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:
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.
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:
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.