benEzra
Moderator Emeritus
I posted the following on an AK forum, but I know there are a lot of AK aficionados here as well, so...
I run a Kobra EKP-8-02 (slimline button-cell version of the Kobra) on my SAR-1.
After about a year and a half of messing with it, shooting it, and even a little USPSA carbine with it, here are some thoughts and observations:
One of the first things you notice about the Kobra is that it is a very tall sight (3.8" from the bore axis to the center of the lens for the EKP-8-02; I assume it is probably the same for the AA models, but have never measured one).
While a tall optic is usually viewed as a disadvantage (and it it prevents you from being able to cowitness the irons), it actually does have some advantages with regard to shooting at moderate distances. According to my ballistics program, with your typical 122/123 grain FMJ and JHP, if you zero the dot at 50 yards, you are only 2" high at 100 yards, close to dead-on at 200 (0.6" high), and only 14.4" low at 300 yards, which is about my limit with an unmagnified optic and 7.62x39mm anyway. The tall sight height keeps the bullet closer to the line of sight between 20 and 200 yards.
The downside of a tall sight height, though, is that at close range, the bullet starts out LOW. At the muzzle, the bullet is 3.8" below the dot, and angles up until it crosses the dot at 50 yards (assuming a 50-yard zero). BUT, the Kobra's other reticles give you lower aiming points that allow you to compensate some. The top of the chevron is right on around 20-25 yards, IIRC, but my favorite reticle for close-range shooting (like typical USPSA stages) is the T-bar:
At around 7 yards or so, the bullet trajectory crosses the bottom of the central bar, so anywhere between about 7 and 50 yards, the bullet will hit between the bottom of the central bar and the top of the reticle (even with the top of the "T"). Between about 7 and ~20 yards, the bullet will land between the bottom and the top of the central bar. So at close range, if you place the central bar of the T-bar over the target, you WILL hit it; at such close range, it's a pretty precise aiming point.
You can experiment with the dot-chevron reticle in similar fashion:
The bullet reaches the bottom of the chevron between 10 and 15 yards if the dot is zeroed at 50 yards, so for unknown-distance shooting that might involve some longer shots, I prefer the dot-chevron since the T-bar lacks a precise aiming point for longer shots.
Another thing, not all that practical but interesting nonetheless. If you need to shoot from very low prone, or beneath low cover such as a vehicle, Sonny Puzikas and others have suggested turning the rifle sideways with the ejection port up and using the charging handle as a crude sight, to get the gun closer to the ground than the magazine will allow. Well, with an optic, you can just use the optic, if you can get an eye low enough. Just on a whim, I ran the numbers for bullet drop for a rifle turned sideways (sight height zero, no correction for drop) using the optic, and the bullet doesn't even drop an inch until 40 yards, and is only ~3 inches low at 100 yards. Left/right error is more pronounced; with the rifle turned sideways, the bullet starts out 3.8 inches left of the dot and drifts to the right, until it crosses the line of sight at an unknown distance (probably around 25-30 yards, but you'd have to verify at the range) and keeps moving to the right with increasing distance. With the rifle flat, left-right error will throw you off before bullet drop will, but a back-of-the-envelope guesstimate says that you'll still hit within 50-100 yards. Not sure if there's much real-world application for most of us, but it's interesting anyway. And I'll bet that if you used the T-bar reticle, aiming with the bottom of the central bar would greatly reduce lateral error. I may try it next time I get to the range, just out of curiosity (assuming the range is deserted enough that I can do so without getting any "Why are you shooting your rifle sideways like a doofus?" comments).
I run a Kobra EKP-8-02 (slimline button-cell version of the Kobra) on my SAR-1.
After about a year and a half of messing with it, shooting it, and even a little USPSA carbine with it, here are some thoughts and observations:
One of the first things you notice about the Kobra is that it is a very tall sight (3.8" from the bore axis to the center of the lens for the EKP-8-02; I assume it is probably the same for the AA models, but have never measured one).
While a tall optic is usually viewed as a disadvantage (and it it prevents you from being able to cowitness the irons), it actually does have some advantages with regard to shooting at moderate distances. According to my ballistics program, with your typical 122/123 grain FMJ and JHP, if you zero the dot at 50 yards, you are only 2" high at 100 yards, close to dead-on at 200 (0.6" high), and only 14.4" low at 300 yards, which is about my limit with an unmagnified optic and 7.62x39mm anyway. The tall sight height keeps the bullet closer to the line of sight between 20 and 200 yards.
The downside of a tall sight height, though, is that at close range, the bullet starts out LOW. At the muzzle, the bullet is 3.8" below the dot, and angles up until it crosses the dot at 50 yards (assuming a 50-yard zero). BUT, the Kobra's other reticles give you lower aiming points that allow you to compensate some. The top of the chevron is right on around 20-25 yards, IIRC, but my favorite reticle for close-range shooting (like typical USPSA stages) is the T-bar:
At around 7 yards or so, the bullet trajectory crosses the bottom of the central bar, so anywhere between about 7 and 50 yards, the bullet will hit between the bottom of the central bar and the top of the reticle (even with the top of the "T"). Between about 7 and ~20 yards, the bullet will land between the bottom and the top of the central bar. So at close range, if you place the central bar of the T-bar over the target, you WILL hit it; at such close range, it's a pretty precise aiming point.
You can experiment with the dot-chevron reticle in similar fashion:
The bullet reaches the bottom of the chevron between 10 and 15 yards if the dot is zeroed at 50 yards, so for unknown-distance shooting that might involve some longer shots, I prefer the dot-chevron since the T-bar lacks a precise aiming point for longer shots.
Another thing, not all that practical but interesting nonetheless. If you need to shoot from very low prone, or beneath low cover such as a vehicle, Sonny Puzikas and others have suggested turning the rifle sideways with the ejection port up and using the charging handle as a crude sight, to get the gun closer to the ground than the magazine will allow. Well, with an optic, you can just use the optic, if you can get an eye low enough. Just on a whim, I ran the numbers for bullet drop for a rifle turned sideways (sight height zero, no correction for drop) using the optic, and the bullet doesn't even drop an inch until 40 yards, and is only ~3 inches low at 100 yards. Left/right error is more pronounced; with the rifle turned sideways, the bullet starts out 3.8 inches left of the dot and drifts to the right, until it crosses the line of sight at an unknown distance (probably around 25-30 yards, but you'd have to verify at the range) and keeps moving to the right with increasing distance. With the rifle flat, left-right error will throw you off before bullet drop will, but a back-of-the-envelope guesstimate says that you'll still hit within 50-100 yards. Not sure if there's much real-world application for most of us, but it's interesting anyway. And I'll bet that if you used the T-bar reticle, aiming with the bottom of the central bar would greatly reduce lateral error. I may try it next time I get to the range, just out of curiosity (assuming the range is deserted enough that I can do so without getting any "Why are you shooting your rifle sideways like a doofus?" comments).
