yards again. Or metres. Depends who lays out the range! Anyone over 60 and it's always in yards ;-)

I have an ambition to hire an expert coach one day (probably just for the one day, as well) and work with this person to get my gear tuned and/or define a list of replacement gear (such as correctly spined arrows). That's for another day, but I'd be interested to know if anyone has done this and what the experience was like... and perhaps more importantly, where they found their expert! Other than archery shops, I'm not sure where to look. Never seen any such service advertised.

P.S. have just discovered electrician's tape makes an excellent nocking point! I cut the diameter down by half and wrapped it on. Far superior to other tapes I've tried, and far preferable to spending two hours swearing over thin thread while I try to tie the kind of knots key hole surgeons take years to master.
 
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