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dbarnes4
4th May 2010, 22:20
Hey there, can any of you rifle aficionados help me with a question? I'm intending on putting a mil dot scope on my Saiga 7.62x39, my question is this: Could I use the mil dots for bullet drop compensation at any zoom, or would I need to use one particular zoom level for using the mil dots for holdovers?

I've read that some scopes are only supposed to be used at one specific zoom for range estimation via size estimation with the mil dots. I was wondering if it was the same for bullet drop compensation.

Thanks

Hunter
4th May 2010, 23:55
It is my understanding that BDC is set up for a particular weigh/velocity bullet but range estimating Mil Dots are universal that compares to a shape (such as a mans torso falling into between 2 dots give you an idea of distance).

GDubya
5th May 2010, 00:31
In the last 5 years, more higher end (>$1000) scopes are available in "first focal plane" reticules, where the dots and/or stadia remain the same relative to distance and are really "Mils" at all variable magnifications: the dots & crosshairs get smaller to almost invisible at very low power and very large/thick at high power. Second focal plane optics are more common, less expensive and rangefinding is typically done at the highest power.

Now, you can certainly utilize formulas to calculate and range-find with SFP reticles, including working out hold over. But at this point I have to ask, what are you expecting from the 7.62x39 round relative to what you feel you need in a scope? I have a very accurate Krebs KTR08 built from a Saiga and it's a 4 MOA gun out to 300 yards with it's limitation being the typical 7.62x39 ballistics:

100 yards +3.5 inches
200 yards 0.0 to -3.0 inches
300 yards -13 to -15 inches
400 yards -40 to -50 inches
500 yards -80 to -100 inches

That's why AKs are typically zeroed at 28 yards and then hit +/- 3" out to 200 yards. It's just not a long range gun. Subsequently, I'm using a 4 MOA red dot optic...

I hope this helps.

dbarnes4
5th May 2010, 01:30
Thanks guys, that's the exact information that I needed. The only reasons I'm even considering going past 300 yards with this gun is that I just bought some of the new Hornady 7.62x39 V-MAX ammunition which is a little faster than standard Wolf ammunition. I was curious how much more flat the trajectory was with the Hornady. And I thought the mil dot reticle might be a decent option for shooting with a hold over.

So basically, what I can learn from this discussion is that with a SFP optic (the only kind I can afford right now) I should only attempt to use the mills to estimate holdover at the maximum zoom right?

GDubya
5th May 2010, 09:41
According to Hornady, (http://www.hornady.com/assets/files/ballistics/ballistics_charts.pdf), their 123-gr A-Max loading falls very closely into typical external ballistics. Where Hornady and Corbon(with DPX) may exceed is in their terminal ballistics, but at 10x the price...
Comparatively, the downrange elevation of 7.62x51(.308Win) is about half that of 7.62x39.

The manufacturer should tell you what power the scope is calibrated for to get proper Mil-dot reading, though it's not always the highest magnification available because of the narrow FOV at longer ranges, eg. a 6-18x may be calibrated at 12x. And, again, the ranging calculations aren't as difficult as they first seem.
I doubt you'll find BDC for 7.62x39 unless you get a Com-bloc POSP-type and then you still need to consider the stated elevation adjustment range vs actual max effective ballistic range. You can lob a 7.62x39 somewhere? ~2 miles downrange with a 45-deg holdover but that's not what you want...

dbarnes4
5th May 2010, 10:10
Thanks again, I'll check with whatever manufacturer I end up with then. I never wanted a true BDC reticle like the Nikon series, just a mil dot.