Home Forums Hunting & Shooting Hunting Optics How to use that new SWFA scope- reticle, turrets and proper usage.

This is good stuff - thanks for taking the time.

As much as I'd maybe like to, I can't get MIL going and I'm stuck on MOA.

One thing to consider. Some of the new rangefinders and rangefinder binos, with ballistic software in them automatically take many of these atmospheric conditions into account.Along with angle change ect. I have found the information that my leica HD b s gives me in mils has been spot on from below zero to hot summer temperatures. I still have a range card, but don't use it. I dial what my binos tell me. I have only shot to 800 with it,generally concentrating on shots from 500 to 600 for 1 shot kills on coyotes.

Me too....and one of the primary reasons is I'd have too much crap to switch over.

Are you guys still thinking in terms of inches of correction to make?

Yep

I'm that same way with lat/lon vs UTM but have no problem going back and forth between moa and mils, go figure.

Everything described in this thread applies to MOA as well as MRAD.

I totally rock mils as being 3.6 inches at 100 somethings. Kidding, sort of. I'll take that factor of ten stuff anytime anyhow though. UTMs too.

Thanks to Jordan and the others who are answering questions.







1). Screw up on my part. Corrected MV is 2,840fps.


2). One number to input versus multiple. Batter way to go.









The ballistic function is good, however in truly steep conditions at long range unless it's showing both straight line and corrected distance your wind corrections will be wrong. Just something for people to keep in mind.

This is generally what happens within a day or two when die hard MOA users learn to use both MOA and mils correctly-


"Wow both are just numbers that I spin to and they both work the same"

and then

"Wow, you know mils is easier to see and count on the reticle"

and then

"Wow, the drop corrections are easier to remember in mils"

and then

"Wow, wind brackets are easier with mils"


And then....



"I'm selling all my MOA scopes".





Seen't it. DOZENS of times.

Wind holds in the high country suck. It may change twice especially being above the deer shooting down into a basin. Solution: for me get closer. I have found with my geovids on very steep downward angles that there is .1 mils less per 100 yds hold, than a shot with little to no elevation. That is a rough calculation, but pretty consistent.

*

That's pretty much it. I've seen it a bunch of times, myself, after going through that very process myself several years ago. Though I ran both MRAD and MOA for a while while I transitioned the majority of my herd over to MRAD.

I would add this, though- "Wow, you know mils is easier to see and count on the reticle, and the turret".

I don't see how it simplifies anything. If you know the current barometric pressure at sea level, plus your temperature and altitude, you can calculate your station pressure. That's important because it tells you that station pressure accounts for both temperature and altitude. That means the only additional thing your ballistic solver needs besides station pressure is RH*. If you use corrected pressure instead, then you also need temperature and altitude in order to calculate your station pressure.

D-A basically gives you station pressure + RH, and then 'corrects' or relates it to some altitude where you _would_ be if everything was at the mythical ICAO 'standard' pressure. That's fine, but it actually _adds_ a level of complexity and abstraction to things, as far as I can see.

*Actually, I'm not convinced RH is a factor if you're using station pressure, but I'd have to review a bunch of stuff to feel confident of that.

So, what am I missing?

Okay, thank you. I'm less confused now. (-:

be interesting to see at what velocity/BC/distance that temp RH and air pressure make a 1 inch difference in POI.

I really don't know.

I expect to hunt between 4500 and 9500 feet ASL

temp between 0 and 90 F (30-60 F most often)

BC - .350 probably (is that officially a ping pong ball?)

distance 100-250 yards.

ps appreciate the original post. useful, easy to understand, helpful same as how to mount bases, scopes, rings (degrease, degrease, degrease)

You're right about the calculations, though RH does affect a ballistic solution, because it changes the effective density of the air, regardless of air pressure. Water vapour molecules are actually lighter and less dense than air molecules, so high RH decreases the air density. The effect of RH on air density is minimal, though, compared to pressure and temperature.

The way DA simplifies things, is that there are devices that use sensors to take the measurements and spit out a DA number for you to enter into your ballistic app. That way you don't have to manually take 4 measurements and enter each in separately. If your ballistic app is equipped with on-board sensors to take all necessary measurements, then it doesn't matter which air density calculation standard you use, except that you need to remember that the fewer measurements you can take, the better, as each measurement introduces error into the calculation. So measuring absolute/station pressure directly is better than taking a barometric pressure measurement and then calculating the station pressure using a temperature and altitude measurement.

They are, and if you got drop charts in your hand they are just the same. It's just simpler for me dealing in 'inches'

Does a critter hit with MIL adjustments die quicker than one hit with MOA adjustments? Thanks

At 250 yards it's pretty negligible.

Assuming 2900 fps MV, at 250 m your bullet will drop the following amounts from a 100 m zero:

4500 ft ASL, 0F
9.1"/0.9 mil

9500 ft, 90F
8.4"/0.8 mil

Not even a 1" difference. At further distances the differences become very large.