Before I attempt another explanation, let me throw out 2 disclaimers. #1. I am not a teacher and therefore do not have the giftings of bringing to light the mysteries of shooting. #2. I am endowed with very limited communication skills. With these 2 disclaimers I will cinch up my belt and attempt another round of explanations.
From what Songdogger told us, he shot out to 500 yards to verify point of aim versus point of impact. That being said, it is not his shooting ability off of lead sleds, bipods, etc. You won't miss a 24" target at 450 yards when you have already been practicing shooting at 500 yards.
The observed problem is that Songdogger shot 8 times and all of them were high. The only thing in the thread that I did not see was what his aiming point was in relation to where the bullets were impacting.
In the old days, rangefinders ranged a target and returned your data in a line of sight format. From this reading, it was entered into a ballistic program along with the incline ange to arrive at a shooting solution.
With Songdoggers balistic program already in use through his binoculars, his shooting solution already compensated for the incline angle, wind, barometric pressure and all the other things that go into a solution for a first round hit.
With fear and trepidation, let me enter into a realm that is difficult to understand and more difficult to explain. For you mathmaticians out there, please bear with me. If I were to draw a triangle on a piece of paper and at the top of the apex I drew a horizontal line that was parallel with the base of the triangle and then measured the distance between the 2 horizontal lines with a piece of string it is going to be shorter than the slope of the triangle. If I were looking through ballistically corrected binoculars, the shooting solution of 450 yards is shorter than the actual distance to the apex. This is important only from the stand point that the bullet is actually traveling further than the 450 yards shown in the shooting solution, but it also means that the environment has a longer affect on the bullet than what one might expect.
On flat ground, a head wind generally means that the wind is traveling parallel with the ground. In the case of shooting down hill, we are not dealing with a headwind in the sense that it is moving in a horizontal position. In this particular scenario, the wind is traveling upslope generating a lifting affect.
Because of the unique form of a bullet, when it is fired from a rifle, the projectile travels in a parabolic curve. Ugh...this is difficult. The rifle is shot from 13" above ground level with the full force of 10 mph wind on the underside of the bullet, generating an unknown lift. This was proven by missing 7 of the eight shots that were too high to impact a 24" target. I suspect that the shot that actually connected with the target was shot with the crosshairs of the scope below the belly line of the animal trying to compensate for the lifting force of the wind on the bullet while in flight.
So, how do you factor in a wind force that is lifting your bullet upwards as it speeds to the target? I don't have any ballistic program that will give me a solution. So I have devised a method, although it is not anywhere perfect, to try to compensate for the uplift on a bullet that is shot downhill with with an unknown uplifting force.
This seems to work, but the logic is full of holes. My ballistic program is designed to compensate for horizontal drifting because of wind. Because of the bullet trajectory while traveling down hill I have settled on using a full value wind deflection and deduct that from my shooting solution in MOA increments. In the case of Songdoggers experience, his ballistic program indicates 4.5 MOA for 450 yards.
I'm fairly new to long range shooting, learning most of what I know from internet research, including this forum. I'll expose myself to criticism in his thread, rightfully so, but I'm good with that if it helps me learn.
I have a Fierce Edge 300 Win Mag with a Swarovski Z5 3.5-18 x 44 shooting Berger 210 VLD target bullets sighted in with a 200 yard zero. I programmed my Leica Geovid HD-B rangefinding binocs using their ballistic calculator with inputs specific to this setup. Using the Geovid's feedback in MOA clicks, which self-adjusts for environmental factors (temp, pressure/elev, angle), I then shot the gun at 50 yard intervals out to 700 yards. It had ½ MOA accuracy out to 400 yards. Beyond that, the bullet dropped more than expected. I then lowered muzzle velocity in the ballistic calculator until the drop charts matched what occurred in the field, to within 1" out to 600 yards – that's all I needed since the scope's elevation turret stops at 53 clicks. I then reprogrammed the Geovid.
Last week, I ranged a bull elk at 413 yards with a headwind of 10 mph. Adjusting for a 4000' elevation difference and environmental conditions, the Geovid correctly called for 5.1 MOA of elevation. The shot missed high, maybe a foot over the back. The bull moved to 450 yards, the Geovid called for 6.2 MOA, but I purposely kept it at 5.1 MOA. Still, the shot missed high – twice. Still at 450 yards, I dialed it down to 4.0 MOA, and the 4th shot hit a few inches below the back and spined him. I shot 4 more times to finish him off, each appearing to hit high as he expired on his own. Nice bull down, but I just sat there in disgust. I've had several kills already at the same distance with a factory gun using simple holdover values.
8 shots, all high, each at a still, broadside, and very accommodating bull. I felt relaxed with steady crosshairs, verbally reminding myself to gently squeeze the trigger. I verified the 200 yard zero immediately before and after the kill - surprise, it's not the gun.
Here's a breakdown of likely factors, and where I need the feedback:
1 – I forgot to adjust parallax. The knob was set to 100 yards. After the sighs, cries, and rolling of eyes – could this cause shots to consistently hit 2 foot high at 400-450 yards?
2 – I shot at the bull prone from a bipod. The gun was sighted in and practiced long range on a bench with a Lead Sled (I've since read "no-nos" about that). During pre-hunt practice, I did verify point-of-impact with a bi-pod, but only a few shots at 100 yards, and from the bench, not prone.
3 – The bullets may have travelled through the tops of thin grass tufts about 30 yards from the muzzle. With the naked eye, it looked like the shots could clear it. But, through the scope, I occasionally noticed the scope slightly blurred at the bottom, likely from the grass bending and straightening in the head wind.
Advice, opinions? Bring it.
