Rob, got you covered.
I should probably go back to the PO 3,5x21 thread and edit my own data, because ITS WRONG.
it took me a little while to figure out, what exactly was the case that I was having with my Kashtan as well- at distances between 200 and 400 meters.
So...just like you, i had a little trouble CONSISTENTLY hitting the man size silhouette. My POA was consistent, just as i thought- center of mass. But what does that mean exactly? Think about this. do you have a REPEATABLE POA? you dont have a 9x sniper scope, but a 2x, so even if you are a little bit off while engaging targets at 400-600 meters, you will miss.
my shots, just like yours, were hitting the man-size targets' head at distances between 200 and 300 meters, and about ten per cent going OVER the target.
So. whats going on>? We all have read the manuals, and understand that to properly zero your 1P78 AND PO 3,5x21 you have to be 22-24 centimeters high at 100 meters. Now lets look at the ballistics of the 53 Gr 7N6.
-maximum distance to the projectile's maximum height (or bullets peak of its trajectory) is just over 200 meters. The maximum height is roughly 40 centimeters, which is about 16 inches.
You see, using PO 3,5x21 you dont have to worry about your POA not being your POI, since it is equipped with a tripled hash-marked cross, indicating BDC for 200 and 300 meters, respectively....so instead of always using center of mass POA, i would cheat and just use the hash marks for the appropriate distances.
now lets get back to Kashtan, which does not have that reticle, so you have to use 400 meter zero. The rifles are AK-74 with roughly 16 inch barrels. Rifle is zeroed 22 cm high @ 100 meters. Using the center 400 meter chevron and now aiming at the center of mass of a humanoid silhouette target @ 200 meter where will your bullets strike?
This is where you, Rob and I were having issues. Why? Because the projectiles are still rising.
100 meters- 22 cm high
150 meters- 30 cm high
200 meters- 39 cm high!!!
thats the 7N6 peak of the rainbow, and its happening between 200 and 300 meters if the scope is zeroed according to the proper instructions. Thats right about 16 inches. Take a measuring tape, and place the bottom of it on your center of mass, your chest. The top is right at your nose.
so there you have it. so-much for so called "center of mass". Would any military jeopardize the fact that the probability of hitting your target goes down by nearly 60%? (your head is approximately 3 times narrower then your chest, and hence the bullets are hitting right at the HEAD area you have much higher chance of miss) Of course not. Its because your POINT OF AIM IS WRONG
Zen and I have been talking about this issue for a while. I have been doing extensive tests with my SVD and proper way to use the PSO-1 scope. Its almost the same issue. Place your target @ 500 meters, set your turret at "5" for 500 meters, use 1991 153 Gr. 7N1, aim for the head to make that sniper shot, only to realize that you will entirely miss the human target.
Point of aim is the key. Soviet doctrine has always been taught to aim for the BELT BUCKLE. Not only it is repeatable, but it is not SOMEWHERE in the middle of 14x18 object (your chest), its right above the crotch area, so you have much more definitive point of aim.
NOw, lets go back to the SVD at 500 meters, with the missed head shot, and place the first chevron on the belt bucle. Where will the bullet strike? Right around the upper chest. Why? because the scope was calibrated to do this.
Same with Kashtan.
@ 200 meters, bullet is still rising, so if you aim at the chest area your round will impact much higher, possibly missing the target. Now aim at the Belt Buckle. At that point the round will strike right in the upper chest, right below the neck. At 300 meters the round is still about 30 cm (12 inches) high, and will strike right around solar plex area. 400 meters you will be ripping his lower intestines.
anyways, hope this helps, took a little while to figure out, but in the end pretty straight forward. beer time