If ranging in yards, you take the size of the target in inches multiplied by 27.8 then divided by your mils= distance. at what power setting is this the formula for? And if you go from lets say 5x to 10x where does that factor into the equation?

SR,

The information on your scope should tell you what power to range. Some scopes are set to range at max power, others have a specific power for ranging. This is one of the advantages to a FFP scope, which ranges at any setting.

I think someone did a table on what the factors were for ranging at different powers, but I don't remember when.

Mark

What scope? FFP or SFP. If FFP then it doesn't matter as it will range correctly on any power although at lower powers it will be harder to break down the mils as the reticle will be smaller.

If SFP then it depends on the scope. But you can check on what power you range correctly on by putting a yardstick, 36", at 100 yards and when 10 mils, usually the space from one heavy duplex of the reticle to the other, fits that 36" then that is the proper scope power to range. I'd suggest against trying to figure formulas for ranging on different powers as it will probably be more confusing than helpful and sometimes scope power rings aren't 100% correct.

It's the IOR 2.5-10x42 FFP, I think it was shipped out today so I should be getting it later in the week.

FFP then it will range at any power so you're all set but as I mentioned it will be harder at the lower powers. You'ld probably be ebtter off ranging at 8-10x.

That's simply not true, and it amazes me that so many people still think it is. If your scope is set up to range at 10x, as most SFP variables are, then you simply divide your mils by the power divided by 10. So if you range at 18x, take 2 seconds and divide your mils by 1.8. This isn't some sort of approximation, it's exact. Also, you're not any more likely to be bang on 10x when ranging (unless there is a click stop for it) than you are for any other marked power setting on the scope. Ranging at 18x (or whatever your max power is) has the benefit of the target covering more of the reticle, which makes your mil reading inherently more accurate. If your scope ranges at some other power than 10x, simply make a table where you take all the marked powers on your scope power ring, divide them by the ranging power, and *bang* that's your correction factor.

Vern and I have been doing this with the FleaScope ranging at 18x, and I for one would never go back. If you have a FFP scope, it's not an issue, as pointed out above.

This question seems to come up about once a month.

Cheers,
--Hawk

The 3-18 isn't FFP?

Nope

Reb that's all well and fine if your scope is properly calibrated which alot aren't. Hell if it ranged on 20x then you could just put it on 10x and cut it in half right? But who says the 10x mark is exactly 1/2 of 20x? If you wanted to do this with a SPF scope then I would suggest you spend a day at the range with a yard stick and figure where all the powers are and mark the power ring well enough so it doesn't rub off. I've changed over to all FFP so I wouldn't have to worry about it.

Also for people like you and Vern it wouldn't be a problem as it wouldn't confuse you anymore but when we have a guy asking what power his scope ranges on I think he needs to figure out a few more of the fundimentals before confusing himself with any other math. Schmidt that's not a slam on you. Just trying to explain my statement. I guess it would have been more correct to say:

"I'd suggest against trying to figure formulas for ranging on different powers as it will probably be more confusing for a newer shooter than helpful and sometimes scope power rings aren't 100% correct."

I stand by that statement.

No problem Rob, I'm just trying to get more familiar with how the scope works before I actually get it. Up till now I know how to range with a Dragunov reticle and that's about it.

I just got my 2.5-10X42 FFP IOR, they are right, at 2.5 its a little hard to range.. lol

1Eye

Rob,
I agree with your statement 100% my friend. Here at school I have made a barber pole for checking the variable scopes now. I then scribe a mark at the students request on the power ring. I can pretty much feel out a shooter and know if he can handle the extra numbers.

Like anything else I feel a new shooter should stay with what he or she knows until they are totally proficient before ever moving forward.

flea